THE GLUTEUS MAXIMUS. 583 



of the sciatic artery : two or three ascend round the edge of the muscle, and 

 are lost in the integuments of the lower part of the buttock ; the remain- 

 ing branches ( 2 ) descend to the thigh, and will be afterwards noticed on it. 



Dissection. The thin and unimportant deep fascia of this region may 

 be disregarded, in order that the great gluteal muscle, which is the most 

 difficult in the body to clean, may be well displayed. Supposing the stu- 

 dent desirous to lay bare the muscle, let him turn aside the cutaneous 

 nerves, and adduct and rotate inwards the limb to make tense the muscu- 

 lar fibres. Having cut through the fat and fascia from the origin to the 

 insertion, let him carry the scalpel along one bundle of fibres at a time in 

 the direction of a line from the sacrum to the femur, until all the coarse 

 fasciculi are cleaned. If the student has a right lirnb, the dissection may 

 be begun at the upper border ; but if a left limb, at the lower margin of 

 the muscle. 



The fasia of the buttock is a prolongation of that enveloping the thigh, 

 and is fixed to the crest of the hip bone, and to the sacrum and coccyx. 

 It is much thicker in front of, than on the glutens maximus, and gives 

 attachment anteriorly to the gluteus medius which it covers. At the edge 

 of the gluteus maximus, the fascia splits to incase the muscle. 



The GLUTEUS MAXIMUS (fig. 199, A ) is the most superficial muscle of 

 the buttock, and reaches from the pelvis to the upper part of the femur. 

 Its origin from the pelvis is partly connected with bone and partly with 

 aponeurosis: Thus, the muscle is attached, from above down, to the pos- 

 terior third of the iliac crest, and to a special impression on the hip bone 

 below it; next, to the aponeurosis covering the multifidus spinge muscle; 

 then to the back of the lowest piece of the sacrum, and the back of the 

 coccyx ; and lastly to the great sacro-sciatic ligament. From this exten- 

 sive origin the fibres are directed outwards to their insertion: About two- 

 thirds of the upper fibres, and a few of the lowest, end in the fascia lata 

 of the outer part of the thigh: and the remainder are fixed for three 

 inches into the lower part of the line leading from the linea aspera to the 

 great trochanter of the femur. 



The gluteus forms the prominence of the buttock, and resembles the 

 deltoid muscle of the arm in the situation, and in the coarseness of its tex- 

 ture. Its cutaneous surface is covered by the common teguments and in- 

 vesting fascia of the limb, and by the superficial nerves and vessels. The 

 parts in contact with the under surface will be seen when the muscle is 

 cut through. The upper border overlays the gluteus medius. And the 

 lower edge, which is longer and thicker than the upper, forms the fold of 

 the nates, and bounds posteriorly the perinatal space ; beneath the lower 

 border the ham-string muscles and the sciatic vessels and nerves issue. 



Action. With the femur hanging the muscle extends the hip-joint by 

 putting back that bone, and abducts and rotates out the limb. 



When the limb is fixed, and the body is raised from a sitting into a 

 standing posture, the gluteus acts as an extensor of the articulation by 

 moving back the pelvis. 



In standing both muscles assist in keeping the pelvis balanced on its 

 props; and in rising from stooping they are the active agents in bringing 

 upright the pelvis. When the body is supported on one leg the muscle 

 can draw the sacrum towards the femur, so as to turn the face to the oppo- 

 site side. 



Dissection (fig. 200). The gluteus maximus is to be cat across near 

 the pelvis, and without injury to the subjacent sacro-sciatic ligament to 



