GLUT^EAL REGION 223 



of the lumbar fascia, at the attachment of the latter to the 

 crest of the ilium. 



From this extensive origin the coarse fasciculi of the 

 muscle proceed obliquely distally and anteriorly towards 

 the proximal portion of the femur, but only a comparatively 

 small proportion of them receive direct insertion into that 

 bone. The greater part of the muscle is inserted into the 

 fascia lata. To be more precise, we may say that the whole 

 of the fibres belonging to the proximal half of the muscle, and 

 the superficial stratum of fibres of the distal half of the 

 muscle, are inserted into the fascia lata. The deeper fibres 

 of the distal half of the muscle, however, are directly attached 

 to the glutaeal tuberosity on the back of the femur (i.e. the 

 ridge which extends from the greater trochanter to the linea 

 aspera). (Fig. 78, p. 209.) The glutseus maximus is supplied 

 by the inferior glutceal nerve. 



Reflection of the Glutseus Maximus. This is by no means an easy 

 dissection. It is best to detach the muscle from its origin and throw it 

 distally towards its insertion. It should be dissected completely away 

 from the various surfaces from which it arises. By this means the general 

 outline of the pelvis becomes more apparent, and the dissector obtains 

 distinct bony landmarks which are most useful in enabling him to localise 

 the various structures he is expected to expose. Let us suppose we are 

 dealing with the left lower limb. As a preliminary step, the two borders 

 of the muscle should be freed and the left hand gently insinuated under the 

 fleshy mass. The muscle must, in the first instance, be detached from the 

 ilium. When the surface on the dorsum ilii from which it springs is 

 cleared the upper margin of the great sciatic notch is reached. Here the 

 dissector must proceed with caution, because through this notch pass the 

 glutaeal vessels, and their branches enter the deep surface of the glutoeus 

 maximus muscle. When these are secured the muscle must be detached 

 from the side of the sacrum, then the piriformis muscle, emerging from 

 under cover of the sacrum, comes into sight. The muscular fibres may now 

 be raised from the surface of the ligamentum sacro-tuberosum and separated 

 from the side of the coccyx. In doing this, care should be taken to preserve 

 the three sacral cutaneous nerves intact, in order that they may be sub- 

 sequently traced to their origins. As the surface of the ligamentum sacro- 

 tuberosum is gradually laid bare, a number of small arteries (the coccygeal 

 branches of the inferior glutoeal artery) will be seen piercing it and 

 immediately sinking into the substance of the glutrcus maximus. These 

 cannot be retained. It is necessary to sever them in order that the muscle 

 may be freed. The perforating branch of the fourth sacral nerve, which 

 winds round the distal border of the glutseus maximus near the coccyx, 

 must also be remembered and traced to the ligamentum sacro-tuberosum 

 which it will be seen to pierce. 



The glutreus maximus is now completely separated from the parts from 

 which it arises, but it cannot be thrown distally towards its insertion. 

 It is still tied to its place by the blood-vessels and nerves which enter its 

 deep surface. These are ( I ) the branches of the superficial division of the 

 s^tper^or glutaal artery which appear at the upper border of the piriformis ; 



