172 SPECIAL ANATOMY. 



pelvis, behind the rectum, Plex. ischiadic, Vasa hypogastrica. ; 

 outside, behind the hip joint; at the superior border, Vasa and 

 Nn. glutxi. 



NOTE. The superior border commonly reaches the top of the 

 incisura ischiad. ; between it and the bone the hernia ischiad. 

 passes through. 



At the inferior border, Vasa and Nn. ischiatici. Or.: 1. Os 

 sacrum (anterior lateral surface, close to foramina sacral, ant. 

 second and third, the n. ischiad.}. 2. Lig. sacro-tuberos. 

 (anterior surface). 3. Incisura ischiadica, superior part. Ins. : 

 Trochanter major (superior edge of the fossa). 



Nerves : glutaus superior and ischiadicus. 



344. 7. .Obturator internus. 



Pos. : triangular, in the pelvis, behind membrana obturatoria, 

 covered before byfasc. pelvis and levator ani ; passes through 

 incis. ischiad, min. around os ischii and horizontally outwards, 

 in the groove between gemelli, behind the neck of the femur, 

 covered by glutssus max. Or. : membr. obturatoria and the 

 whole circumference offoram. obturatorium. Ins. : trochanter 

 major, the lin. intertro chant, post., below pyriformis. 



Nerves: Ischiadicus. 



345. 8. Gemellus superior. 



Pos.: above the tendon of the last muscle, horizontally out- 

 wards. Frequently wanting. Glutxus max. covers both gemelli. 

 Or. : Spina Ischii (inferior border, external surface). Ins.: like 

 the last muscle. 



346. 9. Gemellus inferior. 



Pos. : stronger, below the tendon of obturator intern. Some- 

 times double. Or. ; Tuber ischii (quite above lig. tuber oso-sacr.) 

 Ins. : like the last muscle. Uses : (of 6. to 9.), they rotate the 

 thigh outwards. 



Nerves: ischiadicus, for 8. and 9. 



347. 10. Quadratusfemoris. 



Pos. : transverse, immediately below 9. ; covers before obtu- 

 rator extern, and trochanter minor ; between tuber Ischii and 

 trochanter major, covered by Glutseus max. Or. : tuber ischii 

 (external border) covered by semi-membranos., adductor magnus. 

 Ins. : the vertical line between basis trochant. major and linea 

 aspera. Use : rotates (even the flexed) thigh outwards ; rotates 

 (when standing upon one leg) the trunk to the other side. 



Nerves: ischiadicus. 



