PRACTICAL CONSIDERATIONS: THE BUTTOCKS. 



641 



PRACTICAL CONSIDERATIONS : MUSCLES AND FASCIA 



OF THE BUTTOCKS, HIP, THIGH, AND KNEE. 



I. The Buttocks. — The skin over this region is thick and is closely connected 

 with the superficial fascia, which is abundant, loose, and contains much fat. The skin 

 is richly supplied with nerves from the small sciatic, the external and the perforating 

 cutaneous, the ilio-hypogastric, and the external branches of the posterior division of 

 the lumbar and sacral nerves. It is poorly supplied with blood as compared with 

 other cutaneous areas, and hence usually has a relatively low surface temperature. It 

 is coarse, with numerous sebaceous follicles, and is the site of frequent minor forms of 

 irritation, — chafes, bruises, etc., — and is for these reasons a common seat of superficial 



Fig. 611. 



Gluteus maximus, 

 turned forward 



Pyriformis 



Dislocated head of femur 



Obturator internus 



Greater sciatic nerve 



Quadratus femoris 



Dissection of posterior luxation of left femur towards dorsum of ilium. 



furuncles, which, on account of its intimate union with the underlying fascia and its 

 plentiful nerve-supply, are apt to be very painful. 



The presence of a large quantity of poorly organized fat in the superficial fascia 

 and the frequency of local irritation render the region a favorite seat of lipomata. 



The laxity of the superficial fascia permits effusions of pus or of blood to attain 

 exceptionally large dimensions, and this is encouraged by gravity in the usually 

 dependent position of the part. 



The deep fascia attached to the back of the sacrum and coccyx and to the crest 

 of the ilium covers in the gluteus medius and holds it, with the gluteus minimus, in 

 an osseo-fascial space, as the ilio-psoasis held anteriorly by the iliac fascia (page 624). 

 The posterior space, however, is completely closed superiorly and is open only 

 inferiorly, towards the thigh, and antero-internally, towards the sciatic foramina. 

 Abscesses or extravasations of blood in this space may originate in, or may find their 



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