Applied sonoanatomy of the posterior triangle of the neck
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 Material Information
Title: Applied sonoanatomy of the posterior triangle of the neck
Series Title: International Journal of Shoulder Surgery
Physical Description: Journal Article
Language: English
Creator: Ihnatsenka, Barys ( Author, Primary )
Boezaart, Andre P. ( Author, Secondary )
Publisher: Medknow Publications
Publication Date: 2010
 Notes
Abstract: The posterior triangle of the neck is an area of the body frequently visited by regional anesthesiologists, acute and chronic pain physicians, surgeons of all disciplines, and diagnosticians. It houses the entire brachial plexus from the roots to the divisions, the scalene muscles, the cervical sympathetic ganglions, the major blood vessels to and from the brain, the neuroforamina and various other structures of more or less importance to these physicians. Ultrasound (US) offers a handy visual tool for these structures to be viewed in real time and, therefore, its popularity and the need to understand it. We will discuss pertinent clinical anatomy of the neck and offer a basic visual explanation of the often-difficult two-dimensional (2-D) images seen with US.
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Full Text
ISSN 0973 - 6042


International Journal of

Shoulder Surgery


Volume 4 Issue 3 Jul-Sep 2010


Contents


> Shoulder sonography: Diagnostic and interventional utility

> Ultrasound: Basic understanding and learning the language

> Applied sonoanatomy of the posterior triangle of the neck

> Cytogenetic analysis of the pathology of frozen shoulder

> Axillary artery pseudoaneurysm after plate osteosynthesis for a clavicle nonunion:
A case report and literature review

> Irreducible anterior and posterior dislocation of the shoulder due to incarceration
of the biceps tendon


Online full text at
www.internationalshoulderjournal.org


Published by M wPublications










Review



Applied sonoanatomy of the posterior

triangle of the neck

Barys Ihnatsenka1, Andre Pierre Boezaart1,2





The posterior triangle of the neck is an area of the body frequently visited by regional
anesthesiologists, acute and chronic pain physicians, surgeons of all disciplines, and
diagnosticians. It houses the entire brachial plexus from the roots to the divisions, the scalene
muscles, the cervical sympathetic ganglions, the major blood vessels to and from the brain,
the neuroforamina and various other structures of more or less importance to these physicians.
Ultrasound (US) offers a handy visual tool for these structures to be viewed in real time and,
therefore, its popularity and the need to understand it. We will discuss pertinent clinical anatomy
of the neck and offer a basic visual explanation of the often-difficult two-dimensional (2-D)
images seen with US.

Key words: Brachial plexus block, cervical plexus block, neck, sonoanatomy, stellate ganglion
block, supraclavicular area, thoracic outlet, ultrasound


The posterior triangle of the neck is an area of the body
frequently visited by regional anesthesiologists, acute and
chronic pain physicians, surgeons of all disciplines and
diagnosticians. It houses the entire brachial plexus (BP), from
the roots to the divisions, the scalene muscles, the cervical
sympathetic ganglions, the major blood vessels to and from
the brain, the neuroforamina and various other structures of
more or less importance to these physicians. Ultrasound (US)
offers a handy visual tool for these structures to be viewed
in real time and, therefore, its popularity and the need to
understand it. There are several components that are important
for successful US image acquisition and understanding: (1)
basic knowledge of "US appearance" of different tissues and
anatomical structures, (2) knowledge of how adjustments to
US machine settings and the use of different transducers may
affect the US image to our best advantage, (3) knowledge of
how transducer manipulation may help the ultrasonographer
to get the best picture and how to understand US picture
changes related to probe manipulation and (4) knowledge of
clinical three-dimensional (3D) anatomy of the scanned area.


Website:
www intemationalshoulderjournal org
DOI:
10 4103/0973-6042 76963
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BUBS~fij*|


The previous article ("Ultrasound: Basic Understanding
and Learning the Language") is focused on the first three
components. The purpose of this paper is to cover the last
component. We will discuss pertinent clinical anatomy of the
neck and offer a basic visual explanation of the often-difficult
two-dimensional (2-D) images seen with US. The authors
suggest that the accompanying article be studied before reading
this paper. At the end of this article, we provide an example
of a systemic approach to the use of US where we combine
ideas from two papers.

Clinical anatomy of the posterior triangle of
the neck
Surface landmarks"'6
Knowledge of surface landmarks is useful for the initial
probe placement on the skin or as a reference tool if the
ultrasonographer "gets lost in the US image" and needs to regain
his or her bearing.
* The posterior border of the posterior triangle of the
neck is the trapezius muscle, its anterior border is the
sternocleidomastoid muscle and its inferior border is the
clavicle.


63 International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 +







Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck

* The level of the cricoid cartilage corresponds to the level
of the 6th cervical vertebra (C6). This line is perpendicular
to the spine and this must be kept in mind with flexion
and extension of the neck.
* The external jugular vein commonly crosses the posterior
border of the sternocleidomastoid muscle at the level
where the BP exits between the anterior and the middle
scalene muscles. This is commonly known as "Winnie's
point."15-71
* The level of the upper margin of the thyroid cartilage
corresponds to C4. The level of the chin with the head in
neutral position also corresponds to C4.
* Dividing the distance between the C4 level and the tip of
the mastoid process into thirds will indicate the positions
of C2 and C3 on the line connecting the transverse process
of C6 (carotid tubercle) and mastoid process if the neck
is in the neutral position.
* The midpoint of the distance between the proximal and
the distal attachments of the sternocleidomastoid muscle
on its posterior border corresponds to the exit point of
the superficial cervical plexus (SCP).
* The lateral border of the first rib is usually located on the
line drawn through a point 3 cm lateral to the insertion
point of the clavicular head of the sternocleidomastoid
muscle. Cupola of the lung is logically located medial to
the medial border of the rib.
* The midpoint of the clavicle usually corresponds to the
position of the BP beneath it, although the position of the
clavicle changes significantly with changes in the shoulder
position.

Cervical vertebrae, first rib and clavicle
Bones are not as well visualized on US as with fluoroscopy, but
they are still visible (especially outer contour and, especially,
if they are not too deep) and could be very helpful landmarks.

Even though it is not related to sonoanatomy it is important
to know the 3D anatomy of the bones because they serve as
protective barriers for some vital vascular and neural structures
whenever needles are inserted in that area. Therefore, we
dedicate some extra attention to the skeletal anatomy of the
neck area. Aligning the target structure (nerve plexus for
example) on the US screen in a way that other vulnerable
structures vertebrall artery or neuraxium for example) are
"shielded" by bone adds extra safety to the procedure in case the
ultrasonographer loses the tip of the needle from the US view.

There are seven cervical vertebrae. The first (Ci) does not have
atypical spinous process, and the C2-C7 spinous processes are
often split at the end.

The laminae of the cervical vertebrae is visible in the
posterolateral sagital US plane and can be used for guiding
a needle for placement on the bone to initiate a paramedial
approach for the cervical intralaminar epidural.

+ International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 64


The articular processes of the cervical vertebrae create articular
"columns" with an uninterrupted bony wall that can also be seen
in axial and sagital posterolateral views (personal observation).
It is important to notice that from C3 to C6, the lateral border
of the articular column is about 5-7 mm more lateral than
the vertebral artery. That makes posterior approaches to the
cervical or BP, such as Pipa's or Boezaart's approaches, safer in
regard to inadvertent injury to the vertebral artery.8'*91 Changing
needle trajectory from the true posterior-anterior, which
gives "bony wall" protection of the articular column, to any
other trajectory with needle direction from posterolateral to
anteromedial makes the vertebral artery more vulnerable unless
constant direct visualization of the needle and artery is used.

Facet joints are visible on US and can be used for facet joint
injection. The "waist" of the particular process of each vertebra
is also visible and is a surrogate marker for medial branch nerve
block for diagnosis or treatment of facet joint arthropathy.

The transverse processes of the cervical vertebrae are
different from other transverse processes.' 41 A typical cervical
transverse process is directed downward (caudad) and outward
anteriorlyy) and is shaped like a trough. Each of the transverse
processes has an anterior tubercle and posterior tubercle,
except the transverse process of C7, which has no or only a
rudimentary anterior tubercle.

If the cervical spine is viewed from the side (lateral axial view),
you should note that the transverse processes are not exactly
underneath each other if the probe is moved down or up along
the straight line because of the curvature of the neck (personal
observation). When viewing the vertebrae from the side, it can
be seen that the posterior tubercle is usually lower than the
anterior tubercle of the upper cervical vertebrae (C2-C5). The
lower vertebrae, especially C7, are the other way round. To
visualize both tubercles, mild probe rotation may be needed.

The anterior tubercle of the C6 transverse process is prominent
(carotid or Chassaignac's tubercle).['1 It is an important landmark.

The C7 has the most distinguished shape. The C7 transverse
process is usually positioned slightly more posterior and caudat
than the C6 transverse process and has a big posterior tubercle
and rudimentary or absent anterior tubercle when viewed in
the axial view, which gives it a "thumb up" appearance on the
US [Figures 1 and 2].

Determining both the C6 and the C7 transverse processes
improves the specificity in determining the correct level of
the cervical spine being viewed. To determine it at the higher
level, one can slowly slide the probe cephalad while counting
transverse processes from the known reference points of C7
and C6.

If using bony landmarks to determine the level of the
cervical spinal nerve, it should be noted that the BP roots are







Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck


Figure 1: Axial cut through the neck at the C6 level. Fascias, muscles,
bones, vessels and nerves: (1) sternocleidomastoid muscle, (2) anterior
scalene muscle, (3) longus colli muscle, (4) middle scalene muscle, (5)
posterior scalene muscle, (6) elevator scapulae muscle, (7) vertebral
artery, (8) recurrent laryngeal nerve, (9) vagus, (10) phrenic nerve, (11)
sympathetic ganglion, (12) brachial plexus, (13) branches of superficial
cervical plexus (supraclavicular nerves), (14) carotid sheath

situated between the anterior and the posterior tubercles of
the corresponding transverse processes (C6 root at the C6
transverse process). The C8 root is, however, situated below
the C7 transverse process and the Ti root originates from below
the first rib (below the Ti transverse process).

All seven cervical vertebrae have transverse foraminae in
their transverse processes.J'1 The vertebral artery enters the C6
transverse foramen in go90% of the people. In 10% of the people,
it enters the transverse foramen of C5 or C4.[1o] The reason for
the presence of a transverse foramen in the transverse process
of the C7 vertebra is not fully understood.

The neuroforaminae are posterior and cephalad to the
transverse process. It is important to study the position of
the neuroforaminas because they could theoretically be the
inadvertent entry point inside the spinal canal for the long
block needles when the classic Winnie interscalene block (ISB)
is performed." 1-13

The classical Winnie's recommendation for needle direction
during ISB is "perpendicular to all planes with slight caudal
angulation." Caudad needle angulation theoretically was
supposed to be safer than the horizontal direction. This was
based on the fact that transverse processes also have some
caudal angulation and the assumption that if the nerve root
is missed (no paresthesia or motor response with needle
stimulation) and the needle is being advanced medially, it
would eventually hit the "floor" of the transverse process and
would less likely enter the spinal canal via the neuroforamina.
In reality, because the transverse foramen creates a "hole" in the


Figure 2: Schematic illustration of lateral axial ultrasound neck image
generation at the C7 vertebral level. (1) Middle scalene muscle, (2)
anterior scalene muscle, (3) posterior tubercle of C7, (4) vertebral
artery, (5) derivates of the C5 roots, (6) C6 root, (7) C7 root, (8)
rudimentary anterior tubercle of the C7 transverse process. Note the
difference of the shape of the transverse processes of C6 [Figure 1]
and C7 [Figure 2]

"floor" of the transverse process, needle passage from a cephalad
direction may not be interrupted by expected bone, and the
needle will pass into the spinal canal via the neuroforamina
below (personal observation on the skeleton).

Despite the above reasoning, some caudal angulation during
needle advancement is probably safer than true horizontal
needle direction (possible needle advancement straight into
the neuroforamina at the level of entry). Theoretically based
on analysis of the cervical spine anatomy, the most dangerous
needle direction during classic Winnie's ISB in regard to
inadvertent entry into the spinal canal would be medial,
posterior and cephalad. The distance from the skin to the spinal
canal could be very small (about 2 cm) in some patients,[51 and
even short needles may not protect from this catastrophic
complication.

Posterior approaches to brachial and cervical plexuses,1 '91
or so called "lateral" approach,l'4] are much safer in regard to
inadvertent entry into the spinal canal compared with the
classic Winnie approach. Visualization of the needle and
the targeted structure with US makes posterior and lateral
techniques even safer.

The anterior surface of the vertebral body and the intervertebral
disks can also be visualized with US during an anterior sagital
scan.

The first rib is angulated downward and anterior and it can be
readily traced with US (personal observation). Slightly tilting
and rotating the probe can maintain the vision of the first rib

65 International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 +







Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck

in the true axial view when tracing it from the head of the rib
toward the sternum. Bony structures of the cervical spine could
be used as a "back stop" for inadvertent injury to the vertebral
artery and neuraxium by the block needle. The first rib could
be used as a "back stop" for inadvertent injury to the pleura
and lung during supraclavicular BP block.

The clavicle is an important bony structure that is fixed at the
sternum and is mobile laterally when changing the position of
the shoulder. This mobility could be used for obtaining more
favorable scanning or needling window by moving the patient's
shoulder in the most optimal direction. This simple trick is
frequently overlooked by practitioners (personal observation).

Muscles and fascia
Visualizing and differentiating the muscle and fascial planes
is important for intramuscular injection of botulinum toxin
or is more commonly needed as important landmarks and
reference points in our search for nerves during neural
blockade. Commonly, small nerves are not seen with US and
compartment blocks are performed. Therefore, knowledge of
the sonoanatomy of muscle and fascial planes is very essential
[Figure 1].

A hyperechoic rim surrounding the muscle represents fascia.
Fascia is important because it influences the extent of LA
spread.

(Additional comment to Figure 1) Note that the transverse
process of C6 vertebrae has anterior and posterior tubercle.
Figure 2 demonstrates an axial section of the neck at the C7
level, and you can see that the transverse process of C7 has no
anterior tubercle and thus has a "thumb up" appearance on US.

The concept of BP sheath and plexus anesthesia is another
example of the importance of fascia in regional anesthesia.[15-171
The "plexus sheath" remains a controversial concept
and is looked at not as a specific tubular fascial structure
surrounding the neurovascular bundle but rather as a fascial
compartment formed by the fascia of the surrounding muscles.
The pattern of spread of LA around the nerve structures is
readily observed during live US-guided nerve blocks. When
observing the spread of LA during neural blockade using live
US, you should remember that while you see only a 2D picture,
in reality, the "pool" of LA has a 3D shape. Moving the US probe
around may help to estimate the spread of LA more accurately.

The SCP cutaneouss innervation) is situated outside the
prevertebral fascia (13 on Figure 1) of the neck and most of the
nerves exit posterior of the midpoint of the sternocleidomastoid
muscle.[1] It originates from the deep cervical plexus (DCP),
which originates from the anterior rami of the C1-C4 spinal
nerves.

The DCP is located below the prevertebral fascia in the
paravertebral space at the level of C1-C4 and innervates

+ International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 66


the deep neck muscles via corresponding short branches
and diaphragm via the phrenic nerve.J'1 The BP originates
from the anterior rami of C5-Tispinal nerves and is also
located below the deep fascia in the paravertebral space, but
more caudally.J'1 Accidentally penetrating the prevertebral
fascia during intended SCP block for cutaneous anesthesia or
analgesia may unintentionally lead to a partial DCP block with
resulting possible phrenic nerve paralysis or partial BP block and
weakness of the arm (personal observation). The intentional
blockade of the DCP in turn will also cause blockade of the
SCP.151

Also note that the 11th cranial nerve (the accessory nerve) is
situated above the deep fascia in proximity to the SCP. This
nerve could also be blocked during attempted SCP block, but
is unlikely during a DCP block.[-51s

Fascial planes are seen best during US-guided "hydro dissection."

Adipose and soft connective tissue and lymph nodes are
commonly seen between fascial planes and can be easily
visualized by US to estimate their involvement in the
pathologic processes (degree of lymphadenopathy for example).
Occasionally, small deep lymph nodes may confuse the
ultrasonographer because they may look like nerves (round
hypoanechoic structures).

Deep muscles of the neck
Longus colli, longus capitis and anterior, middle and posterior
scalene muscles [Figure 3].


I

~fld.It
4*


r
p1


Figure 3: Deep cervical muscles. (1) Longus capitis muscle, (2)
superior cervical sympathetic ganglion, (3) rectus capitis muscle,
(4) middle scalene, (5) longus colli, (6) posterior scalene muscle, (7)
anterior scalene muscle, (8) middle cervical sympathetic ganglion, (9)
inferior cervical and upper thoracic sympathetic ganglions, (10) thoracic
duct, (11) phrenic nerve, (12) suprascapular nerve, (13) brachial plexus









The longus colli muscle is situated on the anterior surface of the
vertebral bodies and is covered by a deep layer of prevertebral
fascia. It is approximately 1 cm wide. Injecting LA into the
muscle compartment or subfascially at the level of C6 will
cause a sympathetic chain and stellate ganglion block because
all these structures are inside of this fascial compartment. At
a higher level (C2 or C3) the superior cervical sympathetic
ganglion or DCP may be blocked by injecting the LA into the
longus capitis muscle compartment deep to the deep fascia
layer [Figure 3].

There are three scalene muscles: the anterior, middle and
posterior scalene muscles. Note the attachments for these
muscles [Figure 3] and the relationship of these attachments
to the subclavian artery, BP and DCP. The anterior scalene
muscle attaches proximally to the anterior tubercles of the
transverse processes of C3-C6 and distally to the first rib in
front of the subclavian artery, and the middle scalene muscle
attaches proximally to the posterior tubercles of the transverse
processes of C2-C7 and distally to the first rib posterior to
the subclavian artery. The posterior scalene muscle attaches
proximally to the posterior tubercles of the transverse
processes of C4-C6 and distally to the external border of the
second rib [Figure 3].

The spindle shape of the anterior scalene muscle, which is of
special note, can be visualized as the US probe slides up the
neck (personal observation). It is at its thickest at the level
of the cricoid cartilage, but gets thinner as it tracts cephalad
and caudad, where it is thin again as it attaches to the first rib.
The anterior and middle scalene muscles create the groove
or space for the BP and subclavian artery. Injecting LA in this
space will provide BP blockade. The anterior scalene does not
extend higher than the level of C4 or C3. Above that level,
the longus capitis and middle scalene create the groove or
paravertebral space for the DCP. It may, therefore, be possible
to block the DCP with a single injection at or above the C4
level. Moreover, with a typical C6 level interscalene approach
to the BP, substantial cephalad spread is possible along the
middle scalene muscle if a large volume of LA is used, which
explains the consistent block of the SCP and phrenic nerve
with the classic ISB.l'8'19

The phrenic nerve courses downward on the anterior surface
of the anterior scalene muscle from the lateral border of
the anterior scalene muscle to its medial border behind the
subclavian vein into the mediastinum. The phrenic nerve is
occasionally visible with US between the sternocleidomastoid
and anterior scalene.

As illustrated in Figure 3, the anterior scalene is relatively
thin in the middle part of the neck at approximately the level
of C5. The phrenic nerve is therefore close to the BP at this
point. Anterior spread of LA to the phrenic nerve over the
thin anterior scalene muscle at this level could thus be another
mechanism of phrenic nerve block during ISB.


Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck

To avoid unintentional phrenic nerve blockade during ISB, the
BP should be approached as low as possible in the interscalene
grove where the phrenic nerve is situated most anterior, further
away from the BP. Also, the BP could be approached from the
posterior to avoid penetration of the anterior scalene muscle
and smaller volumes of LA could be used.

If interscalene BP block is performed lower in the interscalene
groove, cephalad spread of LA may also be less prominent,
possibly resulting in reduced blockade of the cutaneous nerves
of the SCP (supraclavicular nerves responsible for cutaneous
innervation of the "shoulder cape").

The anterior scalene muscle is at its thickest at the level of C6
or C7, and therefore is most suitable for intramuscular injection
of paralyzing agents such as botulinum toxin for the possible
treatment of neurogenic thoracic outlet syndrome.[2o]

The posterior neck muscles, the erectors of the cervical spine,
are commonly very tender after any injury or due to tension.
When performing posterior approaches to the brachial or cervical
plexuses, a muscle-sparing needle trajectory to decrease neck
pain should be selected. It is easy to achieve this through the
space between the trapezius and the elevator scapula muscles for
cervical paravertebral block of the brachial or cervical plexuses.121]

Superficial muscles
The sternocleidomastoid muscle forms the anterior border of
the posterior triangle of the neck. It could be used to rapidly
navigate the level of an US scan of the neck; the posterior border
of this muscle covers the interscalene groove at Winnie's point,
although at the C3/C4 level its anterior border is close to the
transverse process line. The position of the head, especially
rotation, affects the relationship of this muscle in regard to
deep structures. The omohyoid muscle is another superficial
muscle that could be seen with US where it was overlying the
BP at the base of the neck.

Thyroid, Esophagus
These structures are primarily used as important landmarks and
need to be recognized to avoid inadvertent damage to them
during neural blockades.

Although not strictly situated in the posterior triangle of the
neck, the thyroid gland is easily identifiable and forms a handy
landmark for ultrasonography of the neck. The cricoid cartilage
is positioned close to the C6 vertebral level and the lower lobe
of the thyroid is therefore close to the level of C7-Ti and the
upper lobe is close to the level of C5-C6. By sliding the US
probe cephalad along the thyroid gland keeping the area that
is just lateral to the great vessels in view, the carotid tubercle
of C6 can be seen when the thyroid is about to disappear from
view [Figure 4].

The recurrent laryngeal nerves are situated between the
trachea and the thyroid gland. Because the pretracheal fascia

67 International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 +







Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck


Figure 4: Lateral axial ultrasound neck image at the upper pole of thyroid (C6 vertebral level). (1) Middle scalene, (2) C5 nerve root, (3) C6
nerve root, (4) anterior scalene, (5) sternocleidomastoid, (6) carotid artery, (7) thyroid, (8) longus colli, (9) posterior tubercle of C6, (10) anterior
tubercle of C6 (carotid tubercle)


envelops all visceral structures in the anterior neck and
provides an extra protection barrier for it, unintentional
recurrent nerve blockade occurs most likely at a point where
the nerve loops around the subclavian artery on the right
side (17 at Figure 4), or it happened due to vagus block more
proximally.

The esophagus can be injured during cervical sympathetic block.
Asking a patient to swallow helps to pinpoint the esophagus
by observing its movement when in doubt. Remember that
the esophagus is frequently positioned more to the left of the
trachea rather than just behind it.

Blood vessels
Blood vessels [Figure 5] serve as important anatomical
landmarks and also should be actively looked for and avoided
during needle advancement. The color Doppler function must
be used to distinguish nerve roots from arteries because they
may look very similar. This is especially true for vertebral artery
and thyrocervical trunk at and below the C7 level.

The great vessels: common carotid artery (CCA) and internal
jugular vein (IJV), are easy and consistent reference points
during neck US scanning. The carotid sheath (14 in Figure 1)
envelops the CCA, the IJV and the Vagus nerve.[1] The IJV
is collapsible with slight pressure of the US probe or when
the patient's head and torso are elevated. To best visualize
the IJV and other veins, the Trendelenberg position could be
used or the patient can perform a Valsava maneuver. Valves
are frequently visible in the subclavian or innominate veins,
which helps to distinguish veins from arteries when transmitted
pulsations are present.

The CCA courses from anterior and medial to more posterior
and lateral as it ascends cephalad. At the level of C4, the CCA
divides into the external and internal carotid arteries, and the
bifurcation could be used as a C3-C4-level landmark.'41

The more cephalad portion of the carotid artery is closer to
the nerve roots than lower down in the neck. Therefore, if the

* International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 68


Figure 5: Neck blood vessels. (1) Middle scalene muscle, (2) anterior
scalene muscle, (3) dorsal scapular nerve, (4) transverse cervical
artery, (5) phrenic nerve, (6) brachial plexus, (7) dorsal scapular artery,
(8) suprascapular artery, (9) thyrocervical artery, (10) lung, (11) inferior
cervical sympathetic ganglion, (12) longus colli muscle, (13) vertebral
artery, (14) vagus, (15) inferior thyroid artery, (16) middle cervical
sympathetic ganglion, (17) recurrent laryngeal nerve

nerve roots and carotid artery are close to each other on US, it
probably indicates a relatively high scanning level.

The vertebral artery (13 in Figure 5) arises from the
posterosuperior aspect of the subclavian artery, and in go90%
of the people, it enters the transverse foramen of the C6
vertebra as it courses cephalad.1o] The vertebral artery is
exposed and could be injured during deep cervical block,
cervical sympathetic block and BP block, especially if the last
two are performed caudad of the C6 transverse process (at
and above the C6 transverse process, the vertebral artery is
at least partially protected by bone when it traverses via the
transverse foramen). It can be seen below the C6 transverse
process slightly anterior to the nerve roots and also between any
other transverse processes above C6 in a longitudinal and even
in an axial view at any higher level in the neck. As mentioned









earlier, the posterior approaches to BP or to DCP are safer in
regard to inadvertent injury to the vertebral artery because
the vertebral artery is situated medial to the lateral border of
the articular column that serves as a protective wall of bones
when the needle is advanced from the posterior.

The thyrocervical trunk (9 in Figure 5) is more lateral than
the vertebral artery. Both vessels can be seen in an axial view
at the base of the neck.

The dorsal scapular and, less frequently, the transverse cervical
and suprascapular arteries course posterolaterally through the
BP. These arteries can be seen during US-assisted supraclavicular
BP block [Figure 6].

During cervical sympathetic block, the superior thyroid artery,
a branch of the carotid artery, and the inferior thyroid artery,
a branch of the thyrocervical trunk, commonly traverse across
the needle trajectory and can be seen when color Doppler is
used.

Use of color Doppler or power Doppler is advisable to identify
small arteries and veins around the intervertebral foramina
when a US-guided neuroforaminal epidural or proximal root
injection is performed. These are important blood vessels that
supply the spinal cord.

On the left side of the lower lateral part of the neck, it is
sometimes possible to identify the thoracic lymph duct as it
loops from inside out and joins the great veins (lo in Figure 3).

Lung cupola
US is helpful in visualizing the lung cupola and may aid in
avoiding lung and pleural injury. The lower trunk of the
BP courses across the lung cupola. The inferior sympathetic
ganglion is situated very close to the lung cupola as well.
Pneumothorax is a possible complication after any BP blocks
above the clavicle and after stellate ganglion block. US use
should decrease the risk of pneumothorax and can also be used
in the timely diagnosis of pneumothorax.

Neural structures
Visualization of neural structures in the neck could be used
for the diagnosis of several nerve entrapment syndromes, but


Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck

is more commonly used for US-guided neural blockade.

The echotexture of the proximal nerves is different from the
echotexture of the distal nerves.Es'7'A Roots of the DCP - the
anterior rami of the Ci-C4 spinal nerves, and the BP - the
anterior rami of the C5-T1 spinal nerves, are hypoanechoic
and look similar to blood vessels. (Color Doppler can easily
distinguish these from blood vessels.) This appearance
is not fully understood but could be because of the high
ratio of neural tissue (axon-rich fascicles that are anechoic)
to nonneural connective tissue (stroma of the nerves).
Hyperechoic appearance of the distal peripheral nerves is
probably explained by an increased amount of nonneural
perifascicular connective tissue that is almost absent in roots
that are densely "packed" with axon-rich fascicles.'l9 The
amount of neural tissue logically decreases as more and more
proximal nerve branches take off the spinal nerve as the nerve
passes distally. Another explanation could be that spinal nerves
as they exit the spine are surrounded by dura and, compared
with the peripheral nerves, this dura has not yet migrated
into the roots of the BP as it appears more distally to form
the septae in the trunks or perineurium of the fascicles in the
peripheral nerves.22'23]

Contrary to the roots or trunks and divisions, the terminal
branches of the brachial and cervical plexuses in the neck, such
as dorsal scapula nerve, suprascapular nerve, elevator scapula
nerve, long thoracic nerve, supraclavicular nerves and phrenic
nerve, are difficult to identify with US. Their visibility depends
on their size, the echocontrast of the surrounding tissues and the
quality of the US machine used (and sometimes the experience
of the ultrasonographer). The proximity of known structures
can provide an "educated guess" to where these nerves should
be situated if selective blocks of these nerves are needed.

Proximal BP sonoanatomy (neck area)
Five roots of the BP form the three trunks. E'61 Each trunk
has two divisions that eventually rearrange into three cords
and several distal terminal branches. This most common
representation occurs only in about 65% of the people. There
are approximately 39 other variations.15-7'191

Figure 2 depicts the spatial orientation of the BP and offers
an explanation of the typical lateral axial US scan through


Figure 6: Supraclavicular ultrasound scan demonstrating the dorsal scapular artery. (1) First rib, (2) lung, (3) subclavian artery, (4) dorsal scapular
artery, (5) middle scalene muscle, (6) anterior scalene muscle, (7) brachial plexus


69 International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 +







Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck

it at the C7 level. See also Figure 7 for the actual US image
of this level.

The BP is located between the anterior and the middle scalene
muscles and courses posterolaterally to the subclavian artery
over the cupola of the lung and the first rib, under the clavicle.
Some aberrant BP roots occasionally perforate the anterior
scalene muscle proximally and then rejoin the plexus more
distally.

Dural sleeves surround the roots of the BP, yet US technology
has not developed far enough to allow us to visualize these
dural sleeves. In general, therefore, we cannot reliably tell where
the roots become trunks and whether the trunks split into the
divisions and so on. All proximal blocks should therefore be
regarded as root-level blocks or extradural blocks.E22'231

With the US, we can differentiate the root level (C5 versus C6,
for example) when tracing a particular root or its derivatives
back to the corresponding transverse process (Figure 7 for C7
root and Figure 4 for C6 root), but it is more difficult to do so
when we only see five to nine round, hypoanechoic structures
one above the other more distal in the interscalene space
[Figure 8 for example]. We can usually make an "educated
guess" of the identity of the particular "round" neural structure.
As depicted in Figure 2, the more caudal in the neck we scan,
the more nerves we see; the more proximal roots and their
derivatives are situated more superficially and more distal roots


are situated deeper on the US picture (one may miss them if US
depth is set too shallow). Because of the unpredictable pattern
of division of the roots, it is inaccurate to simply count them
down assuming that the first most superficial round structure is
C5 and the next is C6 and so on. We can confirm our assumption
regarding neural structure identity by the appropriate motor
response with nerve stimulation or by tracing each structure
proximally to the level of the corresponding transverse
processes where they initially originate [Figures 4, 7, and 9].
The last maneuver is more reliable.

The ability to differentiate the identity of the neural structures
in the neck with US is clinically significant for neural blockade.
With any high (C5/C6 cervical level) proximal approach to
BP block, there is a challenge to cover a wide anatomical space
to achieve a complete block of the entire BP (C5-Ti roots)
because those roots are spaced apart. The distance from C5 root
to Ti root could be about 7 cm.161 Figure 2 gives an insight to
that challenge if we look at the vertical distance from C5 to
C7 and imagine that we trying to cover that area with LA by
injecting it from the C5/C6 intervertebral level.

It is well known that with classic ISB that is usually performed
at the C6 level, the lower positioned C8 and Tiroots will be
missed up to 30-50% of the time using the normal volume
of LA. If one uses increased volumes of LA or performs the
block by using more than one needle position (moving it
to the area that is not covered by LA from first injection),


Figure 7: Lateral axial ultrasound neck image at the C7 level. (1) Posterior tubercle of the C7 transverse process, (2) rudimentary anterior tubercle
of the C7 transverse process, (3) C7 root, (4) middle scalene muscle, (5) anterior scalene muscle, (6) longus coli muscle, (7) sternocleidomastoid
muscle, (8) vertebral artery, (9) carotid artery, (10) brachial plexus (C5-C6 derivates)


Figure 8: Sagital supraclavicular ultrasound scan. (1) First rib, (2) lung, (3) subclavian artery, (4) middle scalene muscle, (5) omohyoid muscle,
(6) anterior scalene muscle, (7) brachial plexus


+ International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 70







Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck


Figure 9: Lateral axial ultrasound neck image at the C4 vertebral level. (1) C5 transverse process, (2) C4 root, (3) middle scalene muscle, (4)
anterior scalene/longus coli muscles, (5) sternocleidomastoid muscle, (6) carotid artery, (7) thyroid cartilage


a more complete block could be expected. Unfortunately,
when we use continuous block and infusion of LA, the limit
is 5-1o ml/h and, therefore, it is very important that the tip
of the catheter be positioned in the most favorable spot for
a particular surgery (C5/C6 root derivatives for shoulder and
upper arm surgery; C7 root derivatives for elbow surgery;
C8/Ti roots derivatives for wrist and hand surgery). US
guidance may be very helpful for this, especially for lower
root derivatives that are situated close to the lung cupola and
important vascular structures.

As seen in Figure 2, the C5/C6 root derivatives could be blocked
at the C6 vertebral level (classic Winnie approach for example)
or at the C7vertebrae level or even lower (supraclavicular
level for example). The question is if any difference exists
based on the point of the blockade. It is logical that if one
chooses to block C5/C6 roots and their derivatives very low
(below the C7 vertebra), there is a higher chance that some
proximal derivatives, such as the suprascapular nerve, could
be missed if that particular nerve had already branched off. As
was mentioned earlier, blocking the C5/C6 root derivatives
at the C6 vertebra level usually provides consistent block of
the supraclavicular nerves (C3-C4 derivatives responsible for
shoulder cape cutaneous anesthesia) and suprascapular nerve.
Unfortunately, phrenic nerve is also inadvertently blocked due
to some cephalad and anterior spread of LA.

It seems logical that a block of the same C5/C6 derivatives at
the C7 level [Figures 2 and 7] may be the most advantages for
optimal analgesic coverage and fewer side-effects. Some studies
confirm this notion but more research is needed.E241

C7 root derivatives could also be blocked at different levels:
the C7 transverse process level or lower. Blocking it at the C7
transverse process seems to be quite optimal in regard to the
risk of lung and vascular injury vertebrall artery and subclavian
artery and its branches). There is no data regarding comparison
of that approach with a block that is performed more distally
(supraclavicular continuous block for example). Factors
unrelated to the quality of the block or risk of immediate
complications may determine the choice of one technique over
another. Theoretically, geriatric patients with less-spacious


and less-compliant plexus sheath in the area between the rib
and the clavicle could be more vulnerable to the risk of high
BP sheath compartment pressure secondary to continuous
infusion via the supraclavicular plexus catheter. Authors of
this article believe that this is not the case with more spacious
paravertebral space during continuous cervical paravertebral
block with the tip of the catheter at the C7 root. This notion
needs more research.

Distal BP sonoanatomy (supraclavicular area)
Tracing the BP with US from the neck more distally, the
ultrasonographer gets into the supraclavicular area.

Occasionally, for proximal plexus blocks, it is easier to start US
examination from the supraclavicular area where the subclavian
artery serves as a consistent reliable US landmark and traces
the BP up proximally.

In the supraclavicular area (right above the clavicle), the BP
is at its trunk or divisions level (neural structures are still
hypoanechoic). The trunks (superior, middle and inferior)
are usually vertically positioned one above the other at the
lateral side of the interscalene groove and medial border of
the first rib. At the lateral border of the first rib, the trunks
are usually divided into divisions, but there is a considerable
variability of the point of division and BP organization. In
general, the BP looks like a "bunch of grapes" located superior
and posterolateral to the artery.[251 The sheath-like structure is
commonly seen around the BP on US and a distinct "pop" is
felt and "seen" on penetration of this structure with the block
needle.

In the supraclavicular area, the derivatives of the C5, C6 and
C7 roots are situated superior, posterior and lateral to the
subclavian artery. Occasionally, but rarely, some of those nerves
are located superior and medial to the artery (artery splits
the BP into two parts, personal observation). The derivatives
of the C8 and Ti roots are consistently located in the corner
between the subclavian artery and the lung or the first rib.[251 If
the block of those nerves (C8, Ti roots derivatives) is important
for a particular procedure, the practitioner should manipulate
the US probe (see later) and obtain the image that shows the

71 International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 +







Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck

subclavian artery and the BP "sitting" on the first rib rather than
on the lung. When such an image is obtained, the so-called
"corner pocket" technique should be used when the needle is
advanced in plane with US beam into the corner between the
artery and the first rib.[261 In this approach, the first rib serves
as a "back stop" to prevent inadvertent pleura or lung injury
in case an ultrasonographer fails to accurately visualize the tip
of the needle. It is also important to understand that cupola
of the lung is medial and one should avoid medial deviation
of the needle at all cost. Ideally, the entire needle and the tip
should be clearly visualized during the procedure. Injection of
the LA in the "pocket corner" reliably blocks derivatives of the
lower roots that are commonly missed with more proximal
approaches, such as interscalene, and thus this variation of
supraclavicular block is optimal for distal arm and hand surgery.
With a high volume of LA injected into the "pocket corner,"
the entire arm, with the exception of the shoulder, will be
blocked. For faster block set up when single injection block
is performed, after initial injection of some of the LA in the
"corner pocket," the needle could be repositioned so that the
LA is deposited directly around the derivatives of the C5-C7
roots as well.1271

Occasionally, when the US probe is positioned in the
supraclavicular area posterior to the middle third of the clavicle,
the subclavian artery is visualized "sitting" on the lung rather
than on the first rib. Tilting the US probe as if you are trying to
sweep the US plane anteriorly (probe handle moves posterior)
is the most common trick that helps to "put the subclavian
artery on the rib." Attention should be paid to correct patient
position. When the patient's shoulder is moved up and
backward, the clavicle also moves up and backward, forcing the
ultrasonographer to place an US transducer too high and too
medial in the supraclavicular area where the subclavian artery
is still on the lung cupola medial to the first rib.128]

The complete BP blockade is common when the block is
performed below the C7, right above the proximal part of the
first rib slightly more lateral than a typical ISB but more medial
than atypical supraclavicular block. Figure 8 demonstrates the
US image of this spot. Winnie also described this point in his
subclaviann perivascular approach."1291 At this point, the entire
BP is bundled together and could be blocked with a small
volume of LA. At this area, attention should be paid to avoid
puncturing the lung cupola and the vertebral artery and again
US could be very valuable.

DCP (C1-C4)
The roots of C2, C3 and C4 (the root of Ci is a pure motor
nerve) need to be located in order to perform an US-guided
block of the DCP. Identification of these roots is based on the
identification of the corresponding transverse processes and
counting them up from the C7 and C6 transverse processes.
Injection of several milliliters of LA at each root or, as
mentioned earlier, a single injection at the C3 or C4 level of
a larger volume of LA are possible alternatives [Figure 9].[31o

+ International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 72


SCP
We can usually not see the SCP with US but we can see the
deep fascia and sternocleidomastoid muscle above it and can
"hydrodissect" the appropriate fascial plane with LA at the
classic landmark point (see earlier).

The phrenic nerve originates mostly from the C4 [Figure 3], but
the sometimes-present accessory phrenic nerve originates lower
from the C5 or even the C6.11' US-guided BP block may decrease
the risk of a phrenic nerve block by injecting the LA around
the BP, away from the phrenic nerve (avoiding LA "spill" medial
and superior to the subclavian artery during supraclavicular
block and performing a C5/C6 root derivative block at the
C7 transverse process level via a posterior approach). 11 This
area needs more research.

The sympathetic ganglions and chain are located deep to the
prevertebral layer of the deep fascia on the deep muscles
(longus colli and longus capitis) or right on the surface of that
fascia (between alar fascia and prevertebral fascia).[1] There
are three cervical ganglions: the superior cervical ganglion at
the C2 level, the middle cervical ganglion at the C5-C6 level
and the lower cervical ganglion at the C7 level [Figure 3]. US
visualization of the sympathetic structures is not consistent,
but they usually present as hyperechoic spindle-like structures
(personal observation). The low cervical ganglion and the upper
thoracic ganglion fuse to form the stellate ganglion, which is
typically located at the head of the first rib close to the dome
of the lung.

Preganglionic sympathetic fibers of the cervical sympathetic
chain come from the upper thoracic segments of the spinal cord
and the postganglionic grey rami communicantes innervate the
upper extremity and head probably by penetrating the deep
cervical musclesb1 before joining the BP or entering the cranium
along the blood vessels.

The sympathetic chain or ganglions could be blocked
intentionally for diagnosis and treatment of sympathetically
maintained pain from the arm, head or upper torso or for
other indications such as Reynolds syndrome, hyperhydrosis
and vascular headaches. To perform this block, LA can be
injected under the prevertebral fascia or right above the
fascia (between prevertebral and alar fascia) [33341 or into the
belly of the longus colli muscle13�1 at the level of C6 (several
techniques exist). If LA is injected into the muscle, the
longus colli muscle fascial compartment will allow cephalad
and caudad spread of LA beyond the injection point.
All these approaches obviate the need to perform an injection
in the area close to the lung cupola at the level of C7-Ti
due to reliable spread of LA along the fascial planes from
the C6-level injection. Injecting LA more cephalad (C4
level for example) could be theoretically more selective for
upper and middle cervical ganglions, which would be more
beneficial for sympathetic block of the cranium rather than
the arm.







Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck


Occasionally, sympathetic blocks that accompany the BP
block are more extensive and cover the unilateral sympathetic
innervations of the head, which presents as Homer's syndrome.
It is usually harmless and occurs secondary to extensive
spread of a relatively high volume of LA between the deep
muscles under the prevertebral fascia in the proximity of the
sympathetic chain.

Suprascapular nerve blockade is required for shoulder surgery.
It innervates the posterior shoulder capsule, acromio-clavicular
joint, coraco-clavicular and coraco-acromial ligaments, the
supraspinatus and infraspinatus muscles and the subacromial
space. The suprascapular nerve originates from the upper trunk
of the BP and is reliably blocked during proximal blocks, such
as typical cervical paravertebral block or ISB and, occasionally,
during supraclavicular blocks, if LA was deposited more
proximally along the upper trunk.

If the suprascapular nerve has not been blocked, or needs to be
selectively blocked for diagnostic or therapeutic reasons, it could
be blocked more distally, where it passes onto the posterior
surface of the scapula and US could be used for this block.331

Important cranial nerves such as the vagus, accessory,
hypoglossal, glossopharyngeal and facial nerves pass through
the neck and can be blocked during different procedures
intentionally or unintentionally. As mentioned before, it is
difficult to visualize these nerves with US at this level of
technological progress.

Use of the systemic approach versus pattern
recognition
To demonstrate the use of the systemic approach, two
supraclavicular ultrasound scans [Figure loa and b] and
underlying 3D anatomy are illustrated. Positioning the probe on
line A, just posterior to the clavicle in the coronal plane [Figure
loa] produces the familiar US picture for supraclavicular BP
block (pattern recognition for "pocket corner technique").

It is also possible to place the probe in a slightly different
position on line B [Figure iob]. The probe is now situated
more posterior and medial along the axis of the subclavian
artery and the first rib. This could be achieved by sliding the
probe in this direction or just rotating it clock wise. Tilting the
probe handle more anterior may also produce similar results
(image B instead of image A). The two images (A and B) may
look similar, especially if the depth of the scan is shallow (not
like on the illustration where the depth is optimal to see the
"step down" from the rib to the pleura).

In position B, however, the artery is situated directly on the
pleura of the lung and in position A it is situated on the first rib.

In some patients, due to anatomical variation, a picture similar
to Figure iob would be obtained initially where the subclavian
artery is situated on the pleura and not the first rib, even if


A US picture Drawina


11


Figure 10: Three-dimensional sonoanatomy of the supraclavicular
scans. (1) Subclavian artery, (2) brachial plexus, (3) first rib, (4)
pleura/lung

the probe was placed right behind the clavicle. In this case,
tilting the probe handle more posterior may "bring" the artery
on the first rib.

Incorrect patient positioning when the shoulders, and therefore
the clavicles, are moved too cephalad and backwards might
also cause the probe to be "forced" by clavicles into position B
rather than position A.

If one fails to recognize that instead of "text book" image
A we have image B, and attempts to perform the "corner
pocket" block technique in this situation, he or she may cause
a pneumothorax.

The ability to interpret the US image correctly, distinguish
the hyperechoic line of the rib from the similar-looking line
of the pleura, the knowledge of the applied 3D anatomy, in
this case the relationships between the clavicle, first rib, the
subclavian artery and the lung in the supraclavicular area and
the knowledge of how probe manipulation (tilt, rotation and
sliding) may help to obtain the correct structures alignment
could help to perform the most advantageous US-guided
injections and avoid complications.



1. Williams PL. Gray's Anatomy: The Anatomical Basis of Medicine
and Surgery. 38t' ed. New York: Churchill Livingstone; 1995.
2. Netter FH. Atlas of human anatomy. 4" ed. Philadelphia: Saunders
Elsevier; 2006. plates 18-21, 26-35, 71, 74-6, 129-31, 136.

73 International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 *








Ihnatsenka and Boezaart: Sonoanatomy of the posterior triangle of neck

3. Agur AM, Dalley AF, editors. Grant's Atlas of Anatomy. 11t ed.
Baltimore: Lippincott Williams and Wilkins; 2005. p. 721-91.
4. Rohen JW, Yokochi C, Liitjen-Drecoll. Color Atlas of Anatomy:
A Photographic Study of the Human Body. 5t" ed. Baltimore:
Lippincott Williams and Wilkins; 2002. p. 166-83.
5. Cousins MJ, Bridenbaugh PO, Carr DB, Horlocker TT. The
upper extremity: Somatic block, in Cousins and Bridenbaugh's
neural blockade in clinical anesthesia and pain medicine. 4t"1
ed. Philadelphia: Wolters Kluwer and Lippincott Williams and
Wilkins; 2009. p. 316-42,420-5.
6. Boezaart AP, Franco CD. Blocks above clavicle. Anesthesia and
Orthopaedic Surgery. New York: McGraw-Hill; 2006. p. 291-309.
7. Winnie AP. Interscalene brachial plexus block. Anesth Analg
1970;49:455-66.
8. Pippa P, Cominelli E, Marinelli C, Aito S. Brachial plexus block
using the posterior approach. Eur J Anaesth 1990;7:411-20.
9. Boezaart AP, Koorn R, Rosenquist RW. Paravertebral approach to
the brachial plexus: An anatomical improvement in technique.
Reg Anesth Pain Med 2003;28:241-4.
10. Matula C, Trattnig S, Tschabitscher M, Day JD, Koos WT. The
course of the prevertebral segment of the vertebral artery:
Anatomy and clinical significance. Surg Neurol 1997;48:125-31.
11. Benumof JL. Permanent loss of cervical spinal cord function
associated with interscalene block performed under general
anesthesia. Anesthesiology 2000;93:1541-4.
12. Sardesai AM, Patel R, Denny NM, Menon DK, Dixon AK,
Herrick MJ, et al. Interscalene brachial plexus block: Can the
risk of entering the spinal cord by reduced? A study of needle
angles in volunteers undergoing magnetic resonance imaging.
Anesthesiology 2006;105:9-13.
13. Borgeat A, Blumenthal S. Unintended destinations of local
anesthetics. In: Neal JM, Rathmell JP, editors. Complications in
Regional Anesthesia and Pain Medicine. Philadelphia: Saunders
Elsevier; 2007. p. 157-63.
14. Borgeat A, Ekatodramis G. Anesthesia for shoulder surgery. Best
Pract Res Clin Anaesthesiol 2002;16:211-25.
15. Thompson GE, Rorie DK. Functional anatomy of the brachial
plexus sheath. Anesthesiology 1983;59:117-22.
16. Partridge BL, Katz J, Benireschke K. Functional anatomy
of the brachial plexus sheath: Implications for anesthesia.
Anesthesiology 1987;66:743-7.
17. Cornish PB, Leaper C. The sheath of the brachial plexus: Fact
or fiction? Anesthesiology 2006;105:563-5.
18. Urmey WF, Talts KH, Sharrok NE. 100% incidence of
hemidiaphragmatic paresis associated with interscalene brachial
plexus block as diagnosed by ultrasonography. Anesth Analg
1991;72:498-503.
19. Neal JM, Gerancher JC, Hebl JR, Ilfeld BM, McCartney CJ,
Franco DC, etal. Upper extremity regional anesthesia: Essentials
of our current understanding, 2008. Reg Anesth Pain Med
2009;34:134-70.


20. Boezaart AP, Haller A, Laduzenski S, Koyyalamudi V, Ihnatsenka
B, Wright T. Neurogenic thoracic outlet syndrome: A case report
and review of the literature. Int J Shoulder Surg 2010. [In Press].
21. Boezaart AP, de Beer JF, Nell ML. Early experience with
continuous cervical paravertebral block using a stimulating
catheter. Reg Anesth Pain Med 2003;28:406-13.
22. Boezaart AP. That which we call a rose by any other name would
smell as sweet - and its thorns would hurt as much. Reg Anesth
Pain Med 2009;1:3-7.
23. Boezaart AP, Tighe P. New trends in regional anesthesia for
shoulder surgery: Avoiding devastating complications. Int J
Shoulder Surg 2010. [In Press].
24. Renes S, Spoormans H, Gielen M, Retting H, Geffen G.
Hemidiaphragmatic paresis can be avoided in ultrasound-guided
supraclavicular brachial plexus block. Reg Anesth Pain Med
2009;34:595-9.
25. Burns DA, Filip P. Ultrasound Guided Regional Anesthesia and
Pain Medicine. Philadelphia: Wolters Kluwer and Lippincott
Williams and Wilkins; 2010. p. 40-58.
26. Shares LG, Brull R, Lai J, Chan V. Eight ball, corner pocket: The
optimal needle position for ultrasound-guided supraclavicular
block. Reg Anesth Pain Med 2007;32:94-5.
27. Chan VW, Perlas A, Rawson R, Odukoya 0. Ultrasound
guided supraclavicular brachial plexus block. Anesth Analg
2003;97:1514-7.
28. Perlas A, Lobo G, Lo N, Brull R, Chan VW, Karkhanis R.
Ultrasound guided supraclavicular block: Outcome of 510
consecutive cases. Reg Anesth Pain Med 2009;34:171-6.
29. Winnie AP, Collins VJ. The subclavian perivascular approach
of brachial plexus anesthesia. Anesthesiology 1964;25:353-63.
30. Boezaart AP, Nosovitch MA. Carotid endarterectomy using single
injection posterior cervical paravertebral block. Anesth Analg
2005;101:1885-6.
31. Renes S, Retting HC, Gielen MJ, Wilder-Smith OH, van Geffen
GJ. Ultrasound-guided low-dose interscalene brachial plexus
block reduces the incidence of hemidiaphragmatic paresis. Reg
Anesth Pain Med 2009;34:498-502.
32. Shibata Y, Fujiwara Y, Komatsu T. A new approach to ultrasound
guided stellate ganglion block. Anesth Analg 2007;105:550-1.
33. Gofeld M, Bhatia A, Abbas S, Ganapathy S, Johnson M.
Development and validation of a new technique for ultrasound-
guided stellate ganglion block. Reg Anesth Pain Med 2009;
34:475-9.
34. Peng P, Narouze S. Ultrasound guided interventional procedures
in pain medicine: Review of anatomy, sonoanatomy and
procedures. Part 1: Non-axial structures. Reg Anesth Pain Med
2009;34:458-74.


Source of Support: Nil, Conflict of Interest: None declared.


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possible articles in PubMed will be given.


+ International Journal of Shoulder Surgery - Jul-Sep 2010 / Vol 4 / Issue 3 74




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