116 



DISSECTION OF THE BUTTOCK. 



The sacral 

 nerves are 

 united 

 beneath 

 gluteus : 



cutaneous 

 offsets. 



Gluteus 

 inedius 



arises from 

 hip-bone, 



and inserted 

 into tro- 

 chanter : 



relations ; 



use with 



limb 



hanging, 



both limbs 

 fixed, 



in standing 

 on one leg, 



and walking. 



Detach 



gluteus 

 inedius to 

 see gluteal 

 vessels 



and nerve. 



Gluteal 

 artery is 



divided into 

 two : 



superficial 



and deep 

 parts ; 



SACRAL NERVES. The external pieces of the posterior primary 

 branches of the first three sacral nerves, after passing outwards 

 beneath the multifidus spinae, are joined to one another by loops 

 on the surface of the great sacro-sciatic ligament. 



Two or three cutaneous offsets are derived from this inter- 

 communication, and pierce the fibres of the gluteus maximus to be 

 distributed on its surface as already seen. 



The GLUTEUS MEDIUS (fig. 48, A) is triangular in form, with its 

 base at the iliac crest, and apex at the femur. It arises from the 

 outer surface of the ilium between the crest and the superior curved 

 line above, and the middle curved line below (fig. 47) ; and many 

 superficial fibres come from the strong fascia covering the front 

 of the muscle. The fibres converge to a tendon, which is inserted 

 into an impression running downwards and forwards across the 

 outer surface of the great trochanter, extending from the tip 

 behind to the root in front (fig. 61, p. 158). 



The superficial surface is concealed in part by the gluteus maxi- 

 mus ; and the deep is in contact with the gluteus minimus, and 

 the gluteal vessels and nerve. The anterior border lies over 

 the glutens minimus, and is in contact with the tensor fasciae 

 femoris. The posterior is contiguous to the pyriformis, only the 

 superficial part of the gluteal vessels intervening. A small bursa 

 is interposed between the tendon of insertion and the trochanter. 



Action. The whole muscle abducts the hanging femur ; and the 

 anterior fibres rotate the limb inwards. 



Both limbs resting on the ground, the muscles assist in fixing the 

 pelvis. In standing on one leg this gluteus will aid in balancing 

 the pelvis on the top of the femur, and will draw the body over to 

 the same side. 



In walking the fore part of the muscle acts in rotating the pelvis 

 over the fixed limb. 



Dissection. The glutens medius is now to be detached from 

 the pelvis, and partly separated from the gluteus minimus beneath, 

 so that the gluteal vessels and the superior gluteal nerve may come 

 into view. The two chief branches of the artery one being near 

 the upper border of the gluteus minimus, and the other lower down 

 are to be traced beneath the fleshy fibres as the reflection of the 

 gluteus is proceeded with ; and the main piece of the nerve is to 

 be followed forwards to the tensor fascia femoris muscle. The 

 branches of the artery and nerve to the gluteus medius will be cut 

 in removing that muscle. 



The GLUTEAL ARTERY is the largest branch of the internal iliac, 

 and issues from the pelvis above the pyriformis muscle, where it 

 at once divides into superficial and deep parts : 



The superficial part (fig. 48) enters the under surface of the 

 gluteus maximus and ramifies in that muscle. Some terminal 

 twigs pass inwards over the sacrum, and others are given to 

 the integuments. 



The deep part (fig. 50, a, p. 122) is the continuation of the artery, 

 and subdivides into two pieces which run between the two smaller 



