226 INFERIOR EXTREMITY 



border of the adductor magnus. By separating the con- 

 tiguous margins of the gemellus inferior and quadratus femoris 

 from each other, and looking into the interval between them, 

 the tendon of the obturator externus will be seen as 

 it passes round the neck of the femur to reach the fossa 

 trochanterica. By dealing similarly with the adjacent margins 

 of the quadratus femoris .and the adductor magnus, the lesser 

 trochanter of the femur will be exposed. Lastly, the origin 

 of the hamstring muscles, from the tuber ischiadicum, and the 

 proximal part of the vastus lateralis, arising from the root of 

 the greater trochanter of the femur on its lateral aspect, should 

 be noted. 



In each interval formed by the adjacent margins of the 

 muscles exposed, blood-vessels and nerves, or blood-vessels 

 alone, are to be found. 



Before proceeding to the dissection of these, however, it is well that the 

 student should renew his acquaintance with the skeletal peculiarities of 

 this region. Let him obtain a dried pelvis with the ligaments in situ, and 

 study carefully the position and boundaries of the great and small sciatic 

 notches, and the manner in which they are converted into foramina by the 

 ligamentum sacro-tuberosum (O.T. great sciatic) and ligamentum sacro- 

 spinosum (O.T. small sciatic). Through these foramina important 

 structures issue from the interior of the pelvis into the glutaeal region. 



In the interval between the contiguous margins of the 

 gluta^-us medius and the piriformis muscles, the superior glutaal 

 artery and nerve issue from the pelvis through the great sciatic 

 foramen. In the interval between the piriformis and the 

 gemellus superior two arteries and six nerves must be looked 

 for, as they emerge through the lower part of the great sciatic 

 foramen, viz. : 



... fi. A. glutaea inferior. 



ies ' \ 2. A. pudenda interna. 

 N. ischiadicus. 



N. cutaneus femoris posterior. 

 *j | 3. N. pudendus. 



' es ' ^ 4. N. glutseus inferior. 



5. Nerve to the obturator internus. 



6. Nerve to the quadratus femoris. 



The huge sciatic nerve, together with the inferior glutaeal 

 artery and posterior cutaneous nerve of the thigh, proceed 

 distally in the hollow between the greater trochanter of the 

 femur and the tuber ischiadicum. 



In the interval between the gemellus inferior and the 

 quadratus femoris, the small ascending terminal branch of the 



