172 THE SURGICAL ANATOMY OF THE HORSE 



iliac vessels, it reaches the origin of the obturator artery, the course oi 

 which it now follows into the pelvis. Arriving at the upper face of 

 the pubic bone, it runs obliquely downwards and backwards along the 

 obturator groove to the obturator foramen. This foramen is covered 

 superiorly by the obturator internus muscle, and beneath this muscle the 

 nerve, with its accompanying artery, passes. The nerve now leaves the 

 pelvis through the obturator foramen by dipping downwards and piercing 

 the obturator membrane which closes the foramen in the living animal. 

 Splitting usually into two filaments, these pass through the obturator 

 externus muscle from above downwards, and make their appearance on 

 its inferior aspect, where one nerve will be found towards the front of 

 the muscle and the other posteriorly. 



The terminal ramifications of the nerve are distributed to the 

 obturator externus, the adductor magnus, the adductor parvus, the 

 pectineus, and gracilis muscles. The longest is the filament which 

 runs to the gracilis, along the inner face of which muscle it descends, 

 after making its appearance in the space between it and the pectineus. 



PARALYSIS OF THE OBTURATOR NERVE 



From the anatomical description of the course, distribution, and 

 relations of this nerve which has been given above it will be seen that 

 the nerve comes into direct relationship with the pubic bone in front of 

 the obturator foramen, and also that the muscles to which the nerve is 

 distributed are adductors of the limb, all of which are placed on the inner 

 aspect of the thigh. These are points of great importance in dealing with 

 paralysis of the nerve, for it will be readily understood that the formation 

 of a callus as a result of fracture of the pubic bone in front of the foramen, 

 will undoubtedly cause pressure to be placed on the nerve, and paralysis 

 is a very probable result. 



Lameness due to inability of the muscles supplied by this nerve has 



