GLUTEAL REGION 283 



sacral nerves, and they ramify, as in other regions, in the 

 superficial fascia on their way towards their terminations. 

 The nerves which must be sought for are 



Lateral branch of last thoracic. 

 Lateral branch of the ilio-hypogastric. 

 Twigs from the posterior branch of 

 the lateral cutaneous nerve of the 



Branches of anterior rami of 

 spinal nerves. 



thigh. 

 Twigs from the posterior cutaneous 



nerve of the thigh. 

 .The perforating cutaneous nerve. 



Branches of posterior rami of f Br ches from the three upper lumbar 



spinal nerves. 1 Ti^T' 



[Three branches from the sacral nerves. 



The branches of the sacral nerves supply the skin of the 

 lower and medial area of the buttock. The lumbar nerves 

 are distributed to the upper part of the medial area and to 

 the upper two-thirds of the intermediate area. The lateral 

 branches of the ilio-hypogastric, the last thoracic nerve, and 

 the lateral cutaneous nerve of the thigh supply the lateral 

 area, and the lower area along the fold of the buttock receives 

 the perforating cutaneous nerve and twigs from the posterior 

 cutaneous nerve of the thigh (Fig. 127). 



Dissection. Seek first for the branches of the posterior rami 

 of the sacral nerves. Make an incision through the superficial 

 fascia along a line, commencing 2 cm. medial to the posterior 

 superior spine of the ilium and terminating at the tip of the 

 coccyx. Then reflect the lateral part of the superficial fascia 

 away from the median plane and secure the nerves as they 

 pierce the deep fascia superficial to the sacral and coccygeal 

 origins of the glutaeus maximus muscle. They are usually three 

 in number ; all are small, but the middle of the three is usually 

 the largest of the series, and as a rule they are situated about 

 25 mm. from one another. 



The branches of the posterior rami of the lumbar nerves 

 should next be sought. Make an incision into but not through 

 the superficial fascia along the line of the crest of the ilium. 

 The object of the incision is to enable the dissector to raise a 

 superficial layer of the superficial fascia, and its depth must 

 vary with the obesity of the subject. In a very fat subject it 

 may be 3 or 4 mm. deep, but in a thin subject it must not be 

 more than 2 mm. deep. After the incision is made, raise a 

 superficial layer of the lower part of the superficial fascia, throw 

 it towards the trochanter major, and secure twigs of the lumbar 

 nerves as they pass from the deeper to the more superficial layers 

 of the fascia. As soon as a twig is found, follow it towards the 

 iliac crest ; it will lead to the trunk from which the twig issues. 

 As soon as the trunk is secured, trace it and its branches towards 

 their terminations. As the branches are being cleaned twigs 

 from the adjacent lumbar nerves are certain to be exposed, for 



