Functional Anatomy and Action ( Publisher's URL )

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Functional Anatomy and Action
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Johnson, Joe B.
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
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Gainesville, Fla.


Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
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General Note:
"Date first printed August 1965. Date revised June 1989."
General Note:
"section 2 of 14 of 4HHSG01, which supersedes CO 201,"

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NAME_________________________________________________________________________________________ ADDRESS_____________________________________________________________________________________ CLUB_________________________________________________________________________________________ 4-H HORSE PROGRAM HORSE SCIENCE This educational material has been prepared for 4-H use by the Cooperative Extension Services of the U.S. Department of Agriculture and State Land-Grant Universities in cooperation with the National 4-H Council and the American Quarter Horse Association. Trade or brand names used in the publications are used only for the purpose of educational information. The information given herein is supplied with the understanding that no discrimination is intended and no endorsement of products or breeds of horses by the Federal Extension Service or State Cooperative Extension Services is implied, nor does it imply approval of products or breeds of horses to the exclusion of others which may also be suitable. This material was originally published by the National 4-H Council, 7100 Connecticut Avenue, Chevy Chase, Maryland 20815. Programs and educational materials of National 4-H Council are available to all persons regardless of race, color, sex, age, religion, national origin or handicap. Council is an equal opportunity employer.


Horse Science: Functional Anatom y and Action Pa g e 3June 1989Since both conformation and action need to be includedCoarseness about the head indicates a coarse body, lacking in light horse evaluation, the basic conformation featuresquality. The ear should be medium size, attractively set and tending to affect action must be understood. The relationshipcarried at a 45 degree angle to the axis of the head. Large, of body parts to performance (form to function) will be herefull, prominent eyes of a clear deep color are desired. Small discussed with the body of the horse divided into four areas:blue eyes are considered weak. Small narrow, squinty eyes 1. Head and Neck, 2. Fore Quarters, 3. Body or Trunk, 4.are often correlated with coarseness in quality and a lazy, Rear Quarters.sluggish, disposition. of prime importance because the horse cannot force air intoHEAD AND NECKThe ideal head for each breed is described by the association publications. The descriptions all say the head should be broad in the forehead and between the eyes, short from the eyes to the nostrils and deep in the jaws. These words mean only that the head should be in proportion to the parts of the body of the horse. The proportion of the head tends to be an indication of body proportions. For example, a long narrow head indicates a long, shallow, narrow body. Large nostrils allow for a maximum air intake and are the lungs through the mouth as is possible in other species of animals. All breathing of air by the horse must be done through the nostrils. All horses, both long and short necked ones, have seven cervical vertebrae. The shape of the neck is due largely to the amount and shape of the muscular tissues. The neck should be long, lean, and attached high up on shoulders with prominent withers. The lower part of the neck should be attached above the point of the shoulders. The throat latch should be cleancut and free from thick, meaty or fatty tissue to facilitate movement of the head at the poll and allow easy breathing.


Horse Science: Functional Anatom y and Action Pa g e 4June 1989Length of neck plays an important part in length ofshoulders are usually associated with short, steep pasterns stride. Over the neck lie several layers of muscles, some ofgiving a hard, jolting ride because of decreased shock which control the movement of the scapula or shoulderabsorption. blade, the arm, and indirectly the forearm. The muscles thatA long sloping shoulder also forms a more desirable control leg movements terminate at the knee. Cannon,base for neck attachment giving a better balanced, more pastern and foot action is controlled by ligaments andattractive horse. tendons. Larger neck muscles allow more muscle contraction extending the arm further and raising the forearm higher. This results in a longer stride. Another set of muscles extend from the front of the neck to the shoulder blade. Longer muscles here allow more shoulder blade movement and thus a longer stride. A thick neck adds excess weight to the front end. This causes increased shock to the front legs because they ordinarily carry two-thirds of the body weight of the horse. A thick neck also decreases head movement giving slow, awkward turns.FORE QUARTERSThe withers should be prominent or high and well The back which must also be short and heavily muscled defined. They should extend rearward about one-quarter ofgets additional support from the rib cage. Often weak backs the distance from the fore to the rear flanks. This is notresult from weak loins. possible unless the shoulder is long and has about a 45 A short back and loin coupled with desirable shoulder degree slope. Such withers give the horse opportunity toand withers results in a long underline. However, a long have a long stride besides providing a good seat for theunderline does not insure a large body capacity unless it is saddle. combined with long, deep, well sprung ribs. This The shoulder should be long, flat and smooth, with a 45combination of short back and loin, long underline and long, degree slope. This allows for increased shoulder movementdeep, well sprung ribs insures ample capacity for breathing which determines the arm movement and affects the stride.and consuming feed. In a steep-shouldered horse the arm does not extend very far Length of underline also affects freedom of leg forward during movement. This decreases extension of themovement. A short underline can cause a horse to forge. forearm and gives a short stride. Accordingly the slope ofThis is striking the undersurface of the front foot with the the shoulder increases length of the muscles and allows fortoe of the rear foot. more contraction and greater range of movement of the front leg. The legs of the horse should be attached to the trunk to give the appearance of being on the four corners of the body. When viewed from the front, the cannons should descend from the center of the knees. Cannon bones should give the appearance of being flat when viewed from the side. This doesn't mean that the bones themselves are flat, but that splint bones and tendons and ligaments are set apart, well tied and give support at the posterior of the legs. The front feet should be large, symmetrical and set at the same angle as the pastern. The foot should be especially wide at the heel and have considerable height at the heel as long as it is in keeping with the desired angle. When viewed from the side the best combination of length for the various parts of the front quarter calls for a long shoulder, short arm, long forearm and short cannon. This gives a longer, more elastic stride and more speed. A steep shoulder coupled with a long arm, short forearm and long cannon is the most undesirable shoulder and leg structure. This gives a severely shortened stride. SteepTRUNK OR BODYThe trunk or body of the horse should be deep and broad. The back should be short and the loin wide and smooth. The back and loin together make up the top line which must be strong to protect internal organs, bear the weight of the rider and transmit to the front end the propulsion generated by the hind legs. The loin has no bone structure for support, making it the weakest part of the top line. The loin is a bridge between the rib cage and the hips. In order for the loin to perform its function of transmitting power from the rear to front end, it must be short and heavily muscled.REAR QUARTERS


Horse Science: Functional Anatom y and Action Pa g e 5June 1989The croup or rump should be long, wide and level. This2) Horses with low, rounding withers or thick withers often is the area from the loin to the tail head. Although the slopehang low-headed in the bridle and handle front legs of the croup differs with light horse breeds, a level croup hasclumsily. They often forge. longer muscles that enable a horse to take long strides and3) Length and slope of shoulders tends to correspond to maintain speed for great distance. A more sloping croup setslength and slope of pasterns. Properly sloped shoulders and the rear legs further under the horse so he may make apasterns (45 degrees) are related to a springy stride. Length quicker start with the more powerful stride. Regardless ofof shoulders and pasterns is related to the length of stride. breed or slope to the croup, it should be long so the croup4) Long forearms and gaskins are related to length of stride. muscles can make maximum contraction. All muscles in the5) Horses standing straight on front feet are more apt to croup and thigh must be strong to supply the power from the show straight stride and true action. rear quarters to propel the horse.6) Short, straight shoulders give a short, straight stride with Adequate gaskin muscling is desired. The outer gaskinconcussion. muscles help to pull the leg forward and enable propulsion,7) If the front legs are set far out on the corners of the body, giving the horse a long, powerful stride.a rolling, laboring action in front will result. This condition The powerful gaskin muscling also gives strength to theoften goes with thick withers and straight shoulders. legs in turning and pivoting.8) When points of the hocks turn slightly inward with points The rear quarter is comparable to the forequarter in thatof the toes slightly outward and the rear cannons parallel, a long croup, short thigh, long gaskin and short cannon givessuch a position of the rear legs is related to collected, rather the best stride.than spraddled, action behind. 9) When points of the hocks turn outward, often a defect inActionA long, straight, free elastic stride and coordinated, collected action is desirable. Excess lateral movement of the feet and legs reduces efficiency. Action is affected by the set of the feet and legs as well as by the anatomical characteristics already mentioned. Fairly close hock action with the hind legs working beneath the body is essential.EXAMPLES OF ANATOMICAL FEATURES RELATING FORM TO ACTION1) A thick neck and filled throat latch gives a lack of flexion of the head and slow, awkward turns. action called limber hocks or rotating hocks occurs. 10) A calf-kneed position of the front legs gives a pounding gait and hard concussion of feet at completion of the stride. 11) A pigeon toed horse will paddle or wing out when he travels. 12) A splay-footed or toe-wide horse will dish or wing in when he moves. 13) A straight stilty angle of pasterns will give a stilty action and may give cocked ankles or other unsoundnesses such as sidebones.


Horse Science: Functional Anatom y and Action Pa g e 6June 1989NOTES


Horse Science: Functional Anatom y and Action Pa g e 7June 1989NOTES


COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, Christine Ta y lor Waddill, Director, in cooperation with the United States Department of A g riculture, publishes this information to further the purpose of the Ma y 8 and June 30, 1914 Acts of Con g ress; and is authorized to provide research, educational information and other services onl y to individuals and institutions that function without re g ard to race, color, a g e, sex, handicap or national ori g in. The information in this publication is available in alternate formats. Sin g le copies of extension publications (excludin g 4-H and y outh publications) are available free to Florida residents from count y extension offices. Information on copies for out-of-state purchase is available from Publications Distribution Center, Universit y of Florida, PO Box 110011, Gainesville, FL 32611-0011. Information about alternate formats is available from Educational Media and Services, Universit y of Florida, PO Box 110810, Gainesville, FL 32611-0810. This information was published June 1989 as CO 201, which is superseded b y 4HHSG01, Florida Cooperative Extension Service. 1.This document is section 2 of 14 of 4HHSG01, which supersedes CO 201, one of a series of the 4-H Youth Development Pro g ram, Florida Cooperative Extension Service, Institute of Food and A g ricultural Sciences, Universit y of Florida. Date first printed Au g ust 1965. Date revised June 1989. Please visit the FAIRS Website at 2.Joe B. Johnson, Washin g ton State Universit y Debbie Glauer, member of 4-H Animal Science Desi g n Team, Department of Famil y Youth and Communit y Science, Cooperative Extension Service, Institute of Food and A g ricultural Sciences, Universit y of Florida, Gainesville, 32611.