MYOLOGY OF THE LIMPKIN
TED T. ALLEN
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
I am sincerely and deeply grateful for the generous
help and skillful guidance of my chairman, Dr. Pierce Brod-
korb, and for the use of his reference materials and skeleton
I also thank the other members of my committee, Drs.
E. C. Bovee, E. S. Ford, J. N. Layne, and J. R. Redmond,
for their help and constructive suggestions.
Grateful acknowledgment is also due the Florida State
Game and Freshwater Fish Commission for the issuance of a
special permit for collection of a small number of limpkins.
Dr. O. L. Austin, Jr., Mr. Anthony Austin, and Mr. Earl May
contributed needed specimens. Dr. Glen E. Woolfenden and
Mr. Robert McFarlane contributed specimens and also, along
with Dr. Dale E. Birkenholz, gave various other forms of
valuable assistance. I am indeed grateful for their help.
One summer of work was completely financed by a Fellow-
ship for Teaching Assistants from the National Science
Foundation, and partial coverage for another summer was pro-
vided by a fellowship from the College of Arts and Sciences
of the University of Florida. The monetary assistance was
invaluable, since it greatly reduced the time required to
complete the dissertation.
TABLE OF CONTENTS
ACKNOWLEDGMENTS . . . . . . . . . .. ii
LIST OF ILLUSTPATIONS . . . . . . . . iv
INTRODUCTION ................ . .. 1
DESCRIPTIVE MYOLOGY . . . . . . . . . 4
Muscles of the Skull . . . . . . . 5
Muscles of the Hyoid . . . . . . .. 54
Muscles of the Orbit. . . . . . . a88
Muscles of the Wing . . . . . . .. .98
Muscles of the Tail . . . . . . . 197
Muscles of the Leg . . . . . . .. 217
DISCUSSION . . . . . . . . .. . . 308
CONCLUSIONS . . . . . . . . .. . . 323
SUMMARY. . . . . . . . . . . . 327
LITERATURE CITED ............... . 329
BIOGRAPHICAL SKETCH . . . . . . . ... .339
LIST OF ILLUSTRATIONS
1. Lateral and posterior views of the skull of the
limpkin, showing attachments of the muscles in
the occipital region . . . . . ... 333
2. Lateral views of the skulls of certain birds,
showing the position of the cranial attachment
(anterior origin) of M. Dermo-temporalis . . 334
3. Lateral view of the skull of the limpkin,
showing attachments of the muscles of the jaws
and of the orbit . . . . . . . .. 335
4. Ventral view of the skull of the limpkin, show-
ing attachments of muscles . . . . . 336
5. Medial view of the left eyeball of the limpkin,
showing the muscles of the eye and their attach-
ments . . . . . . . . ... . 337
6. Palmar and anconal views of the left humerus,
showing attachments of certain muscles of the
wing . . . . . . . . ... . . 338
The limpkin, Aramus guarauna (Linnaeus), is the sole
living member of the avian family Aramidae of the order
Gruiformes. It occurs in southeastern Georgia, Florida, the
Greater Antilles, and the Neotropical mainland from Mexico to
Argentina (American Ornithologists' Union, 1957). The spe-
cies is known from a pre-Columbian site in Venezuela (Wet-
more, 1935) and from four localities in the Upper Pleisto-
cene of Florida (Wetmore, 1931; Brodkorb, 1956; Woolfenden,
1959). Other members of the family occur in Tertiary depos-
its of the Great Plains, Aramus sp. from the Lower Pliocene
of Nebraska (Wetmore, 1928), Aramornis longurio Wetmore
(1926b)from the Middle Miocene of Nebraska, Gnotornis
aramiellus Wetmore (1942) from the Upper Oligocene of South
Dakota, and Badistornis aramus Wetmore (1940) from the Mid-
dle Oligocene of South Dakota.
The living limpkin is adapted to a rather unique diet.
This consists almost exclusively of large snails of the
genus Pomacea, formerly known as Ampullaria, with occasional
other gastropod and pelecypod mollusks (Wetmore, 1926a: Cot-
tam, 1936). The bird usually takes the snail to a regular
feeding station and with its long, specialized bill pecks
through the operculum, extracts, and swallows the soft body
of the mollusk.
The bird occurs primarily in grassy marshes and wooded
swamps (Bent, 1926; Wetmore, 1926a;Nicholson, 1928). Where
bushes or trees are available it perches and nests in them,
often at some height from the ground.
Both the feeding and perching habits of the limpkin are
thus quite distinctive and differ from the usual condition
of its ordinal allies, the rails and cranes. Adaptations to
a specialized way of life would be expected to obscure re-
semblances to its nearest relatives and may account for some
of the disagreement over the systematic position of the
The subordinal position of the limpkin has not been es-
tablished with certainty, although all workers have referred
it to one of two suborders, the Grues or the Ralli. Some of
the difficulties involved may be seen in a brief review of
the opinions of other workers on the systematic position of
the Aramidae. Audubon (1839) thought Aramus to be allied to
the rails on the basis of the viscera. Nitzsch (1867) found
that the pterylosis resembles that of Grus and Psophia and
no other bird; nevertheless, he placed it with the rails be-
cause of peculiarities of the feathers themselves. Garrod
(1876) considered Aramus as being closer to Grus, on the ba-
sis of several anatomical features, especially of the skull,
sternum, and some aspects of the thigh musculature. Shufeldt
(1894) placed it with the cranes but considered the species
a perfect link between cranes and typical rails. Clay (1950)
found the aramid Mallophaga to be rail-like and strongly
different from the type found in cranes. On the basis of
the electrophoretic profiles of egg-white proteins, Sibley
(1960) thought Aramus to be closer to the rails, and he men-
tioned the large hallux, feathered head, and color of the
downy young as also being rail-like.
From a broader view, these opinions indicate that the
Aramidae are definitely related to both the Gruidae and the
Rallidae. A major purpose of this paper is to investigate
affinities of the three families through study of their com-
parative myology. Fisher (1955) remarked that detailed ana-
tomical work should solve the question of affinities.
During the course of this study, six limpkins were
available for dissection. Two were dissected in detail and
critical points were checked in the others. To represent
both wading and swimming types of Rallidae, two specimens of
the clapper rail, Rallus longirostris Boddaert, and two of
the coot, Fulica americana Gmelin, were dissected. Some
features were also examined on a specimen of the purple gal-
linule, Porphyrula martinica (Linnaeus). A specimen of the
crowned crane, Balearica pavonina (Linnaeus), was dissected
as representing a generalized gruid, and comparisons were
made with Fisher and Goodman's (1955) description of the more
specialized whooping crane, Grus americana (Linnaeus), and
Berger's (1956a)study of the appendicular myology of the
sandhill crane, Grus canadensis (Linnaeus). All dissections
follow the basic plan of the excellent work by Fisher and
Goodman (1955), whose descriptions are quite adequate as a
guide to dissection of the species used in this study. With
very few exceptions, each muscle discussed by those authors
is found in each of the other species, and only a few are
present that are not discussed by them.
In the descriptions of individual muscles comparisons
are made on the basis of their proportions, as if all spe-
cies studied were of the same size. Attention is called to
differences in general configuration, points of attachment,
and function, at the specific, generic, or family levels, in
an effort to determine the relationship of the limpkin to
the cranes and rails.
Muscles of the Skull
1. M. dermo-temporalis
Elongate and sheet-like dermo-osseous muscle. Covers
lateral surface of full length of neck. Attaches to cranium,
to furculum, to M. tracheohyoideus, and to skin of neck.
Lies just beneath skin and deep to lateral edge of
sheet of M. constrictor colli in anterior half of neck. Lat-
eral to dermal fasciculi of Mm. intertransversarii. Anterior
end superficial to posterodorsal portion of M. depressor
mandibulae, ventrolateral edge of cephalic part of M. cucul-
laris, anterodorsal portion of M. rectus capitis lateralis,
side of fourth and fifth fasciculi of M. rectus capitis
superior, and dorsal tip of hyoid cartilage.
Origin. In two parts, both fleshy, at opposite ends of
muscle. Anterior origin from posterolateral edge of skull
bordering posterior edge of temporal fossa and extending to
base of opisthotic process, in a narrow line 8 mm long, just
posteroventral to origins of deep slip of M. adductor
mandibulae externus superficialis and rostral slip of M. ad-
ductor mandibulae externus profundus. Anterior origin sepa-
rates origins of latter two muscles from both anterior edge
of origin of M. depressor mandibulae and anteroventral edge
of origin of M. cucullaris, cephalic part.
Posterior origin is in common with M. tracheohyoideus
as result of fusion of the two muscles. Common sheet origi-
nates from narrow line along anterolateral edge of ventral
three-fourths of furculum, extending to mid-ventral line.
From this origin the sheet runs anterodorsad onto the neck.
Insertion. By connective tissue, onto skin of neck, by
all but anterior 10-18 mm of length of muscle. Fuses medi-
ally with M. tracheohyoideus at ninth or tenth cervical ver-
tebra to form common sheet. Posterior to fusion the common
sheet covers neck, except in narrow area along middorsal and
mid-ventral lines. A few short bundles, arising from furcu-
lum, leave dorsomedial edge of muscle near its posterior end
and insert on skin of neck near middorsal line.
Action. Tenses skin of neck.
Comparisons. In the Gruidae the muscle undergoes change.
In Balearica it is similar to the condition just described in
Aramus, but the belly is much thinner. Grus is apparently
unique in lacking the furcular origin and in having a very
short belly. The condition of the muscle in Grus might well
be re-examined, since the three specimens used by Fisher and
Goodman were skinned before dissection, and also because the
posterior regions are very thin and difficult to see.
In the Rallidae the anterior origin differs distinctly
from the condition described for Aramus and the cranes by
arising from the postorbital process. In Rallus the poste-
rior origin comes mainly from the anterior edge of M. pec-
toralis and the anteroventral corner of the sternum, but in
Fulica it arises mainly from the sternum and sternoclavicular
ligament (in Aramus it arises mainly from the furculum). In
Rallus (and Aramus) the posterior origin is dorsal to the
origin of M. tracheohyoideus, with the bellies of the two
muscles closely fused, but in Fulica the posterior origin is
ventral to the origin of M. tracheohyoideus, and the bellies
are only weakly fused.
Summary. The muscle in Aramus is long and has two ori-
gins. In the cranes, Balearica agrees, but in Grus it has
become extremely shortened and has lost the posterior origin.
In the rails the muscle is long with both origins present,
but the anterior origin lies further forward on the skull.
2. M. cucullaris, cephalic part
Moderately thin sheet. Covers posterior edge of skull
and dorsolateral portion of anterior fourth of neck. At-
taches to skull, to third, fourth, and fifth cervical verte-
brae, and to underlying muscles.
Right and left muscles essentially fused into single
sheet by continuation of fascia on superficial and deep sur-
faces. These fascial sheets enclose between them the paired
anterior belly of M. biventer cervicis. Muscle lies deep to
M. dermo-temporalis. Lateral portion contacts posterodorsal
edges of third, fourth, and fifth fasciculi of M. rectus
capitis superior, posterodorsal edge of M. depressor
mandibulae, and anterodorsal corner of M. rectus capitis
lateralis. Superficial to M. splenius capitis, M. splenius
accessorius, Mm. intertransversarii between axis and fourth
cervical, and to anterior portion of M. spinalis cervicis.
Origin. By tendinous sheet from dorsolateral surface
of a dorsal tubercle on diapophysis of fourth cervical verte-
bra and by fleshy origin from similar location on third cer-
vical. Also originates by fleshy fibers from bony, lateral
bar connecting prezygapophysis with postzygapophysis on
third and fourth cervicals, by small portion arising from
fifth cervical, and by fleshy fibers from Mm. intertrans-
versari and from third, fourth, and fifth fasciculi of
M. rectus capitis superior.
Insertion. Mainly by fibrous sheet, about 3 mm long,
onto thin, transverse line on dorsal and lateral edges of
occipital region of skull, about 1 mm dorsal to insertion of
M. biventer cervicis on occipital crest. Insertion extends
laterad from middorsal line, then ventrad to meet and fuse
with most dorsal portion of M. depressor mandibulae. Fuses
by loose fibers to dorsal edge of M. rectus capitis
lateralis, to anterior regions of M. cucullaris and M.
splenius capitis, and contacts dorsal edge of anterior region
of origin of M. dermo-temporalis.
Action. One muscle extends head dorsolaterally, and
both act together to extend head dorsally.
Comparisons. In the Gruidae the attachments in Balearica
are quite similar to those of Aramus and are partly so in
Grus, although Fisher and Goodman omitted some details be-
cause of obscuring fascial attachments. The fusion to M.
rectus capitis lateralis and M. depressor mandibulae is
present in Balearica but absent in Grus because the belly is
The Rallidae agree with Aramus except in attachments to
adjacent muscles. In Rallus the contact with M. depressor
mandibulae is smaller than in Aramus because of partial sep-
aration by M. rectus capitis lateralis. In Fulica the mus-
cle contacts neither M. rectus capitis lateralis nor M. de-
Summary. The muscle attaches to M. depressor mandibulae
and M. rectus capitis lateralis in Aramus, Balearica, and
Rallus, but in the more specialized Grus and Fulica there is
no contact with these muscles because the belly is narrower.
3. M. biventer cervicis
Very narrow and elongate, composed of two bellies con-
nected by flattened tendon. Lies just lateral to middorsal
line along all except posterior end of neck. Attaches to
skull anteriorly, to fascia and to M. spinalis cervicis
Anterior belly begins just posterior to skull and ex-
tends to about middle of third cervical. Muscle continues
as tendon from middle of third cervical to middle of ninth
cervical, where posterior belly begins. This belly extends
to about posterior end of thirteenth cervical, where muscle
again becomes tendinous. Fibrous connections join right and
left muscles across mid-line at level of posterior end of
thirteenth and at posterior end of fourteenth cervicals.
Right and left members lie alongside each other, sepa-
rated by middorsal line, and anterior bellies fuse in crani-
al half. Anterior belly enclosed within fascial sheets of
M. cucullaris, cephalic part. Most of muscle posterior to
M. cucullaris lies in trough along dorsomedial edge of M.
spinalis cervicis. Connects to latter muscle only at poste-
rior end, but is tightly held against it by strong sheet of
connective tissue enclosing both. Anterior end of muscle
lies superficial to M. splenius capitis and to portions of
Mm. splenii colli.
Origin. By thin tendon, entirely from dorsal surface
of median portion of tendinous area of M. spinalis cervicis
near posterior end of fourteenth cervical.
Insertion. By short but wide aponeurosis from cranial
end of anterior belly, onto thin edge of occipital crest of
skull, just deep to insertion of cephalic part of M. cucul-
laris and in contact with dorsal edge of insertion of M.
splenius capitis. Tendon strong in most medial one-sixth,
weaker laterally. Medial edge meets that of opposite muscle
at middorsal line.
Action. Extends head and straightens neck.
Comparisons. In the Gruidae the posterior belly is lo-
cated between the twelfth and fifteenth cervicals (between
ninth and thirteenth in Aramus). In Balearica the right and
left anterior bellies are fused in less than the anterior
fourth (in the anterior half in Aramus) and apparently are
not fused at all in Grus. In Balearica (and Aramus) the
anterior belly is enclosed between the fascial layers of the
cephalic part of M. cucullaris, but in Grus the anterior
belly is completely deep to that muscle. In both cranes the
tendon of origin is fused to the tendon of M. spinalis
cervicis but can be traced to an attachment on the eighteenth
cervical in Balearica and on the sixteenth in Grus (in Aramus
the origin can be traced only to the tendon). In both cranes
the insertion is partly fleshy and quite narrow, representing
only the stronger, medial portion of the inserting tendon of
In the Rallidae the posterior belly in Rallus is located
between the fifth and tenth cervicals, and in Fulica between
the seventh and eleventh. In both rallids the right and left
anterior bellies are fused only at the extreme anterior end.
In both rails (and in Aramus) the anterior belly is enclosed
within the cephalic part of M. cucullaris. In both rallids
the muscle arises fleshily from M. spinalis cervicis (ten-
dinously in Aramus). In both rails the insertion is much
narrower and more medial than in Aramus.
Summary. The location of the posterior belly in the
limpkin is intermediate between that of the cranes and rails,
probably because of size differences. The extent of fusion
between right and left anterior bellies is greatest in Aramus,
intermediate in Balearica, least in the rallids, and appar-
ently lacking in Grus. The wide, lateral extension of the
insertion is unique in the limpkin.
4. M. splenius capitis
Wide and thick anterior end tapers to small posterior
end, giving triangular appearance in dorsal view. Occupies
most of dorsal half of extreme anterior end of neck. At-
taches to skull, to axis, and to surrounding muscles.
Two muscles of pair partially connected across mid-line.
Most of muscle lies deep to cephalic part of M. cucullaris,
and small ventrolateral portion covered by M. depressor
mandibulae and M. rectus capitis lateralis. Lies dorsal to
region of fusion of second to fifth fasciculi of M. rectus
capitis superior. Superficial to all of first and anterior
end of second Mm. interspinales, and to anterior one-third
of M. splenius accessorius.
Origin. Fleshy and tendinous, primarily from axis and
atlas and from fascia connecting atlas to skull, with some
tendinous origin from dorsal raphe of connective tissue,
slightly posterior to axis. Much of origin arises from
neural spine of axis, by small and tendinous anteromedial
components and by mixed fleshy and tendinous components from
anterolateral face of neural spine. Remainder of origin
fleshy, from dorsal surface of atlas and fascia anterior to
atlas, and almost contacts insertion.
Insertion. On all but ventromedial portion of occipital
region of skull, including part of membrane closing occipital
fontanelle, extending onto depression on opisthotic process.
Deeper portions of insertion fleshy, with more superficial
components tendinous. Bordered dorsally by insertion of
M. biventer cervicis; some fibrous connection to overlying
anterior end of cephalic part of M. cucullaris. Partly fused
laterally to underside of insertion of M. rectus capitis
lateralis, which in turn is fused to underside of origin of
M. depressor mandibulae. Bordered ventrolaterally by ventro-
medial portion of origin of M. depressor mandibulae, and has
some fleshy insertion on posterodorsal region of belly of
Action. One muscle turns head, but two act together to
extend head dorsally.
Comparisons. In the Gruidae the thickness and insertion
of the muscle in Balearica are as in Aramus, but in Grus the
belly is thinner, and the area of insertion correspondingly
narrower. In Balearica, but not in Grus (or Aramus), a par-
tial separation is present in the posterior end. In Balearica
only, the muscle fuses to M. splenius accessorius. Only Grus
lacks the fusion of the muscle to M. rectus capitis lateralis.
In both cranes the muscle differs from that of Aramus in
arising from fascia over the atlas instead of directly from
the atlas and from fascia directly anterior to it. Both
cranes differ from Aramus in lacking the portion of the ori-
gin posterior to the axis. In Balearica the origin fiom the
spine of the axis is narrowly restricted to the mid-line, but
in Grus (and Aramus) it is wider.
In the Rallidae the belly is thinner than in Aramus,
especially in Fulica. Both rails agree with the limpkin in
the connections of the muscle to adjacent ones. In both
rallids the origin from the axis is much narrower than in
Aramus, being restricted to the area of the mid-line. The
remainder of the origin agrees in Rallus and Aramus, but in
Fulica it arises from fascia over the axis, and the portion
posterior to the axis is absent.
Summary. Of the seven variations in this muscle listed
above, the two cranes agree in only two points and are simi-
lar to each of the other three forms in at least as many.
The two rails agree in only four, and the greatest number of
similar points (six) occurs between Aramus and Rallus.
Aramus has the least agreement with Balearica. The sporadic
distribution of characters seems to indicate adaptability in
5. M. splenius accessorius
Small, elongate, and flattened. Runs diagonally on
dorsolateral aspect of anterior region of neck. Attaches to
first three cervical vertebrae.
Although Fisher and Goodman considered this muscle as
being probably related to M. splenius capitis, it may be
more closely related to M. spinalis cervicis-Mm. splenius
Anterior half deep to M. splenius capitis, and poste-
rior half deep to M. biventer cervicis and M. cucullaris,
cephalic part. Contacts dorsal edge of first of Mm. inter-
transversarii. Anterior portion superficial to lateral edge
of first M. interspinalis and to posteromedial portion of
second fasciculus of M. rectus capitis superior. Posterior
portion superficial to posterolateral part of second M. inter-
spinalis and to tendinous insertion and part of belly of an-
terior end of M. spinalis cervicis-Mm. splenius colli complex.
Origin. Mixed fleshy and tendinous from anterolateral
side of neural spine of third cervical, and from dorsolateral
extent of postzygapophysis of axis. Origin loosely attached
along posterolateral edge to adjacent anterior belly of an-
teriormost part of Mm. splenius colli.
Insertion. Anterior third of muscle comprised of thin,
strap-like tendon which attaches to posterior process of
postzygapophysis of atlas. Underside of belly has fleshy at-
tachment to dorsolateral extent of postzygapophysis of axis,
and this area of attachment considered to have functional
components of both origin and insertion.
Action. Turns upper end of neck laterad.
Comparisons. In the Gruidae, Balearica has the muscle
thoroughly attached to M. splenius capitis and M. spinalis
cervicis, but in Grus (and Aramus) these attachments are
slight or lacking. In Balearica the muscle arises and in-
serts on the axis in a manner more complex than in Aramus,
but in Grus these attachments are absent. In Balearica the
main insertion is not on the postzygapophysis of the atlas
(as it is in Aramus) but is on the dorsal half of the neural
arch. In Grus this is the only insertion, which Fisher and
Goodman (1955) describe as being on the most ventral and lat-
eral extent of the atlas. This origin differs remarkably
from all other forms studied, unless the arch of the atlas
In the Rallidae the belly of the muscle in Rallus lies
between the third cervical and the axis, and passes medial to
the postzygapophysis of the axis. In Fulica the belly lies
between the axis and atlas and passes lateral to the post-
zygapophysis of the axis. In both rallids the insertion onto
the axis is larger than in Aramus, and this is the main in-
sertion in Rallus. In both rallids the atlantal insertion
is on a facet on the postzygapophysis instead of on a defi-
nite process as in Aramus.
Summary. This muscle is somewhat variable in detail,
especially within the cranes and to a lesser extent between
the gruids and Aramus. The two rails show good agreement
with each other and with the limpkin. Balearica resembles
Aramus slightly more than does Grus, and Fulica is more like
the limpkin than is Rallus.
6. M. depressor mandibulae
Short, somewhat thick, and partially separated into lat-
eral and medial parts. Located at angle of jaw. Attaches to
skull and to posterior end of mandible.
Deep, in part, to anterior end of M. dermo-temporalis
and to dorsal edge of M. geniohyoideus. M. splenius capitis
has part of insertion on posterolateral extent of median
part, and portion of posterodorsal edge fused with M. cucul-
laris. Anteroventral edge contacts posterior end of M.
stylohyoideus and contacts posterior edge of superficial
part of M. pteryqoideus ventralis on both lateral and medial
sides of mandible. Anterodorsal edge of belly fused to wall
of external auditory meatus. Superficial to anterior ends
of M. rectus capitis lateralis, M. rectus capitis superior
complex, and to Liqamentum mandibulae.
Origin. Arises from skull, mainly from region of
opisthotic process. Origin and belly incompletely divided
into lateral and medial parts by inserting aponeurosis of M.
rectus capitis lateralis. Lateral portion composed of fleshy
fibers arising from ventrolateral region of occipital crest,
along posterior edge of anterior origin of M. dermo-temporalis,
and these fibers fuse with aponeurosis of M. rectus capitis
lateralis. Medial portion has mixed origin from posteroven-
tral surface of opisthotic process. Anterior to separation
by M. rectus capitis lateralis, two portions join with fleshy
origin from all but lateral surface of opisthotic process,
with strong tendon from anterior edge of opisthotic process,
and with tendinous fibers from ventrolateral edge of basi-
temporal plate. Lateral and medial portions of muscle remain
partially separable through middle of belly.
Insertion. Fleshy, except for tough, superficial
fascial sheet. Attaches to most of posterior face of mandible.
Action. Opens mouth by depressing mandible.
Comparisons. In the Gruidae the muscle differs from
that of Aramus in contributing to the origin of M. dermo-
temporalis and in having much less connection to M. rectus
capitis lateralis. In Balearica the origin extends to the
dorsal edge of the occipital region of the skull, and the
belly is slightly fused to the insertion of M. splenius
capitis. In Grus (and Aramus) the origin does not extend so
far dorsad, and it does not connect to the insertion of M.
splenius capitis. Balearica resembles Aramus but differs
from Grus in having part of the origin from the basitemporal
In the Rallidae the muscle in Rallus is divided into
anterodorsal and posteroventral portions, unlike the divi-
sion into lateral and medial portions in Fulica (and Aramus).
In both rallids the muscle resembles that of Aramus in not
contributing to the origin of M. dermo-temporalis or fusing
to the insertion of M. splenius capitis. Both rallids differ
from Aramus in having part of the origin from the basitemporal
plate and in having no fusion of the muscle to the cephalic
part of M. cucullaris.
Summary. Only minor variations are present, and points
of comparison indicate that Aramus has similarities to both
cranes and rails.
7. M. rectus capitis lateralis
Thick, fleshy, horizontally oriented sheet at posterior
end tapers to much narrower, vertically oriented aponeurosis
at anterior end; runs from posteroventral to anterodorsal
locations. Lies on side of anterior end of neck. Attaches
to second, third, and fourth cervicals and to skull.
Anterodorsal end lies partly deep to anterior portion
of M. dermo-temporalis, to ventrolateral corner of insertion
of cephalic part of M. cucullaris, and to a posterodorsal
portion of lateral part of M. depressor mandibulae.
Posteroventral end partly covered by anterior end of M. flexor
colli brevis. A short length of dorsal edge is fused to ven-
tral edge of cephalic part of M. cucullaris near anterior
ends of the two muscles. Ventral side of belly very loosely
connected to dorsal side of M. rectus capitis ventralis.
Posterior portion contacts M. flexor colli profundus. At
anterior end muscle lies superficial to ventrolateral edge
of origin of M. splenius capitis and to posterodorsal extent
of medial origin of M. depressor mandibulae. Middle of bel-
ly superficial to portions of last three fasciculi of M.
rectus capitis superior.
Origin. Arises by fleshy and tendinous fibers from
ventrolateral edges of hypopophyses of second, third, and
fourth cervicals. At extreme posterior end has some fleshy
fusion to M. rectus capitis ventralis, and origins of two
Insertion. By thin aponeurosis, mostly in common with
lateral part of M. depressor mandibulae, onto narrow line on
ventrolateral portion of occipital crest and extending onto
posterolateral edge of opisthotic process. Most of attach-
ment lies adjacent to posterior edge of anterior origin of
M. dermo-temporalis. Insertion separates origin of M. de-
pressor mandibulae into lateral and medial parts. Dorsal
tip of insertion lies deep to ventrolateral edge of cephalic
part of M. cucullaris, near its insertion, and anterior half
of dorsal border loosely joined by connective tissue to lat-
ter muscle, although bellies not in contact.
Action. One muscle acts to turn head laterad, and both
together extend (beugung of Gadow, 1893) head on neck.
Comparisons. In the Gruidae the attachment in Balearica
to M. rectus capitis lateralis is as in Aramus, except for
being weaker. In Grus a strong attachment exists between
these two muscles, but only on the left side. The asymmetry
is apparently correlated with the position of the trachea.
Both cranes differ from Aramus in having none of the muscle
deep to or fused with the cephalic part of M. cucullaris and
none superficial to M. depressor mandibulae. In Balearica
the origin from the second through the fifth cervicals, but
in Grus only from the third and fourth cervicals (in Aramus
it arises from the second through the fourth). In Balearica
the insertion is as in Aramus, attaching to a long line by a
thin, wide aponeurosis, but in Grus a thickly rounded tendon
inserts on a small oval facet. Both gruids differ from
Aramus in lacking a common insertion with M. depressor
In the Rallidae the connection to M. rectus capitis
ventralis is symmetrical, but it is stronger in Fulica. In
both rallids then fusion to M. cucullaris and the connection
to M. depressor mandibulae are stronger than in Aramus.
Summary. Variations among the three families are slight.
Minor characteristics of Aramus agree well in Balearica, but
poorly in Grus. The Rallidae are rather constant and agree
well with Aramus.
8. M. rectus capitis superior
Relatively thick and composed of five fasciculi, appear-
ing in lateral view as an elongate triangle with apex at pos-
terior end. Located on side of upper neck. Attaches to
first five cervicals, to skull, and to parts of M. flexor
colli brevis and M. flexor colli profundus.
First four fasciculi diverge from small, common ante-
rior end, but fifth largely independent. Each successive
fasciculus attaches to cervical vertebra of corresponding
numbers, although third and fifth have additional attach-
ments. Successive fasciculi, therefore, of increasing thick-
ness and length from anterior to posterior ends. Separations
between last three fasciculi indistinct in one specimen.
Fourth fasciculus partly superficial to fifth, and some
fleshy connection exists between them. Much of muscle com-
plex lies deep to M. rectus capitis lateralis. Most of dor-
sal edge of complex adjoins first five Mm. intertransversarii
and ventrolateral edge of cephalic part of M. cucullaris.
More posterior portions dorsal to posterior portions of M.
rectus capitis lateralis and M. flexor colli brevis. Super-
ficial to all but posterior end of M. flexor colli brevis,
to anterior end of M. longus colli, and to anterior end of
M. flexor colli profundus.
Origin. First fasciculus arises fleshily from side of
atlas, between dorsolateral border of condylar facet and in-
sertion of M. splenius accessorius on posterior process of
postzygapophysis. Second fasciculus originates fleshily and
tendinously from side of axis, along bony ridge extending
from prezygapophysis to postzygapophysis. Third fasciculus
has fleshy and tendinous origin, similar to that of second,
from lateral bar of third cervical, but has additional
fleshy origins from fused rib of third cervical and from
centrum of second cerfical. Fourth fasciculus also has
mixed origin from whole length of lateral bar of fourth cer-
vical and from fused rib of same vertebra. Fifth fasciculus
arises fleshily from side of axis and from large areas on
fused ribs of third and fourth cervicals, alongside origins
of previous two fasciculi. Fifth fasciculus arises also
from lateral bars of third and fourth cervicals and from side
of prezygapophysis of fifth cervical. Small, deep slip arises
in common with main part of fifth fasciculus and with M.
flexor colli brevis. All fasciculi but first have some of
origin in contact with adjacent portions of Mm. intertrans-
versarii, and all but first and second fasciculi have origins
connected to ventrolateral portions of origin of cephalic
part of M. cucullaris. Fifth fasciculus loosely connected
at posterior end to M. flexor colli brevis.
Insertion. Fasciculi one through four have common in-
sertion, by small tendon, onto triangular area on postero-
lateral region of basitemporal plate; this surface of at-
tachment faces posteroventrally. Fifth fasciculus has inde-
pendent tendinous insertion on posteriorly directed process
from ventrolateral part of atlas, small attachment to hy-
papophysis of axis, and small deep slip that passes sepa-
rately to attach to first fasciculus of M. flexor colli
profundus, which inserts on pleurapophysis of axis.
Action. One muscle turns head and upper neck ventro-
laterad, but both muscles together bend head and upper neck
Comparisons. In the Gruidae Balearica is unique in
having the third fasciculus divided into two parts. In
Balearica the origins for fasciculi three, four, and five
are on a ligament alongside the centra of the vertebrae in-
volved (this ligament is ossified in Aramus), but in Grus
the ligament is apparently absent, and the fasciculi arise
from the centrum. Balearica agrees with Aramus in having
several origins for each of these three fasciculi, but Grus
has few. In Balearica the deep slip of the fifth fasciculus
is divided into outer and,inner parts, but only one exists
in Grus (and Aramus). The inner part in Balearica inserts
independently and seems to correspond to the single slip of
the others; the outer part inserts with the main fifth
fasciculus, from which it is apparently derived. In Balearica
and Grus the main insertion is partly on fascia connecting to
the skull (directly to the skull in Aramus). The muscle in
Grus is unique in having a common insertion with M. flexor
In the Rallidae the origins of fasciculi three, four,
and five have fewer attachments, especially to pleurapophyses,
than in Aramus. In Rallus the fifth fasciculus is short and
is completely deep to the third and fourth, but at least
part of the fifth is exposed in Fulica largelyy exposed in
Aramus). In Rallus the fifth fasciculus has no origin from
the fifth cervical, but some of the origin arises from that
vertebra in Fulica (and Aramus). The fifth fasciculus in the
rallids lacks the deep slip found in Aramus. In Rallus the
fifth fasciculus inserts independently as in Aramus, but a
common insertion with M. flexor colli brevis exists in
Fulica. Individual variation was found in one specimen of
Rallus, in which the third and fourth fasciculi were in-
separably fused on one side.
Summary. The inconstancy of the muscle indicates
adaptability. The Rallidae are unique in lacking the deep
slip of the fifth fasciculus. Evidences of additional
separation (in Balearica) and fusion (in Rallus) of fasciculi
indicate that these slips probably evolved from a single,
larger muscle, and rearrangement is still occurring.
9. M. rectus capitis ventralis
Elongately triangular, with slightly wider anterior end
tapering uniformly to pointed posterior end; composed of
lateral and medial parts. Located on ventral side of neck
in region of throat. Attaches to first five cervicals, to
connective tissue in mid-line, loosely to surrounding mus-
cles, and to skull.
Lateral part has irregular, transverse partition of
connective tissue in middle of belly, causing muscle to ap-
pear to be formed by fusion of ends of two shorter muscles.
Medial part composed of loosely connected bundles.
Lateral part longer and partly superficial to medial
part. Right and left lateral parts loosely connected poste-
rior to medial part. Right and left medial parts in contact
throughout length at mid-ventral line, strongly fused at an-
terior ends. Lateral and medial parts mostly very loosely
connected, but somewhat fused near insertions. Muscle lies
just dorsal to esophagus, with portion of posterior end deep
to M. longus colli. Lateral side of muscle contacts medial
side of M. rectus capitis lateralis and M. longus colli, and
posterior end of each part contacts M. rectus capitis supe-
rior. Medial part contacts an anterior portion of insertion
of M. flexor colli profundus.
Origin. Lateral part arises fleshily from ventral face
of hypapophysis of fourth cervical, ventral surface of
centrum of fifth cervical, and from connective tissue around
carotid artery ventral to sixth cervical. Medial part takes
fleshy and tendinous origin from narrow area along mid-
ventral line, including hypapophyses and fascia between
hypapophyses, of first four cervical vertebrae. Lateral
part has some connection to M. lonqus colli at posterior end.
Origin of medial part loosely connected to medial side of
origin of M. rectus capitis lateralis, to an anterior portion
of insertion of M. flexor colli profundus, and appears to be
continuous with its own insertion on skull.
Insertion. Lateral part inserts by narrow, rounded
tendon onto small tubercle (probably same as occipital pro-
cess of Fisher and Goodman, 1955) on posterolateral area of
basitemporal plate. Medial part inserts fleshily on larger
area, including nearly all of ventral surface of basitem-
poral plate. Lateral and medial parts somewhat fused near
Action. Flexes head on neck.
Comparisons. In the Gruidae the muscle is symmetrical
in Balearica (and Aramus) but isasymmetrical in Grus. The
transverse partition in Aramus is lacking in both gruids.
Balearica resembles Aramus in having the two lateral parts
only weakly connected. In Grus the right and left medial
parts are inseparably fused, and the two lateral parts are
much more closely connected than in Balearica (or Aramus).
In Balearica the attachment to M. rectus capitis lateralis
is symmetrical and slightly stronger than in Aramus, but in
Grus it is much stronger on the left side and absent on the
right. In Balearica (and Aramus) the lateral part originates
bilaterally from the fourth and fifth cervicals and connec-
tive tissue below the sixth. In Grus the right lateral part
arises from the fourth and sometimes the fifth cervicals, but
the left one arises from the fourth, fifth, and sometimes the
sixth cervicals. In Balearica (and Aramus) the origin of
the medial part is from the skull to the fourth cervical.
In Grus the left medial part agrees, but the right only ex-
tends posteriad to the third cervical. In Balearica (and
Aramus) the insertion of the lateral part is located further
posterior than in Grus. This attachment is elongate in
Balearica and oval in Grus (rounded in Aramus).
In the Rallidae the muscle is symmetrical in Rallus,
but the right lateral part is sometimes longer in Fulica
(this asymmetry is opposite to that of Grus). Neither rallied
has the transverse partition of Aramus. In Rallus the poste-
rior extent of the lateral part reaches the connective tis-
sue ventral to the sixth cervical, but only reaches to the
region of the fifth cervical in Fulica.
Summary. Minor features are inconsistent within the
cranes, consistent within the rallids, with better agreement
with Aramus. The limpkin agrees best with Balearica in the
cranes and with Rallus in the rails. The inconsistency
within the gruids is apparently a consequence of the special-
izations in Grus, involving asymmetry and coiling of the
trachea. Slight asymmetry sometimes occurs in Fulica, but
it is opposite to that of Grus.
10. M. flexor colli brevis
Elongately triangular, with apex at posterior end; ob-
liquely divided into four separate fasciculi. Located on
lateral portion of upper neck. Attaches onto second through
seventh cervicals, to M. longus colli, to Mm. intertransversarii.
and loosely to M. rectus capitis superior.
Anterior half located deep to M. rectus capitis superior,
and edges of posterior portion partly deep to Mm. intertrans-
versarii. Partly in common with anterior end of M. lonqus
colli. Ventral portions contact origins of M. rectus capitis
lateralis. Superficial to most of M. flexor colli profundus
and portions of Mm. intertransversarii.
Origin. First and most anterior fasciculus originates
fleshily from lateral surface of centrum of third cervical
and fleshily from lateral bar of fourth cervical. Second
fasciculus takes fleshy origin from prezygapophysis and lat-
eral surface of centrum of fifth cervical. Third fasciculus
arises from postzygapophysis of fifth cervical. Fourth
fasciculus has origin from pleurapophysis of sixth and an-
terolateral corner of prezygapophysis of seventh cervical.
Three posterior parts loosely connected to Mm. intertrans-
Insertion. First fasciculus inserts partly along poste-
rior edge of pleurapophysis of third cervical and remainder
fuses with fifth fasciculus of M. rectus capitis superior.
Second fasciculus inserts on pleurapophysis of third cervi-
cal in common with portions of M. longus colli. Third fas-
ciculus inserts on distal tip of pleurapophysis of fourth
cervical. Fourth fasciculus inserts on pleurapophysis of
fifth cervical and sometimes on distal end of pleurapophysis
of fourth cervical.
Action. One muscle bends upper neck ventrolaterad, but
both together turn upper neck ventrad.
Comparisons. In the Gruidae Balearica has the muscle
divided into fasciculi as in Aramus. Divisions are apparently
similar in Grus, but Fisher and Goodman (1955) did not list
them in detail. In Grus a portion of the most anterior fas-
ciculus arises from the axis and the third cervical and in-
serts on the fifth fasciculus of M. rectus capitis superior,
but this fasciculus is an inseparable part of M. rectus
capitis superior in Balearica (and Aramus). The anterior
portion of the muscle has apparently changed its associa-
tions. This supports the idea of Fisher and Goodman (1955)
that M. flexor colli brevis could be considered as slips of
the M. rectus capitis superior complex. The second and third
fasciculi in Balearica (and Aramus) apparently represent di-
visions of a single fasciculus arising from the fifth cervi-
cal in Grus. Both cranes disagree with Aramus in having a
portion originating from the pleurapophysis of the fifth
cervical. In Balearica (and Aramus) the origin has compo-
nents, not present in Grus, from the fourth and seventh
In the Rallidae the muscle is divided as it is in Aramus.
Both rallids differ from Aramus in possessing, as part of M.
flexor colli brevis, the portion that arises from the atlas
and third cervical and attaches to the fifth fasciculus of
M. rectus capitis superior. In Rallus only, a small portion
arises from the fifth cervical. In Fulica (and Aramus) por-
tions arise from the fourth and seventh cervicals, but in
Rallus the origin from the seventh is lacking.
Summary. The major features of this muscle are funda-
mentally similar but show considerable variation in the ar-
rangement of the parts among the three families, as well as
within the Gruidae and the Rallidae. In some small details
of attachment there is greater similarity between Aramus and
Balearica than between Balearica and Grus. Intrafamilial
variation, along with distinct interfamilial similarity, in-
dicates that this muscle has been variously specialized in
11. M. flexor colli profundus
A disjunct series of six fasciculi connecting anterior
vertebrae. Located on ventrolateral side of upper neck. At-
taches to first six cervicals, to M. lonqus colli, and to
M. rectus capitis superior.
Most of muscle lies deep to M. flexor colli brevis, and
small middle portion deep to M. rectus capitis superior.
Posterior end deep to M. longus colli, and third fasciculus
deep to one of Mm. intertransversarii. Ventral extent in
contact with medial part of M. rectus capitis ventralis and
posterior portion of M. rectus capitis lateralis.
Origin. First two fasciculi closely connected. First
fasciculus arises from anteroventral edge of pleurapophysis
of third cervical. Second fasciculus arises from medial side
of pleurapophysis and anteroventral corner of centrum of
third cervical. Third fasciculus has fleshy and tendinous
origin from anteromedial edge of pleurapophysis of fourth
cervical, from lateral part of centrum and hypapophysis of
third cervical, and loosely from medial side of pleurapophy-
sis of third cervical. Fourth fasciculus arises fleshily or
by strong, narrow tendon from anterior face of prezygapophy-
sis of fifth cervical and fleshily from lateral side of cen-
trum and medial side of pleurapophysis of fourth cervical.
Fifth fasciculus has mostly fleshy origin from anterior
corner of ventrolateral portion of sixth cervical and fleshy
origin from ventrolateral edge of full length of centrum of
fifth cervical. Sixth fasciculus arises, mostly tendinously,
from sixth cervical, just ventral to and in contact with
origin of fifth fasciculus pnd partly in common with origin
of one of fasciculi of M. longus colli.
Insertion. First fasciculus receives medial slip of
fifth fasciculus of M. rectus capitis superior and inserts
tendinously on pleurapophysis of axis. Second fasciculus
inserts fleshily on most of lateral face of hypapophysis of
axis and on ventral extent of atlas. Third fasciculus has
mixed insertion along ventrolateral edge of hypapophysis of
axis. Fourth fasciculus has fleshy insertion onto postero-
lateral portion of hypapophysis of third cervical. Fifth
fasciculus inserts on posterior corner of ventrolateral re-
gion of centrum of fourth cervical. Sixth fasciculus has
fleshy insertion onto ventrolateral edge of full length of
centrum of fifth cervical but may also insert with fifth
fasciculus on fourth cervical. Insertions of third and
fourth fasciculi contact origin of M. rectus capitis lat-
eralis. Insertion of fifth fasciculus contacts origin of
medial part of M. rectus capitis ventralis and part of in-
sertion of M. lonqus colli.
Action. Contraction of muscle on one side bends upper
neck in ventrolateral direction, but both sides together bend
upper neck in ventral direction.
Comparisons. In the Gruidae, Balearica agrees with
Aramus in having the first two fasciculi fused, but in Grus
they are separate. In Balearica the fifth and sixth fas-
ciculus each have a connection to a portion of M. loncus
colli, but in Grus only the fifth is so connected (neither
connection exists in Aramus). The third fasciculus in
Balearica originates from the centrum, but not from the hy-
papophysis or pleurapophysis of the third cervical; all
three origins are present in Grus (and Aramus). In Balearica
(and Aramus) the fourth fasciculus arises partly from the
pleurapophysis of the fourth cervical, but this origin is
not found in Grus. In Balearica the third fasciculus has an
additional deep portion that inserts on the whole lateral
face of the hypapophysis of the third cervical, but in Grus
(as in Aramus) this portion is not present, and the insertion
of the third fasciculus is only on the axis.
In the Rallidae the first two fasciculi differ fmrm the
ones in Aramus in being separate. In Rallus the third fas-
ciculus has a connection to M. longus colli, not present in
Fulica (or Aramus). The fifth and sixth fasciculi are sep-
arate in Rallus (and Aramus), but they are strongly connected
in Fulica. In Rallus (as in Aramus) the insertions of the
first and second fasciculi occupy nearly all of the lateral
face of the hypapophysis of the axis, but these insertions
occupy only very small areas in Fulica. In Rallus the fifth
fasciculus is large and inserts partly on the third cervical,
whereas this part is smaller and has no insertion on the
third cervical in Fulica (or Aramus).
Summary. The variations in this muscle among the genera
are slight, but inconsistent within the Gruidae and Rallidae.
The divergences primarily involve small variations in fas-
cicular attachments of the various parts.
12. M. adductor mandibulae
Wide and flat in posterior third; narrow and somewhat
thickened in anterior two-thirds. Runs longitudinally along
lateral portion of skull. Attaches to temporal fossa, to
mandible, to M. depressor mandibulae, and to deeper adductor
Bridged over by postorbital ligament and jugal bar of
skull. Ventral edge of posterior half closely attached to
dorsal edge of rostral slip of M. adductor mandibulae ex-
ternus profundus, fused to anterior side of posterodorsal
extent of M. depressor mandibulae and contacts anterior ori-
gin of M. dermo-temporalis. Superficial to M. adductor
mandibulae externus medialis and M. adductor mandibulae
Origin. Arises fleshily from posterior two-thirds of
temporal fossa, and also by ossified tendon continuous with
bone of ventral portion of temporal fossa. Ventral edge of
origin arises from tendon of origin of M. adductor mandibulae
Insertion. Two separate insertions. One mainly fleshy,
on superficial fascia and ossified tendon of most lateral
part of M. adductor mandibulae medius, with superficial fas-
cia extending farther to insert directly on bone of mandible
along anterodorsal edge of latter muscle. Other part of
insertion attaches onto coronoid process of mandible, by
very strong tendon partly in common with insertion of M. ad-
ductor mandibulae externus medialis.
Action. Closes mouth by adducting mandible.
Comparisons. In the Gruidae the muscle in Balearica is
undivided as in Aramus, but in Grus it is composed of sepa-
rate superficial and deep parts. In Balearica the muscle is
separated from M. depressor mandibulae, but it has intimate
contact with the anterior origin of M. dermo-temporalis.
Grus agrees with Aramus in having the muscle contact M. de-
pressor mandibulae, but in neither is there close contact
with M. dermo-temporalis. In Balearica a narrow, ossified
tendon originates from the ventral portion of the temporal
fossa in common with M. adductor mandibulae medius (the ten-
don is similar but separate in Aramus). This tendon corres-
ponds to the independent, unossified, main origin of the su-
perficial part in Grus, and the remainder of the origin of
the superficial part in Grus is from fascia of the deep part.
The other origin in Balearica (and Aramus) arises fleshily
from most of the temporal fossa and corresponds to the fleshy
origin of the deep part from the dorsoposterior region of the
temporal fossa in Grus. In both cranes the most anterior in-
sertion is by a strong tendon (unlike the weak and super-
ficial fascia attachment in Aramus) on the dorsolateral edge
of the mandible. This is the insertion of only the super-
ficial part in Grus. In Balearica, but not in Grus, there
is a small area (large in Aramus) of fleshy attachment to
M. adductor mandibulae medius, just posterior to the previous
tendon. The deeper and more posterior insertion on the coro-
noid process of the mandible is similar in both cranes and
agrees with Aramus, but this is the insertion of only the
deep part in Grus.
In the Rallidae the muscle is divided in the posterior
region into two heads that seem generally equivalent to the
superficial and deep parts in Grus. Fulica is unique in
having some of the deep head superficial to the superficial
head, and in showing individual variation in the size of the
muscle, so that it is sometimes superficial to part of M.
adductor mandibulae externus profundus. In both rallids the
muscle has more extensive contact with M. depressor mandibulae
than in the limpkin, and the posterior portion is overlapped
by M. dermo-temporalis (not overlapped in Aramus) In Rallus
alone, this origin is enclosed by superficial fascia, by
which it is attached to the deep head. The deeper origin in
both rallids is about the same as that of Aramus. In both
Rallus and Fulica (but not in Aramus) each of the two heads
arises partly from M. adductor mandibulae externus medialis.
In both rallids the two heads fuse before inserting. The
most anterior attachment is similar to the corresponding at-
tachment in Aramus, except that it is located more poste-
riorly and lacks attachment to M. adductor mandibulae medius.
Summary. The muscle apparently has undergone several
small-scale modifications in the various genera. It is com-
posed of only one part in Aramus and Balearica, but it is
composed of two parts in Grus and is partly divided in the
rallids. The most distinctive feature is the small, tendinous
origin of the superficial part in Aramidae and Gruidae, con-
trasted with the wide and fleshy attachment of the corres-
ponding origin in Rallidae. In other more minor features
Aramus has more similarity with gruids than with rallids.
13. M. adductor mandibulae
Small, elongate muscle composed of rostral and caudal
parts; rostral part superficial with bipinnate belly. Poste-
rior end of muscle lies just posterior to ear opening. An-
terior end passes beneath postorbital ligament and beneath
posterior end of jugal bar. Attaches to temporal fossa,
quadrate, mandible, and to tendon of origin of lateral part
of M. adductor mandibulae medius.
Anterior end partly deep to lateral part of M. adductor
mandibulae medius. Posterior end in contact with ventral
edge of M. adductor mandibulae externus superficialis and
with anterior origin of M. dermo-temporalis. Middle of belly
attaches to ventral side of tendon of origin of lateral part
of M. adductor mandibulae medius. Superficial to most of
medial part and some of origin of lateral part of M. adduc-
tor mandibulae medius.
Origin. Rostral part arises, partly fleshily and partly
by ossified tendon, from ventral region of temporal fossa,
fleshily from lateral surface of quadrate, and by ossified
tendon from otic process of quadrate. Dorsal edge of origin
arises from tendon of origin of M. adductor mandibulae medius.
Caudal part arises fleshily from lateral surface of main body
of quadrate and from proximal part of orbital process of
quadrate, in common with portion of origin of rostral part.
Insertion. Rostral part has mixed insertion, partly by
ossified tendon and partly by fleshy fibers, onto dorsolat-
eral edge of mandible. This attachment partly deep to, and
partly posterior to, insertion of lateral part of M. adduc-
tor mandibulae medius, to which there is some connection.
Caudal part inserts partly fleshily and partly by ossified
tendon, attaching strongly onto dorsal edge of mandible at
level of small foramen in angular bone.
Action. Closes mouth by adducting mandible.
Comparisons. In the Gruidae the muscle in Balearica is
divided, but the superficial part is small and seems to cor-
respond to the upper, tendinous portion of the rostral part
in Grus (and Aramus). The deeper part in Balearica includes
portions corresponding to all the caudal part as well as to
the deeper and more ventral portions of the rostral part of
Grus (and Aramus). This muscle in Balearica is neither con-
nected to nor covered by M. adductor mandibulae medius (con-
nected but not covered in Aramus). In Grus the dorsal end of
the caudal part is fused to the medial slip of the previous
muscle, and the anteroventral portion of the rostral part is
covered by the lateral part of the same muscle. In Grus,
but not Balearica (or Aranus), the dorsal end of the rostral
part is covered by the deep slip of M. adductor mandibulae
In the Rallidae the muscle is slightly smaller than in
Aramus. In Rallus the rostral and caudal parts are entirely
fused, and in Fulica they are separate only at their inser-
tions (fused only at origins in Aramus). Fulica shows in-
dividual variation in sometimes having the dorsal edge of the
rostral part deep to M. adductor mandibulae externus super-
ficialis, because of variation in the size of the latter
muscle. In Rallus and Fulica (but not in Aramus) the origin
of the rostral part includes portions from the orbital cra-
nium, just medial to the postorbital process.
Summary. Balearica appears somewhat specialized in
having the two parts separated in a different plane from that
of Grus and the non-gruids. In other minor features the
rallids are different from the non-rallids in having the
muscle smaller and in having the two parts mostly fused, al-
though a small amount of similar fusion occurs in Aramus.
The two rallids are also distinct from the other two families
in having the origin extending into the orbit.
14. M. adductor mandibulae
Composed of thin and somewhat spatulate lateral part and
thicker medial part. Located below eye; lateral part one of
most superficial adductors of jaw, medial part deepest adduc-
tor of jaw. Attaches to temporal fossa, to quadrate, to
mandible, and to inserting tendon of M. adductor mandibulae
Bridged by postorbital ligament and jugal bar. Tendon
of origin of lateral part deep to adjacent edges of
M. adductor mandibulae externus superficialis and rostral
part of M. adductor mandibulae externus profundus, where
these two muscles adjoin. Dorsal half of anterior end deep
to and fused with M. adductor mandibulae externus super-
ficialis. Medial part deep to all other adductors of jaw.
Most ventral extent of lateral part contacts superficial part
of M. pterygoideus ventralis. Posterior end of lateral part
superficial to portion of caudal part of M. adductor man-
dibulae externus profundus. Anterior end of lateral part
superficial to anterior end of rostral part of M. adductor
mandibulae externus profundus and to most posterior insertion
of M. adductor mandibulae externus superficialis.
Origin. Lateral part arises by slender, ossified ten-
don from anteroventral extent of temporal fossa. This ten-
don also furnishes part of dorsal edge of origin of rostral
part of M. adductor mandibulae externus profundus and ventral
edge of origin of M. adductor mandibulae externus super-
ficialis. Muscle narrow in proximal third, then belly and
an enclosed ossified tendon flare to become wide and fleshy
in anterior two-thirds. Medial part has mixed origin from
anterior edge of body and anterior and anteromedial edges of
orbital process of quadrate.
Insertion. Lateral part inserts fleshily over region
about 23 mm long, including mandibular foramen. Posterior
edge of insertion on anterior end of rostral part of M.
adductor mandibulae externus profundus, and M. adductor man-
dibulae externus superficialis shares dorsal part of inser-
tion. Medial part inserts narrowly on posterolateral edge
of mandible just anterior to quadrate and extensively onto
large depression on medial side of mandible. Covers area
from internal articular process to posterior third of mandi-
bular foramen. Tendon of M. pseudotemporalis passes through
medial part, which it partially divides along superficial
side. Tendon of M. adductor mandibulae externus medialis
inserts on anterodorsal edge of medial part.
Action. Closes mouth by adducting mandible.
Comparisons. In the Gruidae the muscle in Balearica
differs fron'that of Aramus in lacking contact with M. ptery-
goideus ventralis, but the contact sometimes exists in Grus.
In Balearica the lateral part is unique in having a large
ossified tendon of origin in addition to the smaller ossi-
fied tendon like that of Grus (and Aramus) and in having a
dense fascial sheet that covers the lateral edge of the
medial part and fuses with the inserting tendon of M. pseudo-
temporalis. Balearica (like Aramus) has no origin of this
muscle from the lateral face of the quadrate, but that area
furnishes a portion of the origin of the medial part in Grus.
In the Rallidae the proximal end of the lateral part is
located farther dorsally and is deep only to M. adductor
mandibulae externus superficialis (in Aramus this portion is
deep to the .latter muscle as well as to M. adductor mandibulae
externus profundus, since it lies beneath the line of junc-
tion between them). The two rallids have only the dorsal
edge of the lateral part deep to the anterior end of M. ad-
ductor mandibulae externus superficialis and have no insertion
of that muscle on the lateral part (in Aramus most of the
dorsal half of the lateral part lies deep to M. adductor
mandibulae externus superficialis and furnishes a wide area
of insertion for it). The rallids differ from Aramus in
having the tendinous portion of the origin of the lateral
Summary. In Aramus the muscle agrees somewhat better
with that of Grus than Balearica, but the variations are
mostly minor. The most distinctive characters are the extra
tendon of origin of the lateral part and the dense, lateral
fascia in Balearica, but these apparently are specializa-
tions, since they are not found in Grus or Aramus. The dif-
ferences between the limpkin and the Rallidae are similarly
minor, and the two rallids agree closely, even in small
15. M. adductor mandibulae
Small and elongate muscle. Deepest of adductors in
temporal fossa; located just ventral to orbit. Attaches to
temporal fossa, to M. adductor mandibulae externus super-
ficialis, and indirectly to mandible.
All but anterodorsal edge of muscle deep to anterodorsal
edge of middle of belly of M. adductor mandibulae externus
sunerficialis. Superficial to belly of M. pseudotemporalis
bulbi and to posterodorsal part of origin of M. pesudo-
Origin. Arises partly fleshily and partly by ossified
tendon arising as continuation of bone of temporal fossa.
Origin covers small area in anterodorsal region of temporal
fossa, just posterior to posterodorsal part of origin of M.
Insertion. Belly attaches to ossified tendon of M. ad-
ductor mandibulae externus superficialis and inserts in com-
mon with it on coronoid process of mandible and on anterodor-
sal edge of medial part of M. adductor mandibulae medius.
Muscle therefore inserts indirectly on mandible.
Action. Aids in closing mouth by adducting mandible.
Comparisons. In the Gruidae, Balearica has the origin
larger and more completely aponeurotic than in Grus (or
Aramus). In Balearica the side of the muscle is completely
fused to the inner side of M. adductor mandibulae externus
superficialis, and the insertion is on the same muscle (the
small insertion is the only attachment to that muscle in
Aramus). In Grus there is no attachment to M. adductor
mandibulae externus superficialis, and the insertion is en-
tirely on M. adductor mandibulae medius.
In the Rallidae the belly of the muscle in Rallus lies
between the two parts of M. adductor mandibulae medius, but
does not in Fulica (or Aramus). In Rallus, but not in Fulica
(or Aramus), there is fusion to the dorsal edge of the rostral
part of M. adductor mandibulae externus profundus. In both
rallids (and in Aramus) the insertion is on M. adductor
mandibulae externus superficialis. In Rallus only, there is
an additional, more direct connection to the mandible.
Summary. This muscle in Aramus has some differences
from the corresponding muscle in both Balearica and
Grus, and some differences are found between the two cranes.
The insertion on M. adductor mandibulae medius is similar in
Balearica and Aramus, but in Grus it is on a different mus-
cle. The muscle shows some minor differences between the
two rallids, but in Fulica and Aramus the muscle agrees well.
16. M. pseudotemporalis
Rather pyramidal muscle with flat planes of anterior and
lateral faces oriented at right angles to each other distal
third comprised entirely of narrow, ossified tendon. Located
in anterior region of temporal fossa, posterior and ventral
to postorbital process, and in orbit, medial to postorbital
process. Attaches to temporal fossa, orbit, and to mandible.
Portion of origin from temporal fossa deep to M. adductor
mandibulae externus medialis and to posterior end of M. ad-
ductor mandibulae externus superficialis, although very small
portion of dorsal edge visible dorsal to latter muscle in
some specimens. Much of lateral face of muscle deep to belly
of M. pseudotemporalis bulbi. Distal end of muscle deep to
belly of M. adductor mandibulae externus superficialis and to
tendinous insertion of rostral part of M. adductor mandibulae
externus profundus. Tendon of insertion partly superficial
to, and partly enclosed by, medial part of M. adductor man-
Origin. Arises fleshily from anterodorsal corner of
temporal fossa, from medial surface of postorbital process,
and from area occupying about one-fourth of posterior wall of
orbit, just medial to postorbital process. Proximal end of
muscle covered by stzrng superficial fascia which adds ten-
dinous component to origin.
Insertion. Ossified tendon forms within belly near prox-
imal end of muscle and extends anteroventrad to become sole
insertion, attaching to medial aide of mandible onto tubercle
in posterior part of depression for insertion of M. adductor
Action. Aids in closing mouth by adducting mandible.
Comparisons. In the Gruidae the origin from the tem-
poral fossa in Balearica is more extensive than in Grus (or
Aramus). In Balearica the inserting tendon bifurcates, and
one portion inserts on the fascia of M. adductor mandibulae
medium, while the other turns anteriorly and inserts on the
mandible. Grus resembles Aramus in having an undivided in-
serting tendon and in having the insertion independent and
entirely on the mandible. Both cranes differ from Aramus in
not having the inserting tendon penetrate the medial part of
M. adductor mandibulae medius.
In the Rallidae the origin from the temporal fossa is
lacking (present in Araus), and the orbital origin is larger
than in Aramus, occupying about half the posterior wall.
The two rallids differ from Aramus in having the inserting
tendon bifurcated, unossified, and not penetrating M. ad-
ductor mandibulae medium.
Sumnry. The Rallidae are distinct from the other two
families in having the origin arising almost entirely from
the orbit and in lacking the portion from the temporal fossa,
which is a large portion of the origin in the limpkin and is
the main origin in the cranes. Bifurcation in the inserting
tendon has perhaps arisen independently in Balearica and the
rails, since no such division occurs in Aramus or Grus.
17. M. pseudotemporalis bulbi
Small, strap-like muscle of soft texture and brownish
coloration. Located in anteroventral region of temporal
fossa aid posterolateral region of orbit. Attaches to cra-
nium, to muscle on posterior wall of orbit, and to connec-
tive tissue associated with lacrimal gland.
Ventral end deep to portions of M. adductor mandibulae
externus superficialis, M. adductor mandibulae externus
medialis, and lateral part of M. adductor mandibulae medius.
Middle of belly superficial to middle of lateral face of M.
Origin. Arises fleshily from narrow, small area of
cranium ventral to foramen ovale, just medial to dorsal edge
Insertion. Muscle terminates, just medial to postorbi-
tal process, with fleshy attachment to posteroventral part of
lacrimal gland, by attachment of connective tissue fibers
onto muscle tissue superficial to anterior face of M. pseudo-
temporalis, and by attachment onto fascia covering postero-
ventral surface of eyeball.
Action. Uncertain; may pull on lacrimal gland and
thereby aid in discharging its secretions.
Comparisons. In the Gruidae, the origin in Balearica
is from the anterior edge of the temporal fossa, and in Grus
it arises from an area of the temporal fossa slightly dorsal
to that of Balearica (in Aramus it arises from a location
just anteroventral to the temporal fossa). In Balearica the
origin is posteroventral to the origin of M. pseudotemporalis,
but posterior to that origin in Grus (and ventral to it in
In the Rallidae this muscle is essentially the same as
Summary. There is only a slight difference between the
two cranes in the location of the origin of this muscle, and
both are slightly different from Aramus. Otherwise the mus-
cle in the cranes is quite like thatof.Aramus, and in the
rallids the whole muscle is essentially the same as in the
18. M. pterygoideus ventralis
Large jaw muscle forming an elongate triangle with lar-
ger end posterior; divided except at insertion into super-
ficial and deep layers. Muscle covers all except dorsal
surface of posterior end of mandible and extends dorsad to
occupy region dorsal to buccal cavity. Attaches to mandi-
ble, to pterygoid, and to palatine.
The variability in the pterygoid muscles in closely re-
lated species was shown by Lakjer (1926) and is corroborated
in this study. Fisher and Goodman (1955) state that all
parts of their 4. pteryqoideus ventralis and M. pterygoideus
dorsalis may arise embryologically from a single muscle mass,
and some workers have synonymized all parts as components of
one muscle (Edgeworth, 1935, M. adductor mandibulae internus;
Gadow, 1893, Mm. pteryqoidei). From the similar orientation
of the bundles in Grus (Fisher and Goodman, 1955, fig. 7) it
seems more reasonable to include the lateral part of M.
pteryqoideus dorsalis with M. pterygoideus ventralis, and that
part is in fact fused with the adjacent part of M. ptery-
goideus ventralis in all the genera dissected in this study.
The classification of Fisher and Goodman is retained
here, for convenience, in spite of its artificial nature.
However, the terminology of the attachments is reversed,
since the pterygoids and palatines are more effectively
moved by contraction of these muscles than is the mandible.
Posterior end on both lateral and medial sides of man-
dible lies deep to muscle sheet composed of M. stylohyoideus
and M. constrictor colli, and portion along medial edge of
mandible deep to M. geniohyoideus. Posterior end contacts
edge of insertion of M. depressor mandibulae, and portion on
lateral side of mandible contacts posteroventral edge of in-
sertion of lateral part of M. adductor mandibulae medius.
Side of deep layer apparently fused to entire length of lat-
eral part of M. pterygoideus dorsalis. Superficial to in-
sertion of medial part of M. adductor mandibulae medius on
medial side of mandible. Deep layer superficial to medial
part of M. pterygoideus dorsalis and to M. protractor ptery-
goideus. Superficial layer superficial to all of deep layer
except a portion of lateral edge on ventral side.
Origin. Superficial layer arises partly fleshily and
partly by flattened, ossified tendon, from posteroventral
corner of lateral face of mandible. Additional fleshy and
tendinous origins arise from lateral, ventral, and medial
edges of posterior face of mandible. Portion of origin on
medial side of mandible common to both superficial and deep
layers. This origin is mostly fleshy but includes several
ossified tendons attaching to dorsomedial tip of internal
Insertion. Superficial layer inserts fleshily on entire
ventrolateral trough of palatine, tendinously on ventral and
posterior edges of ventrolateral wing of palatine, and flesh-
ily on ventral surface of medial end of pterygoid. Deep
layer inserts fleshily on dorsolateral surface and ten-
dinously on dorsomedial edge of palatine.
Action. Retracts palatine and pterygoid and depresses
Comparisons. In the Gruidae the deep layer in Balearica
(and Aramus) is simple, but in Grus it is further divided
into distinct lateral and medial parts. The superficial
layer in Grus is uniquely specialized in having a strong,
silvery aponeurosis over its insertion. In both cranes the
superficial layer is superficial to all of the deep layer
(to all but the lateral edge of the deep layer in Aramus).
In Balearica (and Aramus) the lateral surface of the deep
layer is completely fused to M. pterygoideus dorsalis but is
entirely separate in Grus. In Balearica (and Aramus) most of
the portion on the lateral surface of the mandible is covered
by M. stylohyoideus and M. constrictor colli, but very little
of this portion is covered by M. stylohyoideus and none by
M. constrictor colli in Grus. In Balearica the superficial
and deep layers are fused at the origins and along their
lateral edges (in Aramus the two layers are fused only at
their origins), but in Grus the two layers originate sep-
arately. Balearica (and Aramus) have a single insertion of
the superficial layer, but there are two separate insertions
in Grus. Balearica, and apparently Grus, differ from Aramus
in lacking ossified tendons in the origin.
In the Rallidae, the muscle in Rallus (and Aramus) is
composed of a superficial layer and a single deep layer, but
in Fulica the portion corresponding to the lateral part of
the deep layer of Grus is distinct, and the bundles corres-
ponding to the medial part of the deep layer are fused into
one muscle with the superficial layer.
In Fulica alone some of the muscle is deep to the ante-
rior, free portion of M. geniohyoideus, as a result of greater
thickness and more posterior attachment of that muscle.
Summary. For the details discussed above, Balearica
and Grus show little agreement, but Aramus and Balearica are
quite similar. The division in the deep layer in Grus repre-
sents the most striking specialization, and a somewhat simi-
lar specialization is present in Fulica. The muscle in Rallus
is quite like that of Aramus and differs from that of Fulica
mainly in the connections of the various portions.
19. M. pterygoideus dorsalis
Medium-sized and flattened muscle, oblanceolate in lat-
eral view; partially divided into dorsal and ventral divi-
sions. Located just anteromedial to angle of jaw. Attaches
to mandible, to pterygoid, and to palatine.
Lies deep to M. pteryqoideus ventralis. Adjoins poste-
rior edge of insertion of medial part of M. adductor mandibulae
medius and posterior edge contacts M. protractor pterygoideus.
Origin. Arises fleshily from wide area of medial and
dorsomedial part of mandible, between posterior edge of in-
sertion of M. adductor mandibulae medius and posterior edge
of mandible. Dorsomedial portion of origin occupied by
partially distinct dorsal section.
Insertion. Inserts tendinously and fleshily on all but
posterior surface of pterygoid. Partially separated dorsal
division inserts on posterior end of palatine, just anterior
to previous attachment.
Action. Depresses upper jaw by retracting palatine and
Comparisons. In the Gruidae, the muscle in Balearica
(and Aramus) is simple, but in Grus it is comprised of dis-
tinct lateral and medial parts. The representative of the
lateral part in Balearica (and Aramus) is apparently com-
pletely fused into the lateral edge of the deep layer of M.
pterygoideus ventralis, and the medial part represents the
sole remnant of the muscle in this crane. In Balearica (and
Aramus) the muscle is partially divided into dorsal and
ventral sections, but no division occurs in the corresponding
part in Grus. In Balearica (and Aramus) the origin extends
from the medial onto the dorsomedial portion of the mandible,
but the corresponding part in Grus arises only from the medial
side. In Balearica (and Aramus), but not in Grus, a portion
of the insertion is on the dorsal side of the pterygoid.
In the Rallidae the muscle differs from that of Aramus
in having no evidence of the partial separation of the muscle
into dorsal and ventral sections and no attachment to the
palatine. In Rallus (and Aramus) the origin does not over-
lap the deep part of M. adductor mandibulae medius, but in
Fulica the origin is wider and overlaps the posterior edge
of the deep part of that muscle.
Summary. Grus seems specialized since the points by
which it differs from Balearica are strikingly alike in
Aramus and Balearica, and even like those in the two rallids.
Grus alone has a separate lateral part, and the partial di-
vision of the muscle in Aramus and Balearica is not found in
the corresponding, medial part in Grus. In Aramus and Rallus
the muscle is nearly identical, and differs only slightly in
20. M. protractor pterygoideus
Small muscle composed of sheet-like ventral part and
somewhat thicker dorsal part. Ventral part located poste-
rior to pterygoid; dorsal part located just posterodorsal to
pterygoid and posteroventral to orbital process of quadrate.
Attaches to basitemporal plate, to ventrolateral region of
orbit, and to pterygoid.
Anterior extent of ventral part in contact with M.
pteryqoideus dorsalis and partly deep to posterior edge of
M. pterygoideus ventralis. Dorsal part ventral to M. pro-
Origin. Ventral part arises fleshily from anterolateral
area of basitemporal plate, adjacent to anterior edge of in-
sertion of medial part of M. rectus capitis ventralis. Dor-
sal part originates from lateral depression in basisphenoid
and from adjacent ventromedial area of orbit just antero-
medial to origin of M. protractor quadratus.
Insertion. Ventral sheet inserts fleshily along medial
edge of entire length of pterygoid bone. Dorsal sheet has
mostly fleshy insertion on posterodorsal side of posterior
end of pterygoid bone.
Action. Raises maxilla by pulling pterygoid forward.
Comparisons. In the Gruidae the muscle is composed of
only one part (definite dorsal and ventral parts in Aramus),
and the insertion is on the anterior third of the pterygoid
(on the full length of the pterygoid in Aramus).
In the Rallidae (as in Aramus) the muscle is in two dis-
tinct parts, and the ventral sheet inserts on the full length
of the pterygoid. In Rallus the dorsal part is enclosed by
fleshy fibers of M. protractor quadratus, but the same part
is ventral to that muscle in Fulica (and Aramus). In Rallus
the dorsal part is wide at its origin and inserts by a slender
but strong tendon. In Fulica (and Aramus) the origin of this
part is narrower, and the insertion is fleshy and wider.
Summary. The cranes are distinct from the limpkin and
the rails in having the muscle undivided, with a more re-
stricted insertion. Rallus appears specialized in having
the dorsal part enclosed, with a wide origin and a narrow and
tendinous insertion. In Aramus and Fulica the enclosure of
the dorsal part is lacking, the origin is narrower, and the
insertion is wider and fleshy.
The stronger insertion in Rallus may be associated with
feeding habits, such as gaping under pressure when the bill
is probed into mud, but a corresponding enlargement of M.
depressor mandibulae, as occurs in some passerines with strong
gaping adaptations (Beecher, 1951a), is lacking.
21. M. protractor quadratus
Small, thick muscle composed of very short fibers. Lo-
cated in small space between cranium and orbital process of
quadrate. Attaches to cranium and to quadrate.
Deep to belly of M. pseudotemporalis. Dorsal to lateral
portion of dorsal part of M. protractor pterygoideus, and
posterior to medial portion of same muscle.
Origin. Arises fleshily from area of cranium immediately
medial to orbital process of quadrate. Origin includes small
section of posteroventral region of orbit. Medial extend of
origin posterior to, and in contact with, medial extend of
origin of dorsal part of M. protractor pterygoideus.
Insertion. Has fleshy insertion on entire medial surface
of orbital process of quadrate.
Action. Raises maxilla by rotating lower end of quad-
Comparisons. In the Gruidae the origin in Balearica
(and Aramus) is larger and more ventrally located than in
Grus. The insertion in Balearica (and Aramus) is on all of
the medial surface of the orbital process of the quadrate,
but on only the posterior edge of the medial surface of that
process in Grus.
In the Rallidae the muscle in Rallus encloses the dorsal
part of M. protractor pterygoideus but is located entirely
dorsal to that muscle in Fulica (and Aramus).
Summary. The differences in the muscle in the two
cranes are very slight, but a closer resemblance between
Aramus and Balearica is apparent, in spite of the small dif-
ferences involved. Rallus appears more specialized in having
the muscle located farther ventrally than in Fulica or Aramus,
as a result of which is partially encloses another protractor
This may also be associated with gaping adaptations,
since the muscle aids in opening the mouth by raising the
Muscles of the Hyoid
22. M. constrictor colli
Thin, partly double, dermo-osseous sheet with orienta-
tion of bundles anteromedial at anterior end, changing to
posteromedial and then to transverse along neck. Posterior
bundles loosely connected and gradually fade out posteriorly.
Extends from anterior end of basihyal bone posteriad across
throat, and lines skin of entire neck, nearly to posterior
end. Attaches to mandible, to connective tissue in mid-line,
to M. stylohyoideus, to M. dermo-temporalis, and to skin.
This muscle may include the posterior sheet of M. mylo-
hyoideus (also called M. serpio-hyoideus), which Fisher and
Goodman (1955) stated could not be found in Grus americana.
Fused to other member of pair by connective tissue in
mid-line. Extreme anterior end deep to M. intermandibularis.
Superficial on mandible to M. pterygoideus ventralis and to
hyoid and tracheal muscles in region of throat. Superficial
to posterior edge of M. dermo-temporalis and to M. tracheo-
hvoideus through most of length of neck.
Origin. Arises by two sheets that join at posteroven-
tral corner of mandible. One sheet attaches to superficial
and one to deep side of posterior edge of mandible. Deep
sheet arises in common with M. stylohyoideus, in contact with
insertion of M. depressor mandibulae. Both sheets superfi-
cial to origin of M. pterygoideus ventralis.
Insertion. In region of throat inserts on connective
tissue in mid-line and loosely onto skin. Posterior to man-
dible transverse bundles insert only on skin.
Action. Constricts and raises musculature of throat
and hyoid apparatus, and constricts skin on ventral side of
Comparisons. In the Gruidae the sheet is thinner than
in Aramus. In Balearica it has fewer contractile components
than in Aramus, and in Grus it has even fewer muscular fibers.
In Balearica the muscle arises by a deep fascial sheet and a
superficial muscular sheet, but in Grus only one sheet is
present (Aramus has two sheets, both muscular). In the cranes
only the superficial sheet contributes to the origin of M.
stylohyoideus (in Aramus both sheets contribute equally to
that origin). In both cranes the muscle lies between the
posterior end of the basihyal bone and the seventh cervical
(in Aramus it extends from the anterior end of the basihyal
nearly to the posterior end of the neck). In Balearica (and
Aramus) the muscle gradually fades into the skin posteriorly,
but in Grus it ends more abruptly on tracheal fascia and
In the Rallidae the contractile content of the muscle is
equal to that of Aramus, and in Fulica the thickness is even
greater. The division into two sheets is similar in both
rallids, but the inner one is weaker in Rallus. In Rallus
only the deep sheet, and in Fulica only the superficial sheet,
contributes to the origin of M. stylohyoideus. In both ral-
lids the bundles just posterior to the jaw pass further dor-
sad than in Aramus and even reach the mid-dorsal line in the
region of the frontal bones. In the two rails the anterior
end of the muscle is located more posteriorly than in Aramus,
lying about 5 mm posterior to the posterior end of the basi-
hyal bone. In both rallids the muscle ends on the skin of
the neck, but in Rallus it extends about half the length of
the neck, and in Fulica it extends the-full length.
Summary. This constrictor sheet is well developed in
Aramus and Rallus and is highly developed in Fulica. It is
reduced in the cranes, especially in Grus. The deep sheet
of the origin is better developed in Aramus than in the ral-
lids and entirely lacks contractile fibers in the gruids.
In the limpkin the anterior end of the muscle is anterior to
the position in the cranes and considerably anterior to that
in the two rallids. In the cranes the muscle sheet barely
extends onto the neck, but covers at least half the neck in
the other three genera. This constrictor sheet appears to
have been variously modified in the species studied, but in
extent and development the muscle in Aramus finds somewhat
better agreement in the rallids than in the gruids.
23. M. intermandibularis
Thin muscle sheet with bundles oriented essentially
transversely and gradually becoming indistinct at anterior
end. Located between rami of mandible. Attaches to mandible,
to connective tissue in mid-line, and loosely to skin.
Fused to other member of pair by connective tissue in
mid-line. Posterolateral edge deep to anterior end of M.
geniohyoideus. Superficial to M. genioglossus, and posterior
end superficial to anterior ends of M. constrictor colli and
Origin. Takes fleshy origin from dorsomedial edge of
mandible on line extending from gonys to about level of mid-
dle of basihyal bone.
Insertion. Inserts in mid-line on same connective tis-
sue to which M. constrictor colli attaches, on line extending
posteriad from gonys to point 10 mm beyond posterior end of
Action. Raises anterior hyoid musculature and floor of
Comparisons. In the Gruidae the muscle is quite reduced,
being composed of a very thin contractile sheet in Balearica
and having only a few muscular fibers in Grus (in Aramus the
entire sheet is muscular and thicker). In Balearica contrac-
tile fibers are indistinct in the anterior half of the bill
and in Grus are not present at all except at the posterior
end of the sheet. In Balearica the posterior end of the ori-
gin is slightly anterior to that of Aramus, but the posterior
end of the insertion is considerably posterior to that point
in Aramus, being about even with the posterior end of the
In the Rallidae the thickness and contractile nature of
the muscle agrees with that of Aramus, but the muscle is
thicker in Fulica. In both rallids the muscle sheet becomes
thinner, with its anterior regions more closely attached to
the skin than in Aramus. In both rallids the posterior ends
of the origin and the insertion are located slightly posterior
to the corresponding locations in Aramus.
Summary. This muscle is quite reduced in the gruids,
especially so in Grus. It is well developed in Aramus and
the rallids, especially in Fulica. The position of the poste-
rior edge of the muscle in Aramus is intermediate between
that of the cranes and that of the rails. In Aramus and the
gruids the anterior end of the sheet is more closely attached
to skin than in the rallids. The differential development of
this muscle in the three families is parallel to that of M.
constrictor colli, and as is found in the latter muscle,
Aramus agrees better with the rallids than with the gruids.
24. M. geniohyoideus
Very elongate, thin band of muscle. Located mainly be-
neath floor of mouth along medial side of mandible, but ex-
tends posteriad around posteroventral corner of mandible to
lie along posterolateral edge of cranium. Attaches to man-
dible, to floor of mouth, and to thyrohyals.
Middle of belly deep to M. constrictor colli, and pos-
terodorsal tip deep to M. dermo-temporalis. Anterior half
superficial to lateral edge of M. intermandibularis, and mid-
dle of belly superficial to ventral side of M. pterygoideus
ventralis. Posterior portion superficial to portion of M.
ceratoglossus, and posterodorsal portion passes over YF.
rectus capitis ventralis and M. rectus capitis lateralis.
Origin. Arises fleshily from elongate area along dorso-
medial side of ramus of mandible. Extends from level of
posterior end of mandibular foramen to about level of anterior
half of nostril, lying just ventral to origin of M. inter-
mandibularis. Posterior end of attachment lies between M.
pterygoideus ventralis and mandible.
Insertion. Posterior end passes onto greater cornu of
hyoid, partially encloses ceratohyal, attaches loosely to
posterior end of that bone and to anterior end of epihyal,
and finally inserts fleshily onto entire surface of poste-
rior end of epihyal and its cartilaginous extension.
According to Fisher and Goodman (1955) the mandibular
attachment is the insertion, and the thyrohyal attachment is
the origin. Since the latter attachment is the more movable,
it is considered here as the insertion and the mandibular
attachment as the origin.
Action. Protracts tongue by pulling hyoid apparatus
Comparisons. In the Gruidae, Balearica is unique in
having an additional small lateral slip that arises from the
lateral face of the mandible. The gruids differ from Aramus
in having the muscle connect to M. dermoalossus. but this un-
ion is inconstant in Grua. In Balearica the origin of the
main slip is long and extends slightly farther anteriorly
than in Aramus, but in Grus this attachment (called inser-
tion by Fisher and Goodman, 1955) is much shorter. In
Balearica (and Aramus) the posterior end encloses the cerato-
hyal but attaches only loosely to the posterior end. In
Grus this attachment is more extensive, as is the epihyal
attachment (called origin by Fisher and Goodman, 1955). The
small lateral slip, present only in Balearica, fuses with
the main slip at the side of the distal end of the insertion.
The individual variation mentioned for this muscle in Grus
is not found in Aramus.
In the Rallidae a small lateral slip is found in Rallus
but not in Fulica. Both rallids agree with Aramus in lacking
connection of the muscle to M. dermoglossus. The combined
origin of the two slips, from the lateral face of the man-
dible, is short and deep in Rallus and corresponds to the
origin of the single slip in Fulica (in Aramus a single ori-
gin is also present, but it is very much longer and shal-
lower and comes from the medial side of the mandible). In
both rallids the enclosure of the ceratohyal and the inser-
tion on the epihyal are both similar to conditions in Aramus.
The small slip in Rallus fuses with the posterir end of the
insertion of the main slip.
Summary. This muscle agrees in the cranes and the
limpkin in having a rather long, shallow origin, whereas in
the rallids the origin is very short but deep. It seems
that the more anterior extension would allow greater protrac-
tion of the tongue in the cranes and the limpkin. The divi-
sion into two slips seems to have arisen independently, but
strikingly similarly, in Balearica and Rallus. The small
lateral slip could act to pull the distal end of the cornu
laterad and perhaps to brace the protracted tongue.
25. M. stylohyoideus
Very long, narrow group of bundles arising as anterodor-
sal edge of sheet of M. constrictor colli. Located in ventro-
lateral region of throat. Attaches to mandible, to M. con-
strictor colli, and to entoglossum.
Anterior end deep to M. constrictor colli, M. interman-
dibularis and M. genioqlossus. Posterior end fused with both
sheets of M. constrictor colli, and anterior half lies
alongside M. ceratoglossus lateralis. Posterior end super-
ficial to posterior end of M. ceratoglossus inferior and to
M. pterygoideus ventralis. Middle of belly passes over M.
Origin. Arises as part of both sheets of M. constrictor
colli, from dorsomedial and dorsolateral corners of posterior
edge of mandible.
Insertion. Separates from M. constrictor colli as it
passes under ventral edge of mandible and follows side of M.
ceratoglossus lateralis to insert fleshily on tendon of that
muscle and on posterolateral corner of entoglossum.
Action. One muscle turns tongue laterad, but both to-
gether retract tongue and perhaps raise it.
Comparisons. In the Gruidae the muscle in Balearica is
much thinner and flatter than in Grus (or Aramus). In
Balearica the origin merges imperceptibly with M. constrictor
colli, but in Grus (and Aramus) it appears as separate mus-
cle. In both cranes the muscle agrees with that of Aramus
in arising partly from the mandible, but differs in having
no origin from the medial side. Grus is unique in having a
portion arise from the opisthotic process. In Balearica a
part of the insertion (and all of the insertion in Aramus)
is on the posterolateral corner of the entoglossum, but the
remainder of the insertion in Balearica is on the dorsolat-
eral portion of the anterior end of the basihyal. In Grus
the insertion is on the most anterolateral surface of the
ceratohyal, at the articulation between that bone and the
basihyal. The more posterior location of the insertion in
Grus would result in less effective movement of the tongue,
so that the main function in this genus is apparently re-
traction of the hyoid apparatus.
In the Rallidae the muscle in Rallus is small and band-
like as in Aramus, but in Fulica it is very thick and some-
what rectangular in cross section. In Rallus (and Aramus)
the muscle originates partly from both sheets of M. constric-
Ia colli, but no connection with that muscle is present in
Fulica, in which the origin is entirely from the side of the
posterior end of the mandible. In Rallus the anterior end
of the muscle is variable but usually divides into two por-
tions, one inserting on the anteromedial extent of the
ceratohyal and the other usually inserting on the dorsal side
of the posterior portion of the basihyal bone, although this
anterior insertion is sometimes on the ceratohyal, just an-
terior to the previous one. In Fulica the bundles of the
anterior end of the ceratohyal and the posterior end and lat-
eral side of the basihyal (in Aramus it inserts on the ento-
glossum). In both rallids the action is probably retraction
of the whole hyoid, rather than direct movement of the tongue
as in Aramus. The larger muscle in Fulica indicates a strong-
Summary. This muscle is variable and apparently quite
subject to specialization among the genera studied. The
shape and size of the belly are nearly uniform in the genera
other than Fulica, in which the muscle is considerably larger.
The origin is from both lateral and medial faces of the man-
dible in the limpkin and in Rallus, but arises only from the
side in Fulica and the gruids. The variable insertion is
similarly located in Aramus and Balearica, but it is much
farther posterior in Grus and the rallids. In view of the
more anterior insertion, it seems that the main function in
Aramus and Balearica is to move the tongue laterad and raise
it, but in Grus and the rallids it must retract the hyoid
26. M. genioglossus
This muscle sheet is not present in Aramus, and no con-
tractile fibers are found in the membranous floor of the
mouth. M. intermandibularis, largely absent or reduced to
fascia in Grus, is well developed in Aramus and lies just
superficial to the presumed location of M. genioglossus.
The former sheet has an origin similar to that described for
the latter muscle, but its insertion is not on the floor of
the mouth or the entoglossum, and therefore it is an entirely
different muscle, even though it probably has a somewhat
Comparisons. In the Gruidae, the muscle is absent in
Balearica but present in Grus. In Grus the muscle is a thick,
widely triangular sheet, the lateral edge of which lies be-
tween M. geniohyoideus and the floor of the mouth. It arises
from a small area on the inner side of the mandible, dorsal
to the insertion of M. geniohyoideus, and flares widely to
insert on the floor of the mouth and on the posterior half
of the entoglossum. The anterior ends of the corresponding
right and left muscles meet in the mid-line of the ento-
glossum. The apparent function of the two muscles is to
raise the tongue and floor of the mouth, although one muscle
alone could turn the tongue laterad.
The absence of the muscle in Balearica, compared to the
presence in Grus, may be correlated with the more anterior
insertion of M. stylohyoideus, for lateral movement of the
tongue, in Balearica (and Aramus). In Grus that insertion
is considerably posterior to the tongue, but a similar func-
tion is apparently served in that crane by M. genioglossus.
In the Rallidae the muscle is absent in Rallus but well
developed in Fulica. In Fulica the origin extends along all
but the anterior end of the dorsomedial edge of the mandibu-
lar ramus, just dorsal to the origin of M. intermandibularis.
The insertion is on the floor of the mouth and the base of the
Summary. The muscle is absent in Aramus, Balearica,
and Rallus but is well developed in Grus and even more so in
Fulica. Its absence in Aramus and Balearica may be func-
tionally correlated with an insertion of M. stylohyoideus
much farther anterior than in Grus. This correlation is not
apparent in the two rallids, even though the insertion of M.
stylohyoideus is usually anterior to that of Grus. This mus-
cle is apparently modified in association with specialized
feeding habits. The well-developed condition, at least in
Fulica, is probably associated with pressing the tongue
against the papillae in the roof of the mouth in order to
27. M. dermoglossus
This muscle is absent in Aramus.
Comparisons. In the Gruidae the muscle is present. In
Balearica and Grus it is a short, thin sheet arising from the
basihyal bone. In Balearica the origin is from the lateral
face of the middle of the bone but from the dorsolateral
corner of the anterior end in Grus. The insertion in both
cranes is on the wall of the pharynx, but in Balearica it
also merges with M. constrictor colli and is joined by the
small sheet of the posterior part of M. ceratoglossus in-
ferior, arising from the middle of the ceratohyal. Contrac-
tion of the muscle would draw the lateral pharyngeal walls
forward, perhaps during swallowing.
According to Fisher and Goodman the muscle arises from
the pharynx and inserts on the basihyal. Since the pharyn-
geal attachment is the more movable, the origin and inser-
tion should be reversed, as they are described above.
In the Rallidae the muscle is absent.
Summary. The muscle is present in Gruidae, but in
Aramus and Rallidae it is absent.
28a. M. ceratoglossus lateralis
Very elongate and somewhat rounded. Located on lateral
and dorsal aspects of hyoid apparatus, from middle of cornu
to base of entoglossum. Attaches to ceratohyal, loosely to
basihyal, to M. stylohyoideus, to M. hypoglossus rectus, and
Posterior tip deep to posterior end of M. ceratoglossus
inferior and also to part of M. geniohyoideus. Most of mus-
cle lies deep to sheets of M. constrictor colli and M. inter-
mandibularis. Courses alongside M. hypoglossus obliquus and
M. hypoglossus rectus. Lies medial to insertion of M. stylo-
hvoideus. Located superficial to combined bellies of M.
thyroglossus and M. thyrohyoideus.
Origin. Arises fleshily from dorsal and lateral sur-
faces of anterior two-thirds of ceratohyal, and attaches
loosely to side of basihyal.
Insertion. Alongside M. hypoglossus obliquus belly
narrows into small tendon that continues anteriad to receive
portion of insertion of M. stylohyoideus, to attach to side
of M. hypoglossus rectus, and finally to merge with postero-
lateral region of entoglossum.
Action. One muscle bends tongue ventrolaterad, and
both together pull tongue downward.
Comparisons. In the Gruidae the muscle is superficial
to the posterior end of the posterior part of M. ceratoglossus
inferior, instead of deep to it as in Aramus. In Balearica
(and Aramus) the muscle arises from the dorsal and lateral
surfaces of the ceratohyal, but in Grus it arises from the
ventrolateral and dorsolateral surfaces. In both cranes (and
Aramus) the origin is from the anterior two-thirds of the
ceratohyal. The points of insertion in both gruids agree
with those of Aramus, but in Balearica (and Aramus) attach-
ment is by a tendon, and in Grus the muscle is fleshy
In the Rallidae the origin is from all but the ventral
surface of the full length of the ceratohyal bone (in Aramus
it arises from the dorsal and lateral surfaces of the anterior
two-thirds). In both rallids the small tendon begins at
about the middle of the belly and lies superficially on the
belly (in Aramus the tendon arises much farther forward, at
the anterior end of the belly). The insertion in both ral-
lids is essentially the same as in Aramus. In Fulica (and
Aramus) the inserting tendon receives part of the insertion
of M. stylohyoideus, but no such connection exists in Rallus.
Summary. Aramus differs from the rallids but resembles
the gruids in having a smaller area of origin and a shorter
tendon of insertion. However, Grus is unique among the genera
examined in having the insertion entirely fleshy.
28b. M. ceratoolossus inferior
Rather short band of muscle. Lies against ventral side
of hyoid musculature between posterior ends of mandibular
rami. Attaches to ceratohyal and to connective tissue in
The single slip in Aramus corresponds to the posterior
part in Grus, but the lateral and medial parts found in that
crane are lacking in the limpkin.
Muscle lies entirely deep to M. constrictor colli, and
posterior end also deep to M. geniohyoideus. Lies
superficial to M. ceratoqlossus lateralis on ceratohyal, and
belly lies superficial to M. thyroqlossus and M. thyrohyoideus.
Origin. Arises fleshily from ventral surface of cerato-
hyal, beneath M. geniohyoideus, from line of origin about as
long as width of muscle.
Insertion. Inserts in ventral mid-line, deep to area of
overlap of, and on connective tissue that forms insertion of,
M. constrictor colli and M. intermandibularis.
Action. May act to raise or protract hyoid apparatus,
cnmp~rrinnn. In the Gruidae, alearica agrees with
Aramnia in having the muscle represented by only the posterior
part, which is a band-like sheet. In Grus the muscle in-
cludes lateral and medial parts, and the posterior part is
more elongate and rounded. In rus both the lateral and
medial parts arise from the anterior end of the ceratohyal,
and the lateral part inserts on H. hvyoclossus rectua and on
the ventrolateral corner of the entoglossum, while the medial
part inserts on the middle of the basihyal. In Balearica
the sole (posterior) part arises from the entire surface of
the posterior one-third of the ceratohyal (in Aramus it arises
from a line about the width of the muscle), but in Grus the
corresponding origin is apparently much smaller. The inser-
tion of the posterior part in Balearica (and Aramus) is on
connective tissue in the ventral mid-line, but in Grus it is
on fascia over the junction of the basihyal and urohyal.
In the Rallidae the muscle is somewhat thicker in Fulica
than in Rallus (or Aramus). Points of attachment agree in
the rails and the limpkin.
Summary. The muscle differs only in thickness and ex-
tent of origin in the genera other than Grus, but in that
crane it includes two additional parts. The one part common
to all genera inserts in Grus in an entirely different loca-
tion from that of Balearica and the non-gruids. In Aramus,
Balearica, and the two rallids the muscle apparently func-
tions in raising the hyoid apparatus and perhaps in protract-
ing it, but in Grus the only apparent function is to adduct
the cornua of the hyoid.
29. M. hypoglossus rectus
Small, triangular muscle with attenuate anterior end.
Closely fused with opposite member in mid-line, and two mus-
cles have common tendon anteriorly. Occupies ventral face
of posterior end of entoglossum and median strip along ven-
tral surface of tongue. Attaches to entoglossum and to M.
Right and left muscles loosely connected across mid-
line. Completely deep to M. intermandibularis. Posterior
end adjacent to insertions of M. stylohyoideus and M.
Origin. Arises fleshily from general face of posterior
end of entoglossum, and to lesser extent, from inserting ten-
don of M. ceratoglossus lateralis.
Insertion. Right and left muscles have common insertion,
by narrow and strap-like tendon that extends along ventral
mid-line of tongue and attaches onto ventral side of anterior
portion of entoglossum.
Action. Causes tongue to curve downward.
Comparisons. In the Gruidae the muscle has fewer fleshy
fibers and more extensive tendons that in Aramus. In
Balearica (and Aramus) the main origin comes from the ento-
glossum, with a lesser origin from M. ceratoglossus lateralis,
but in Grus it arises mainly from the lateral part of M.
ceratoglossus inferior, which is lacking in Balearica (and
Aramus). In Grus the inserting tendon connects to M. genio-
glossus, which is also absent in Balearica (and Aramus).
The length of the inserting tendon varies with the length of
the tongue in the two cranes and the limpkin.
In the Rallidae the muscle differs from that of Aramus
in being slightly longer and narrower, with closer connection
to the inserting tendon of M. ceratoglossus lateralis. The
actual size of the belly is similar in both rallids in spite
of differences in the length of the tongue, but the tendon
is longer in Rallus. In Fulica only, the paired bellies do
not contact across the mid-line.
Summary. The pattern of the muscle is rather constant
in all genera studied, even though the length and shape of
the tongue vary considerably. Differences in the length of
the tongue are reflected in differences in the length of the
tendon of insertion. In Grus the muscle connects to two mus-
cles not present in the other genera.
30. M. hypoglossus obliquus
small, triangular muscle with lateral and ventral faces
at right angles to each other. Located on lateral and ven-
tral faces of anterior end of basihyal. Attaches to basi-
hyal and to entoglossum.
Right and left muscles loosely fused across mid-line.
Entirely deep to M. intermandibularis. Lies just medial to
anterior portion of M. ceratoglossus lateralis, ventromedial
to insertion of M. stylohyoideus. and just posterior to M.
Origin. Arises fleshily from lateral and medial faces
of anterior half of basihyal.
Insertion. Attaches fleshily to ventral and lateral
edges of posterior end of entoglossum, adjacent to posterior
edges origin of M. hypoglossus rectus.
Action. One muscle pulls tongue ventrolaterad, but both
muscles together depress distal portions of tongue.
Comparisons. In the Gruidae the muscle in Balearica is
thinner than in Grus (or Aramus), but it lies along the full
length of the ventral side of the basihyal instead of only
the anterior two-thirds as in Grus (or the anterior half as
in Aramus). In Grus the muscle is deep to the anterior ten-
don of the lateral part of M. ceratoglossus inferior and M.
genioglossus, and lies medial and superficial to the medial
part of M. ceratoglossus inferior; none of these muscles are
present in Balearica (or Aramus). The origin is more exten-
sive in Balearica than in Grus (or Aramus). Grus is unique
in having some tendinous components to the origin. In
Balearica (and Aramns) the insertion is on the ventral and
lateral edges of the posterior end of the entoglossum, but
in Grus the insertion is narrower, on only the ventrolateral
corner of the entoglossum. In Balearica only, the insertion
is partly on the medial side of the inserting tendon of M.
In the Rallidae the muscle is larger in Rallus than in
Fulica (or Aramus), but the shortened basihyal in the coot
makes comparison difficult. In Rallus the muscle occupies
the full length of the basihyal, but in Fulica it does not
cover the posterior end (in Aramus it covers only the ante-
rior end). The rallids differ from Aramus in having the mus-
cle attach to the medial side of the inserting tendon of M.
ceratoqlossus lateralisy this attachment is stronger in
Summary. The size and attachments of the muscle are
varied among the genera studied, and there seems to be no good
correlation with the length of the tongue. The muscle is
longest in Balearica and Rallus, but the tongue is short in
the former and long in the latter. The muscle is shortest
in Aramus, which has the longest tongue, and Fulica, which
has a short tongue. However, the two genera with the shortest
tongues, Balearica and Pulica, both have close connection of
the muscle to the tendon of M. ceratoglossus lateralis along-
side it. Such connection is very weak or lacking in the
other three genera, all of which have long tongues. This
muscle is certainly more subject to specialization than is
M. hypoglossus rectus.
31. M. thyroqlossus
32. M. thyrohyoideus
Long and somewhat rounded, composed of two inseparable
muscles, lateral M. thyrohyoideus and medial M. thyroglossus.
Very narrow, entirely separate accessory slip of former muscle
lies lateral to main belly. Located in ventral region of
pharynx, between hyoid apparatus and larynx. Attaches to
larynx, to wall of pharynx, to basihyal, to entoglossum, to
urohyal, and to ceratohyal.
Muscles on each side loosely connected across mid-line.
Posterior half partly deep to M. constrictor colli, M. inter-
mandibularis, and posterior part of M. ceratoglossus inferior;
anterior portion partly deep to M. ceratoglossus lateralis and
Origin. Main belly arises fleshily from lateral and
ventral regions of anterolateral portion of cricoid cartilage,
adjacent to lateral edges of M. thyroarytenoideus and M.
constrictor glottidis. Small portion originates from ventro-
lateral wall of pharynx, posterior to attachment to cricoid,
more or less continuous with portion of insertion of M.
tracheohyoideus in same area. Small accessory part of M.
thyrohyoideus arises separately from ventrolateral wall of
Insertion. Belly passes dorsal to basihyal, where
small fasciculi partially separate from main belly. One
fasciculus inserts on dorsolateral edge of basihyal about 2 mm
anterior to posterior end of bone. Other fasciculi remain
partially joined and insert fleshily on all of dorsal sur-
face of anterior third of basihyal and on entire posteroven-
tral edge of entoglossum. Separate accessory part of M.
thyrohyoideus inserts on junction of urohyal, basihyal, and
Action. Muscles on one side reflect tongue dorsolat-
erad. Both sides together raise distal portions of tongue,
retract hyoid apparatus, and protract larynx.
comparison. In the Gruidae the main origin is from the
posterior edge of the cricoid cartilage (in AramraL it arises
from the anterolateral portion). The cranes differ from
ran a=s in having the accessory part arise partly from the cri-
coid. In nl-iar.n (and Aramus) the muscle Partially divides
into fasciculi in the region dorsal to the basihyal, but it
remains as a compact mass in Grus. In Ralearica (and Aramus)
the muscle inserts on the dorsal surface of the basihyal but
inserts on the lateral surface in Gurs. In Baleari.c~ (and
Aramus), but not in G-1s, a small fasciculus parts from the
main muscle to insert on the posterior region of the basihyal.
In both cranes the accessory part fuses with the main muscle
instead of inserting separately as in Aramus.
In the Rallidae the two muscles under discussion differ
from those of Aramus in being separate and in lacking the
accessory part, In both rallids M. thyroglossus is wide
posteriorly and narrow anteriorly, but in Fulica the change
from wide to narrow is more abrupt. Sometimes in Rallus
(and always in Aramus the right and left Mm. thyroglossi are
loosely connected across the mid-line and lie superficial to
the medial edges of Mm. thvrohvoidei. In Fulica the two Mm.
thyroglossi are closely connected across the mid-line and lie
superficial to all but the posterolateral portions of Mm.
thyrohoidei. In both rallids M. thyroglossus arises mainly
from the posterior region of the cricoid (in Aramus it arises
from the anteroventral edge), and M. thyrohyoideus arises
from the ventrolateral region of the full length of the larynx
(from the anterolateral region in Aramus). In both rallids
M. thyroqlossus is short, inserting on the junction of the
basihyal, ceratohyal, and urohyal bones (in Aramus the main
muscle is farther anterior, but the above insertion is simi-
lar to that of the accessory part of M. thyrohoideus). In
Rallus M. thyrohyoideus inserts on the dorsal face of the
anterior portion of the basihyal (corresponds to the main
insertion of the combined muscle in Aramus), but in Fulica
this insertion is on most of the dorsal face of the basihyal.
Summary. The cranes and the limpkin are quite distinct
from the rallids in having the two muscles inseparably fused
and in having an accessory part. In the rallids the two
muscles are quite distinct from each other and are of dif-
ferent lengths. For minor variations, Aramus and Balearica
show almost as many points of agreement as do Balearica and
Grus. Aramus is unique in having these muscles insert on
the entoglossum. The two muscles are apparently good famil-
ial indicators, since some unique differences occur in each
33. M. tracheohyoideus
Narrow and very elongate dermo-osseus muscle, compact
in anterior and posterior regions but quite flattened in mid-
dle of belly. Forms part of wider sheet of muscle in poste-
rior region of neck. Located on ventrolateral side of full
length of neck, between trachea and skin. Attaches to larynx,
to trachea, to skin, to M. dermo-temporalis, and to furculum.
Deep to M. constrictor colli throughout at least ante-
rior two-thirds of neck. Adjacent to ventromedial edge of M.
tracheohyoideus and fused with same in posterior half of neck.
Origin. Arises fleshily from most ventral edge of fur-
culum, just lateral to mid-line. Originates as ventromedial
portion of common sheet formed by its fusion with M. dermo-
temporalis, but separates from ventral edge that muscle in
about middle of length of neck.
Insertion. Inserts on skin throughout posterior half of
length of belly, and attaches strongly to ventrolateral por-
tion of trachea near anterior end. Main insertion (which might
be considered as anterior origin) fleshy, mainly on postero-
lateral extent of cricoid, just posterior to insertion of
M. tracheohyoideus. Small slip diverges near anterior end
and further divides into smaller slips, some of which insert
on ventrolateral portion of most anterior extent of trachea,
and some of which attach to ventrolateral region of pharynx.
Latter slips more or less continuous with portion of origin
of M. thyrohyoideus in same area.
Action. Acts mainly with M. dermo-temporalis as flexor
of skin of neck, but may also retract trachea.
Comparisons. In the Gruidae the muscle in Balearica
(and Aramnsa extends from the furculum to the larynx, but in
Grus it occupies only the anterior third of the neck. In
Balearica (and Aramus) it arises fleshily from the furculum,
but in Grus it arises from the skin and from fascia between
the trachea and the vertebral column, about 14 cm from the
anterior end of the neck. In Balearica the muscle is con-
siderably thinner than in Aramus; the comparison is not
available for Grus. In Balearica the origin is from the full
width of the anterior face of the ventromedial portion of the
furculum (only from the ventromedial edge in Aramus), and the
posterior portion of the belly is indefinably fused with M.
dermo-temporalis (fused but still traceable in Aramus). In
Grus the muscle is not present in this portion of the neck.
In both cranes the muscle attaches to the anterior third of
the trachea (only to the anterior end in Aramus). In Balearica
(and Aramus) the main insertion is on the side of the poste-
rior edge of the cricoid, but in Grus it is on the ventral,
lateral, and dorsal surfaces of the posterior end of that
cartilage. The cranes agree with Aramus in having a small,
divergent slip form a portion of the insertion. This inser-
tion is compact in the gruids, on the wall of the pharynx
and the dorsal surface of the cricoid in Balearica, and on
the arytenoid in Grus (in Aramus the slip diverges into a
variable number of smaller ones that attach to the trachea
In the Rallidae the muscle in pallus agrees with that of
Aramus in dividing into a main portion and a small slip, but
in Fulica it is not divided. In both rallids the origin from
M. dermo-temporalis is like that of Aramus. In Rallus the
main origin comes from the sternoclavicular ligament and the
anteroventral corner of the keel of the sternum, ventral to
the bundles of M. dermo-temporalis. In Fulica it arises
mainly from the sternoclavicular ligament, dorsal to the
bundles of M. dermo-temporalis, but it soon crosses deep to
that muscle to assume the usual position along the ventro-
medial edge (in Aramus this origin is from the furculum).
In Rallus (and in Aramus) it remains fused with M. dermo-
temporalis through its posterior half, but in Fulica it is
fused only at the origin. In Rallus there is very little
attachment to the trachea anteriorly, but in Fulica (and
Aramus) it attaches for about the anterior third of its
length and has strong attachment to the dorsal side of the
trachea for a distance of about one cm. In Rallus (and
Aramus) the main portion inserts on the side of the poste-
rior end of the cricoid, and the small slip inserts on the
dorsal side of the larynx (and also on the pharynx in Aramus).
In Fulica there is no division, and the anterior end of the
muscle inserts as a single unit on the lateral and dorsal
sides of the posterior edge of the larynx.
Summary. In Grus the muscle is much shorter than in the
other genera, and the condition corresponds well with that
described by Fisher and Goodman (1955) for M. dermo-
temporalis in this crane. The reduction indicates a general
decrease in the movability of the cervical skin in Grus.
Variations occur between the members of the Gruidae and the
Rallidae in both posterior and anterior attachments. Aramus
is unique in having the most anterior portion of the inser-
tion divided into several small slips.
34. M. tracheolaryngeus superior
35. M. tracheolarynqeus inferior
single, elongate band of muscle, wide and thin in ante-
rior portion and more compactly narrow in posterior three-
fourths. Posterior extent divided into two slips. Thinner
portion covers ventral surfaces of larynx and anterior 2.5 cm
of trachea. Narrower portion continues from that point along
side of trachea to syrinx.
Fisher and Goodman (1955) found this muscle in two parts,
superior and inferior, which they described as separate mus-
At anterior end medial edges of right and left sheets
nearly in contact at mid-line. Lies deep to M. constrictor
colli and M. tracheohyoideus throughout most of length of
neck. Posteriorly, two slips pass on either side of inser-
tion of M. sternotrachealis.
Origin. Since this muscle does not attach to bone, and
is attached to movable structures at both ends, it is not
possible to designate a trenchant origin or insertion. It
seems most reasonable to regard both the laryngeal and
bronchial attachments as origins and the entire intervening
tracheal attachment as the insertion: that interpretation is
Anterior origin (listed as insertion of M. tracheolaryn-
geus superior in Fisher and Goodman, 1955, and origin of M.
tracheo-lateralis by Miskimen, 1951) arises from full length
and most of width of cricoid cartilage of larynx. Posterior
origin (comparable to insertion of M. tracheolaryngeus infe-
rior of Fisher and Goodman, and to insertion of M. tracheo-
lateralis in Miskimen) arises partly from most anterior
syringeal cartilage. From this point muscle immediately di-
vides into two slips that rejoin at another portion of origin,
just anterior to insertion of M. sternotrachealis; one slip
may give off tiny fasciculus to previous muscle.
Insertion. Wider anterior end attaches loosely to most
of ventral surface of trachea, but soon narrows and moves
laterad to insert loosely on narrow area along side of re-
mainder of length of trachea.
Action. Shortens trachea by drawing together cartilag-
inous rings but probably also retracts larynx and protracts
syrinx and bronchus.
Comparisons. The condition of the muscle in the limpkin
is closely approached in some passerines, according to
Miskimen's descriptions. However, she gives the laryngeal
attachment as the origin and states that the muscle divides
at its attachment to the anterior end of the syrinx to form
Mm. broncho-trachealis anticus and posticus, which insert on
the anterior end of the bronchus. The latter two seem to
represent separate muscles that are equivalent to the two
slips of the posterior end of M. tracheolaryngeus in Aramus.
In the Gruidae the muscle in Balearica agrees with the
single condition in Aramus, but in Grus it is divided into
superior and inferior parts, both of variable length. The
inferior part in Grus is narrower and much longer than the
corresponding portion in Balearica (or Aramus) because of the
extra length of the coiled trachea. The anterior origin in
Balearica and Grus is restricted to the medial portion of the
ventral edge of the cricoid (in Aramus it arises from most of
the ventral surface and the full width of the posterior edge
of the cartilage). In Balearica the posterior origin is by
a single tendinous band that extends anteriorly about half-
way to the insertion of M. sternotrachealis (as previously
noted by Beddard, 1898). In Grus this tendon is very short
(in Aramus the muscle arises, essentially fleshily, from the
syrinx by two heads that eventually fuse). In Balearica (and
Aramus) the anterior portion of the muscle is wide and at-
tached to the ventral surface of the trachea, but in Grus
this portion is narrower and apparently attached mainly at
the posterior end of the superior part. In the two cranes
the muscle receives the insertion of M. sternotrachealis,
but in Aramus the muscle divides and passes on either side
of the insertion of M. sternotrachealis.
In the Rallidae the muscle is somewhat larger than in
Aramus. In Fulica alone, it is very highly developed, form-
ing a continuous sheet from the dorsal to the ventral mid-
line in the anterior and posterior portions of the trachea.
There is even some overlap of the muscles from the two sides
on the dorsal surface of the posterior portion of the tra-
chea, and the muscle extends farther anteriorly on the side
of the trachea than in Rallus (or Aramus). In all three
specimens of Rallus the muscle on the left side divides poste-
riorly into three branches. The first of these continues
posteriad to become the posterior origin, the second becomes
the left M. sternotrachealis, and the third passes across
the ventral surface of the trachea to emerge with the right
M. sternotrachealis. The third branch is lacking on the
right side in Rallus and is absent on both sides in Fulica,
although in the latter genus the muscles on the two sides
are in contact by a thin ventral sheet (in Aramus there is no
contact between the muscles of the two sides, little or no
contribution to M. sternotrachealis, and on each side the mus-
cle divides into two heads, both of which continue to the
posterior origin). In both rallids the anterior origin is
from a smaller and more posterior portion of the ventral
surface of the cricoid than in Aramus. The posterior origin
is fleshy in both rallids (as in Aramus), but in Fulica it
is much wider. The insertion on the trachea is generally
weaker in Rallus than in Fulica (or Aramus).
Summary. This muscle is somewhat variable among the
three families and has intrafamilial differences in the
Gruidae and Rallidae. Aramus agrees with the rallids in
having a fleshy posterior origin, compared with the tendinous
one in the gruids. In the rallids the muscle gives off large
branches to form M. sternotrachealis, but in the non-rallids
there is little or no contribution to that muscle. Balearica
is similar to Fulica in the high degree of development of the
muscle, but it is considerably greater in the latter genus.
Unique specializations include the divided posterior end in
Aramus, the complete separation into two distinct muscles in
Grus, and the remarkable asymmetry in Rallus.
36. M. sternotrachealis
Small rounded muscle, about 1.5 mm in diameter and
about 30 mm long. Located in lateral region of space ante-
rior to heart. Connects trachea to rib cage, and also at-
taches to M. obliquus abdominis externus, to M. scalenus and
to Mm. intercostales externi.
Proximal end deep to anterior edge of M. obliquus ab-
dominis externus. Distal end contacts M. tracheolaryngeus.
Proximal end lies superficial to a small posterodorsal por-
tion of deep part of M. sternocoracoideus.
Origin. Arises by wide aponeurosis from ventral centi-
meter of last cervical rib and from upper third of first
sternal rib. Attaches also to portions of 1. scalenus, M.
obliquus abdominis externus, and most anterior of Mm. inter-
costales externi. Aponeurosis narrows abruptly, becomes
fleshy, and soon changes into rounded belly.
Insertion. Attaches to side of posterior end of tra-
chea, between the two slips of M. tracheolaryngeus, just
posterior to their point of origin.
Action. Retracts trachea, lengthening it and decreas-
ing tension on syrinx (see Miskimen, 1951).
Comparisons. In the Gruidae the muscle in Balearica
originates, less extensively than in Aramus, from the angle
between the sternal and vertebral parts of the first true
rib, but in Grus the origin is from the sternocoracoidal
process of the sternum. These two locations of the origin
in the gruids were described by Beddard (1898). In both
cranes the muscle inserts directly on M. tracheolaryngeus
(inserts between the two slips of that muscle in Aramus).
In the Rallidae the origin resembles that of Aramus,
but is somewhat more extensive on the left side. In both
rallids the muscle inserts as a branch of M. tracheolaryngeus
(see the description of that muscle). In Rallus the right
muscle divides and contributes to M. tracheolaryngeus on
both sides, but the left muscle is unbranched in Rallus, and
both sides are unbranched in Fulica (in Aramus both sides are
unbranched and have little connection to M. tracheolaryngeus).
In both rallids the insertion of the muscle on the right
side is slightly posterior to the left insertion (in Aramus
the insertions are symmetrical).
Summary. In Aramus the muscle has very little connection
to M. tracheolaryngeus, but there is more in the Gruidae, and
in the Rallidae the two muscles are continuous with each
other. Grus is distinct from Balearica and the non-gruids in
having the origin from the sternum. The rallids are unique
in having both the origin and the insertion asymmetrical.
37. M. thyroarytenoideus
Small and flattened triangular muscle. Located on pos-
terolateral portion of larynx. Attaches to cricoid and to
Anterolateral edge adjacent to portion of origin of M.
thyrohyoideus arising from larynx. Posterolateral corner of
belly ventral to insertion of portion of small slip of M.
tracheohyoideus. Superficial, in dorsal view of larynx, to
M. constrictor glottidis.
Origin. Arises fleshily from posterior edge of cricoid
and dorsal side of posterolateral portion of lateral cricoid.
Insertion. Inserts fleshily on lateral edge of aryten-
Action. Opens glottis by moving arytenoid laterad.
Summary. The pattern of this muscle is the same in all
the genera studied in the three families.
38. M. constrictor qlottidis
Small and flattened, triangular muscle. Located on
dorsal side of larynx. Attaches to medial and lateral cri-
coids and to arytenoid.
Deep in dorsal view to M. thyroarytenoideus. Antero-
lateral edge adjacent to portion of origin of M. thyrohy-
oideus arising from larynx.
Origin. Originates fleshily from medial cricoid and
from dorsal surface of lateral flange on posterior half of
Insertion. On medial side of anterior half of lateral
Action. Closes glottis.
Comparisons. In the Gruidae the portion of the origin
from the lateral flange of the arytenoid is lacking in Grus
(as in Aramus), and the insertion is on connective tissue
around the anterior end of the arytenoid as well as on the
lateral cricoid (only on the lateral cricoid in Aramus).
This muscle was not found in Balearica, but the region
was not well preserved. The muscle is presumably present in
a reduced condition in this crane.
In the Rallidae the muscle in Rallus arises only from
the medial cricoid (arises also from the lateral flange of
the arytenoid in Aramus), but in Fulica it arises from the
medial cricoid and all along the side of the arytenoid car-
tilage. In Rallus the insertion is partly on connective tis-
sue around the anterior end of the arytenoid and partly on
the middle of the dorsomedial rim of the lateral cricoid
cartilage (in Aramus the insertion is only on the anterior
half of the lateral cricoid). In Fulica the insertion is
only on the lateral cricoid, but it occupies the entire dor-
Summary. Some rearrangement of the muscle has apparently
occurred in the evolution of the various genera. In Aramus,
and even more so in Fulica, the origin is moved anteriorly
onto the arytenoid. This attachment may be associated with a
need for more effective closing of the glottis in these two
underwater feeders. The muscle is essentially the same in
Grus and Rallus. Its presence is uncertain in Balearica.
Muscles of the Orbit
39. M. orbicularis palpebrarum
This muscle sheet is greatly reduced in the limpkin, and
is represented by only a few fibers on the inner side of the
lower lid. Its action (Shufeldt, 1890) is to close the eye,
mainly by raising the lower lid.
Comparisons. In the Gruidae it is apparently better
developed in Grus, arising from the anterior end of the jugal
bar and from the lacrimal bone and inserting mainly on the
lower eyelid. Only a few fibers of the muscle could be found
in Balearica, perhaps partly because of inadequate preserva-
tion in the region.
In the Rallidae no trace of the muscle was found.
Summary. The muscle exists as a recognizable sheet only
in Grus. It is much reduced in the other genera and is
probably absent in Rallidae.
40. M. elevator palpebrae
Very thin, wide sheet with few contractile fibers.
Covers upper side of eyeball. Attaches to roof of orbit and
to upper lid.
Encloses dorsal side of eyeball and eye muscles on that
Origin. Arises from inner edge of roof of orbit.
Insertion. Inserts into inner side of upper lid.
Action. Helps open eye by raising upper lid.
Summary. The muscle is the same in the limpkin, the
two cranes, and both rallids.
41. M. depressor palpebrae
Very thin, wide sheet with few contractile fibers.
Covers posteroventral region of eyeball. Attaches to inter-
orbital septum and to lower lid.
Superficial to M. rectus externus and M. rectus inferior.
Origin. Arises from ventral region of interorbital
septum, along narrow line just ventral to origins of M. rec-
tus inferior and M. rectus externus.
Insertion. Fuses to inner side of most of length of
Action. Opens sye by depressing lower lid.
Comparisons. In the Gruidae it arises from a very small
area just dorsal to the anterior end of the origin of the M.
protractor quadratus (the area of origin is very elongate in
Aramus and located just ventral to the origins of the lower
two rectus muscles).
In the Rallidae the muscle in Rallus is essentially like
that of Aramus, but in Fulica the line of origin is longer
and extends farther anteriorly.
Summary. The origin of the muscle in the two cranes is
small and located posteroventral to the elongate origin of
Aramus and the two rallids. Otherwise the muscle is similar
in all three families.
42. M. quadratus nictitantis
Thin, somewhat rhomboidal sheet with bundles converging
to smaller ventral edge. Visibly separate in upper region
into smaller anterior and larger posterior portions. Lies
over most of dorsal region of inner side of eyeball. At-
taches to sclera and to tendon of M. pyramidalis nictitantis.
In medial view of eye, lies partly deep to M. obliquus
superior, to M. rectus superior, and to M. rectus externus.
Fascia of ventral edge encloses small tendon of M. pyramidalis
Origin. Arises from thin longitudinal line extending
about one-third of circumference of eyeball, along its dorso-
Insertion. Inserts as fascial pulley enclosing tendon
of M. pyramidalis nictitantis.
Action. Maintains tension on enclosed tendon, to hold
it away from optic nerve and to allow it to move nictitating
Comparisons. In the Gruidae the muscle in Balearica
(as in Aramus) is large, with a partial division in the up-
per region, but in Grus the belly is considerably smaller
and apparently has no division.
In the Rallidae Rallus has a smaller belly with less of
it covered by M. rectus superior than in Fulica (or Aramus),
and the pulley is likewise smaller. In Rallus the pulley
enclosing the tendon of M. pyramidalis nictitantis is shorter
than in Fulica (or Aramus).
Summary. This muscle is generally similar in all the
genera examined, but some minor variations seem to have arisen
as adaptations. The belly is larger in Aramus, Balearica,
and Fulica than in Grus and Rallus, implying more use of the
nictitating membrane in the first three than in the latter
two. This may be related to the more aquatic habitat, at
least of Aramus and Fulica. A definite partial division in
the belly is present in each genus except Grus, but the sep-
aration is quite small in Rallus. The significance of this
is not clear, but it seems to correlate well with the differ-
ences in size.
43. M. pyramidalis nictitantis
Composed of small, flat, and elongately triangular belly
with very slender, rounded tendon leading from apex. Lo-
cated on anteroventral region of inner side of eyeball, just
anterodorsal to optic nerve. Tendon extends around to pos-
teroventral region of lateral surface of eyeball. Attaches
to sclera, to M. quadratus nictitantis, and to nictitating
In medial view partly deep to M. obliquus inferior, to
M. rectus inferior, and to M. rectus internus. Inserting
tendon passes through pulley formed by free end of M.
Origin. Arises from narrow longitudinal line of sclera
at anteroventral edge of inner side of eyeball.
Insertion. Small tendon leaves apex of belly, passes
through pulley of M. quadratus nictitantis, and passes to
ventrolateral region of eyeball to insert on posteroventral
corner of nictitating membrane.
Action. Pulls nictitating membrane posteriad, covering
Comparisons. In the Gruidae the muscle is similar to
that of Aramus but it seems to be slightly smaller in Grus
than in Balearica (and Aramus).
In the Rallidae the muscle in Rallus is larger than in
Fulica (and considerably larger than in Aramus), and a smaller
portion is enclosed by the pulley of M. quadratus nictitantis
than in Fulica (or Aramus).
Summary. The muscle varies only in size among the genera
studied, but the differences occur within the Gruidae as well
as within the Rallidae. The larger size of this muscle in
Rallus is contrasted with the smaller size of M. quadratus
nictitantis in that genus. It would seem, on the basis of
the present muscle, that Rallus has more use of the nictitat-
ing membrane, but the smaller size of the former muscle indi-
cates that such an interpretation is oversimplified.
44. M. obliquus superior
Flat and fan-shaped. Lies on anterodorsal surface of
inner side of eyeball. Attaches to interorbital septum and
to sclera of eyeball.
Deep to M. elevator palpebrae superioris, and postero-
lateral edge deep to M. rectus superior. Superficial to
anterodorsal edge of M. quadratus nictitantis.
Origin. Arises fleshily from elongately oval scar at
extreme anterodorsal extent of interorbital septum.
Insertion. Inserts by short but wide aponeurosis, onto
sclera of posterodorsal region of inner side of eyeball,
mostly between origin of M. quadratus nictitantis and inser-
tion of M. rectus superior.
Action. Rolls eyeball inward in anterodorsal direction.
Comparisons. In the Gruidae the proximal end and its
area of origin are large (relatively small in Aramus). In
Balearica (and Aramus) the insertion is wider than in Grus.
In the Rallidae the elongate area of origin in Rallus
is oriented nearly vertically but is more nearly horizontal
in Fulica (and Aramus). In Rallus the belly is fleshy to
the point of insertion, but there is a short aponeurosis in
Fulica (and a more extensive one in Aramus).
Summary. Only very slight differences exist in this
muscle among the genera, but some occur within the Gruidae
and Rallidae. The two cranes differ from Aramus and the two
rallids in having a considerably larger area of origin for
45. M. obliquus inferior
Narrow and partially rounded band of muscle. Located
on anteroventral portion of inner side of eyeball. Attaches
to interorbital septum and to sclera.
Superficial to anterior edge of M. pyramidalis nicti-
tantis and to anterior edge of M. rectus internus.
Origin. Arises fleshily from rounded scar in middle of
extreme anterior edge of interorbital septum.
Insertion. Attaches by short aponeurosis to sclera in
anteroventral region of inner side of eyeball.
Action. Rotates eyeball in anteroventral direction.
Comparisons. In the Gruidae the muscle is widely flat-
tened (narrow and rounded in Aramus). In Balearica (and
Aramus) it originates from the middle of the anterior edge of
the interorbital septum. Fisher and Goodman (1955) show this
origin (p. 11) as arising with the rectus muscles from a
scar just anteroventral to the optic foramen. Apparently the
drawing is incorrect in this point, since they state (p. 37)
that the eye muscles follow the usual vertebrate pattern;
furthermore, skeletons examined of Grus grus, G. canadensis,
Anthropoides paradisea, and A. virgo all plainly show a scar
in the location described above for Balearica and Aramus.
In the Rallidae the area of origin in Rallus (nd Aramus)
is rounded, but it is elongate in Fulica and closer to the
origin of the other oblique muscles.
Summary. This muscle is similar in all genera dis-
sected, except perhaps Grus (see above).
46. M. rectus superior
Flat and elongately triangular muscle. Lies over pos-
terodorsal aspect of inner side of eyeball. Attaches to
interorbital septum and to sclera.
Deep to M. elevator palpebrae superioris. Superficial
to posterolateral corner of M. obliquus superior and to pot-
tion of M. quadratus nictitantis.
Origin. Originates fleshily from oval scar on postero-
dorsal edge of interorbital septum.
Insertion. Belly changes to thin aponeurosis in upper
third and inserts on narrow line on sclera in dorsal region
of inner side of eyeball, along dorsal edge of insertion of
M. obliquus superior.
Action. Rotates eyeball anterodorsad.
Comparisons. In the Gruidae the muscle is essentially
the same as in the limpkin.
In the Rallidae the muscle in Rallus differs from that
of Aramus only in arising from an area slightly closer to the
optic foramen. The origin in Fulica is located intermediate
to that of Rallus and Aramus.
Summary. The muscle is quite similar in all genera
47. M. rectus inferior
Small band of muscle. Located on posteroventral region
of inner side of eyeball. Attaches to interorbital septum
and to sclera.
Superficial to ventral edge of M. pyramidalis nictitantis.
Origin. Arises fleshily from oval scar on interorbital
septum, just anteroventral to optic nerve.
Insertion. Becomes aponeurotic in ventral 3 mm and in-
serts on anteroventral region of inner side of eyeball.
Action. Rotates eyeball anteroventrad.
Comparisons. In the Gruidae the area of origin is pos-
teroventral to the optic foramen (anteroventral to that fora-
men in Aramus).
In the Rallidae the muscle differs from that of the
limpkin only in being slightly more rounded.
Summary. The two cranes differ slightly from Aramus and
the rallids in the location of the origin, but the rails dif-
fer from Aramus and the cranes in having the belly slightly
more rounded. Other features are closely similar in all three
48. M. rectus externus
Short, moderately thick band of muscle. Lies on postero-
ventral region of inner side of eyeball. Attaches to wall of
orbit and to sclera.
Superficial to portion of tendon of M. pyramidalis
Origin. Arises fleshily from rounded scar, which par-
tially surrounds foramen for sixth cranial nerve, on wall of
orbit just posteroventral to optic foramen.
Insertion. Attaches by thin, short aponeurosis to sclera
of posterior region of inner side of eyeball.
Action. Rotates eyeball posteriad.
Comparisons. In the Gruidae the area of origin in
Balearica is posterior to the optic foramen, but in Grus it
is posterodorsal to the foramen (posteroventral to it in
Aramus). The muscle is otherwise similar in the two cranes
and the limpkin.
In the Rallidae the area of origin is wide and adjacent
to the posterior edge of the optic foramen (narrower in
Aramus and posteroventral to the optic foramen).