GLUTEAL REGION 293 



After the branches of the sciatic nerve to the hamstrings 

 have been cleaned, pull the proximal part of the sciatic nerve 

 laterally, to expose the nerve to the quadratus femoris, which 

 lies between the sciatic nerve and the posterior surface of the 

 ischium. The nerve to the quadratus femoris is frequently 

 accompanied by a small branch of the inferior gluteal artery. 

 On the medial side of the nerve to the quadratus femoris, lying 

 on the spine of the ischium, find the nerve to the obturator 

 internus, the internal pudendal vessels, and the pudendal nerve 

 in that order from the lateral to the medial side. Clean away 

 the venae comites of the artery, but carefully preserve the artery 

 itself and the nerves. 



After the nerves and vessels mentioned have been identified 

 and cleaned, proceed to the examination of the muscles which 

 lie deep (anterior) to the sciatic nerve. They are, from above 

 downwards, the superior gemellus, the obturator internus, the 

 inferior gemellus, the quadratus femoris, and the proximal 

 part of the adductor magnus. Emerging between the adjacent 

 borders of the quadratus femoris and the adductor magnus the 

 transverse terminal branch of the medial femoral circumflex 

 artery will be found, and, piercing the adductor magnus at the 

 medial border of the gluteal tuberosity of the femur, in a well- 

 injected subject, the first perforating branch of the profunda 

 artery may be seen. Clean the arteries, and then clean the 

 muscles from above downwards. Note that the obturator 

 internus emerges from the small sciatic foramen and that as it 

 emerges it overlaps both the gemelli, whilst near the trochanter 

 major, toward which all three muscles converge, the gemelli 

 overlap the tendon of the obturator internus. 



After the muscles are cleaned, divide the tendon of the 

 obturator internus about 15 mm. from the lesser sciatic 

 foramen. When the medial part of the tendon is raised and 

 turned backwards the dissector will note that its deep surface 

 is cleft into four or five strands, and that the margin of the 

 lesser sciatic foramen, on which the tendon glides, is covered 

 with smooth cartilage which is raised into ridges corresponding 

 with the grooves on the deep surface of the tendon. A large 

 bursa intervenes between the tendon and the bone. 



Turn next to the hamstring muscles, which spring from the 

 tuberosity of the ischium, and separate the common tendon of 

 the biceps femoris and the semitendinosus from the flattened 

 tendon of the semimembranosus, which lies immediately sub- 

 jacent. Then pull the hamstrings laterally and display the 

 origin of the adductor magnus from the inferior part of the 

 tuber ischii. 



Parts under Cover of the Glutseus Maximus. Four 

 groups of structures lie under cover of the glutaeus maximus, 

 viz., bursae, muscles, vessels and nerves. 



The bursae, which have already been examined (see p. 291), 

 are three in number; (i) a bursa between the middle of the 

 inferior border of the glutaeus maximus and the tuber ischii, 

 (2) the bursa between the tendinous insertion of the glutseus 

 maximus and the trochanter major, and (3), immediately 



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