1210 SURFACE AND SURGICAL ANATOMY. 
extends downwards and somewhat backwards from the anterior end of the crest, to 
join the iho-tibial band below the root of the great trochanter. 
The gluteal artery reaches the buttock mmmediately below the upper border of 
the great sacro-sciatic foramen, opposite a point corresponding to the junction of 
the upper and middle thirds of a line drawn from the posterior superior iliac spine 
to the upper border of the great trochanter. To expose the vessel, the incision 
should be made along this line, which has the advantage of running parallel to the 
fibres of the gluteus maximus, as well as parallel to the interval between the 
eluteus medius and pyriformis muscles. 
The great sciatic nerve enters the buttock at a pomt corresponding to the junc- 
tion of the wpper and middle thirds of a line drawn from the posterior superior 
iliac spine to the ischial tuberosity; from this point the nerve passes downwards 
and shehtly outwards upon the ischium to a point midway between its tuberosity 
and the vreat trochanter. The spine of the ischium and the pudic vessels are 
situated opposite the junction of the lower and middle thirds of the above line. The 
vessels and nerves which enter the buttock through the great sacro-sciatic foramen 
below the pyriformis, may be exposed through an incision below and parallel to 
that above described for exposing the eluteal artery, viz. an incision corresponding 
to the middle two-fourths of a line extending from the upper end of the gluteal 
cleft to the root of the great trochanter; the deep landmarks are the lower porder 
of the pyriformis and the root of the ischial spine. 
THE BACK OF THE THIGH. 
The hamstring muscles, and especially the tendon of the biceps. and semi- 
tendinosus, are thrown into prominence either by standing on tiptoes with the 
Femur Rectus femoris 
| | Vastus internus 
1 Nerve to vastus internus 
| Internal saphenous nerve 
| Sartorius 
: ) Femoral vein \» 
1 
Crureus 
Fe moral artery 
Adductor longus 
Internal saphenous vein 
Vastus externus 
j Adductor magnus 
Profunda arter y 
| Semite ndinosus 
Semimembranosus 
Adductor brevis 
External intermuscular septum l 
Great sciatic nerve Biceps 
Fic. 815.—SEcTION THROUGH THIGH AT THE LEVEL OF THE UPPER PART OF HUNTER’S CANAL. 
knees slightly flexed, or by flexing the leg against resistance. By throwing the 
hamstrings into action, the line of the external intermuscular septum of the thigh is 
