PARALYSIS OF EXTERNAL POPLITEAL NERVE 169 



PARALYSIS OF THE EXTERNAL POPLITEAL NERVE 



This nerve is in a position which renders it particularly exposed to 

 risk of external injury. Almost immediately beneath the nerve we have 

 a hard, resistant structure in the outer condyle of the femur, so that the 

 parts beneath the nerve do not give when a blow is received over the 

 outer aspect of the limb just above the stifle joint. 



It is not surprising, therefore, that paralysis of this nerve has fre- 

 quently been recorded, and the condition was observed by Goubaux as 

 far back as i 848. 



The muscles affected in these cases are the extensor pedis, the 

 flexor metatarsi, and the peroneus, so that the hock becomes fully 

 extended, whilst the fetlock and interphalangeal joints are extremely 

 flexed, the foot being rested with the anterior portion of the wall on 

 the ground. If a rope be passed round the fetlock and flexion ot 

 the hock and extension of the fetlock and interphalangeal joints be 

 assisted artificially, the animal can walk without difficulty, and places its 

 full weight upon the affected limb. The animal feeds well, and there 

 are no signs of systemic disturbance. Sensation is lost over the area 

 supplied by the continuations of this nerve, i.e., the outer aspect of the leg 

 (musculo-cutaneous and peroneal-cutaneous nerves) and the outer aspect 

 and front of the hock and metatarsal region (cutaneous branches of 

 anterior tibial, musculo-cutaneous, and peroneal-cutaneous nerves). There 

 is no difficulty in detecting by palpation the inability of the muscles 

 named above if the animal be compelled to move forwards. 



Treatment consists in applying a blister along the course of the 

 nerve, and exercising the patient. 



