288 THE INFERIOR EXTREMITY 



attached by fibre strands to the glutaeus maximus and to the 

 tuberosity. Immediately medial and superior to the ischial 

 tuberosity the deep fibres of the muscle spring from the super- 

 ficial surface of the sacro-tuberous ligament; detach them 

 carefully from the ligament and secure the perforating cutaneous 

 nerve and the coccygeal branches of the inferior gluteal artery 

 which pierce the ligament. The arteries must be divided in order 

 that the reflection of the muscle can be continued, but the nerve 

 should if possible be preserved. Continue the detachment of 

 the muscle from the sacro-tuberous ligament until the margins 

 of the sacrum and coccyx are reached, and as they are approached 

 look for the posterior branches of the sacral nerves which form 

 a plexus on the superficial surface of the ligament deep to the 

 muscle. 



The method of dissection suggested above is one best adapted 

 to avoid injury to the branches of the inferior gluteal nerve 

 which supplies the muscle ; and it gives a view of the structures 

 subjacent to the muscle similar to that obtained by the surgeon 

 operating on the proximal part of the sciatic nerve. 



The method of dissection previously adopted in this Manual 

 was to detach the muscle from its origin from the ilium, the 

 sacrum, the coccyx, and the sacro-tuberous ligament, and to 

 throw it towards its insertion. That method also gives an 

 excellent display of the subjacent structures, from a purely 

 anatomical point of view, and the student who is dissecting the 

 buttock for the second time might employ it with advantage, 

 but it is not a plan which could be adopted by the surgeon. The 

 dissector who employs that method must commence by clearing 

 the upper and lower borders of the muscle. When that has 

 been done the left hand must be insinuated between the muscle 

 and the deeper structures, on the medial side of the greater 

 trochanter, either from above or from below according to the 

 side on which the limb is being dissected. Then, when the 

 muscle has been gently raised from the deeper structures the 

 reflection should be commenced, but the plan to be adopted 

 is different on the two sides. On the left side the muscle must 

 be detached from its origins from above downwards, commencing 

 at the posterior part of the ilium. When the surface of the 

 dorsum ilii from which it springs is cleared the upper margin 

 of the greater sciatic notch is reached. There the dissector must 

 proceed with caution, because through the notch pass the 

 gluteal vessels, and their branches enter the deep surface of the 

 glutseus maximus muscle. When these are secured the muscle 

 must be detached from the side of the sacrum ; then the piri- 

 formis muscle, emerging from under cover of the sacrum, comes 

 into sight. The muscular fibres may now be raised from the 

 surface of the sacro-tuberous ligament and separated from the 

 side of the coccyx. As this is being done, care should be taken 

 to preserve the three sacral cutaneous nerves intact, in order 

 that they may be subsequently traced to their origins. As the 

 surface of the sacro-tuberous ligament is gradually laid bare, 

 a number of small arteries (the coccygeal branches of the inferior 

 gluteal artery) will be seen piercing it and immediately sinking 

 into the substance of the glutaeus maximus. These cannot be 

 retained. It is necessary to sever them in order that the muscle 

 may be freed. The perforating cutaneous nerve, which winds 



