GLUTEAL PARALYSIS 175 



edge of the middle gluteus, and which is expended in the posterior arm 

 of the superficial gluteus. 



The inferior member of the posterior set appears in close proximity 

 to the posterior border of the great sciatic nerve. It also runs downwards 

 and backwards on the outer surface of the great sacro-sciatic ligament. 

 It splits into two portions, the outer of which curves over the outer 

 aspect ot the tuber ischii, and about six inches below the summit of the 

 tuber, becomes superficially placed and is distributed on the posterior 

 aspect ot the thigh. The inner of the tv^o divisions ultimately joins a 

 branch from the internal pudic nerve and is distributed to the perineal 

 structures. During its course this division gives off a number of small 

 branches, which are distributed to the semitendinosus muscle. 



GLUTEAL PARALYSIS 



From our description of the gluteal nerves it will be seen that they 

 are in a position in which they are extremely well protected from injury. 

 The nerves themselves are tiny filaments which leave the pelvis and pass 

 almost directly to the muscles which they supply. The great thickness of 

 the muscular mass which covers them afi^ords them ample protection from 

 external injury. One filament is, as already stated, intimately related to 

 the neck of the ilium, and is in consequence subjected to risk of injury in 

 cases of fracture in this situation. The only muscle supplied by this 

 branch, however, is the tensor vagins temoris, and consequently paralysis 

 of the nerve would not be followed by very serious consequences. 



Similarly, one filament from the posterior set might be injured in 

 cases of fracture of the tuber ischii. But this nerve does not supply any 

 muscle, for it becomes cutaneous a few inches below the tuber. The 

 filaments which supply the gluteal muscles are not subjected to any such 

 risk of injury, since they do not bear an intimate relationship to any part 

 of the skeleton. Consequently paralysis ot these muscles is rare. Moller 



