BRANCHES OF PROFUNDA ARTERY. 133 



Action. This "hamstring is united with the preceding in its action, use on knee 

 for it 1 >ends the knee and rotates in the tibia; and with the knee 

 straight it will limit flexion of the hip, or extend this joint after ami hip- 

 the femur has been carried forwards. The extension across the J ints > 

 back of the joint serves to keep the posterior ligament clear of the 

 articulation in flexion of the leg. 



When the foot rests on the ground, the seniimembranosus acts on pelvis, 

 on the pelvis like the other hamstring muscles. 



The GREAT SCIATIC NERVE (fig. 53, 2 ) lies on the adductor magnus Great sciatic 

 muscle below the buttock, and divides into the two popliteal nerves 

 about the middle of the thigh, though its point of bifurcation may 

 be carried upwards as far as the pelvis. In this extent the nerve 

 lies along the outer border of the seniimembranosus, and is crossed 

 1 >y the long head of the biceps. 



Branches. Near the buttock it supplies large branches to the supplies 

 flexor muscles, and a small one to the adductor magnus. 



SMALL SCIATIC NERVE -(fig. 53, *). Between the gluteus'maximus small 

 and the ham this small nerve is close beneath the fascia ; but it 

 becomes cutaneous below the knee, and accompanies the external 

 saphenous vein for a short distance. 



Small cutaneous filaments pierce the fascia ; and the largest of cutaneous 

 the.se arises near the popliteal space. 



Dissection, To see the posterior surface of the adductor magnus, Detach the 



IT, T n, i> T . i hamstrings. 



and the branches ot the perforating and anastomotic arteries at the 

 back of the thigh, the hamstring muscles must be detached from 

 the hip-bone and thrown down ; and the branches of arteries and 

 nerves they receive are to be dissected out with care. All the parts 

 are to be cleaned. 



ADDUCTOR MAGNUS MUSCLE (fig. 53, c). At its posterior aspect ^^Jj 

 the large adductor is altogether fleshy, even at the opening in the adductor 

 lower third of the thigh, where the superficial femoral passes through ma s nus - 

 it to become the popliteal ; and the upper fibres which come from 

 the pubic arch appear to form a part almost distinct from those 

 connected with the tuberosity of the ischium. In contact with 

 this surface are the hamstring muscles and the great sciatic nerve. 

 (The muscle will be described later in the dissection of the thigh 

 from the front, p. 167.) 



END OF THE PERFORATING ARTERIES (fig. 53, C, d, e). These Perforating 



branches of the prof unda femoris appear through the adductor artenes : 

 magnus close to the femur, and are directed outwards through the course 

 short head of the biceps and the outer intermuscular septum to the 

 vast us ex t emus and crureus muscles ; but as the first branch is placed 

 higher than the attachment of the biceps, it pierces the glutens 

 maximus in its course. In the extensor muscles they anastomose and ending ; 

 together, and with the transverse and descending branches of the 

 external circumflex artery. 



Muscular branches are furnished by the perforating arteries to offsets to 

 the heads of the biceps ; and a cutaneous offset is given by each to 

 the integuments of the outer side of the thigh, along the line of 

 the outer intermuscular septum. 



