LAMENESS IN THE FORE LEG 



79 



In complete paralysis, the joints of the affected limb with the 

 exception of the shoulder are usually flexed when the horse is 

 resting. In consequence of loss of power in the triceps and an- 

 terior ])rachial muscles, the arm is extended and straightened on 

 the shoulder, the scapulohumeral angle is open, and the elbow 

 depressed. The forearm is flexed on the arm by the contraction 

 of the coracoradialis (biceps brachii), while the metacarpus and 

 phalanges are bent by the action of the posterior antibrachial 

 iiuiscles. The knee is carried in advance, level with, or in front 

 of, a vertical line dropped from the point of the shoulder. The 

 hoof is usually rested on the toe, but when advanced beyond the 

 above mentioned vertical line, it may be placed flat on the 



Fig. 9 — Merillat'.s method of fixing carpus in radial paralysis. Courtesy, 

 Alex. Eger. 



ground, the joints then being less markedly bent. When the 

 limb as a whole is flexed, it may be brought into normal position 

 by thrusting back the knee with sufficient force to counteract the 

 action of the flexor muscles. 



When made to walk, the animal l)eing unable to exert muscular 

 action with the paralyzed structures, limply carries the member 

 as a whole, and there is shortening of the anterior portion of 

 the stride. There ])eing loss of function of the triceps brachii, 

 it is impossible for the subject to straighten the leg in the normal 

 position for supporting weight ; therefore, any attempt to bear 



