740 Paralj'sis of the Radial Nerve. 



case in a liorse is recorded by Kutzner in wliicli there Avas si- 

 multaneous paralysis of the left radial nerve (associated with 

 paralysis of the anconeus) and of the crural nerves. 



Frohner is of the opinion that the cause of the condition lies in the nmseular 

 tissue and that myositis leading to atrophy and paralysis result from excessive 

 strain of the muscdes. Tlie occurrence of muscular paralysis in the horse cannot 

 be denied and the credit of having adduced proof of this principally belongs to 

 Frohner, but the conclusion must not be drawn from observations in which no ex- 

 haustive investigations of the nerves were made that this kind of paralysis is of 

 more frequent occurrence than that of nervous origin. The superficial situation 

 of the radial nerve at the point indicated make it extremely probable that, in the 

 horse particularly, pressure on the nerve is of comparatively common occurrence. 



Symptoms. In view of the fact that radial paralysis is 

 generally due to an injury of the lower portion of the arm, 

 and that in this situation there is only that part of the radial 

 nerve which supplies the muscles below the elbow joint, trau- 

 matic radial paralysis usually shows itself in a paralysis of 

 the extensor muscles lying on the forearm. It is only excep- 

 tionally that the sensory fibers supplying the outer surface of 

 the forearm or the motor fibers of the extensors of the elbow 

 joint are involved. If the injury is inflicted at a still higher 

 level, about the level of the shoulder joint or in the vertebral 

 canal, the paralysis involves the anconeus group of muscles. 



During rest the shoulder and elbow joints are held ex- 

 tended and the rest of the joints flexed (fig. 106). If the limb 

 be forced back by pressure on the carpus, the weight is borne 

 by the limb and the position does not differ from the normal, 

 but if the animal moves the joints are flexed again and the 

 animal cannot straighten the limb. If the animal be made to 

 walk the limb is advanced by means of the extensor muscle 

 of the shoulder until it is vertically under the body or a little 

 further forward, the hoof wall being dragged along the ground. 

 Directly the w^eight is put upon the limb all the joints are 

 flexed, because the foot is not properly placed owing to loss of 

 power of the extensors. It is very difficult for the animal to 

 get up and sometimes quite impossible. The extensor muscles 

 are in a condition of relaxation both during movement and 

 rest, and in somewhat more severe cases atrophy soon sets in. 

 The elbow joint is somewhat lower than on the sound side 

 (Plosz). The sensibility of the skin and the distribution of 

 heat are not in any way abnormal. In some cases there is loss 

 of sensation or evidence of pain in the parts where the nerve 

 ramifies (Bossi, Hebrant). 



If the extensors of the ell)ow are paralyzed at the same time 

 the motor disturbances are much more striking and these mus- 

 cles are also relaxed and atrophy soon occurs. 



If the paralysis is incomplete the motor disturbances are 

 less ol)vious. During rest the animal may, for example, be able 

 to extend the limb to some extent so as to be able to bear some 

 part of the weight on it, but during movement the animal keeps 



