436 A MANUAL OF ANATOMY 



condyle, three tendons may be felt; The most superficial one is 

 that of the semitendinosus, which, though firm, is narrow, and is 

 traceable for some distance above the knee-joint. Underneath it 

 is the tondon of the semimembranosus, and, internal to this, is the 

 slender tendon of the gracilis. The course of the popliteal artery 

 practically coincides with the middle line of the popliteal space, 

 but the vessel can only be felt when the joint is well flexed. During 

 this manipulation the popliteal lymphatic glands, if enlarged, may 

 be detected. 



Back of the Thigh. — ^There is nothing noteworthy in the super- . 

 ficial fascia. The deep fascia will be described in connection with 

 the fascia lata. 



Small Sciatic Nerve. — This nerve arises from the sacral plexus, 

 more particularly from the back of the first, second, and third sacral 

 nerves. It emerges through the lower compartment of the great 

 sacro-sciatic foramen, below the pyriformis. It then passes down- 

 wards between the great trochanter and tuber ischii, resting upon 

 the superficial surface of the great sciatic nerve, and being under 

 cover of the lower part of the gluteus maximus. After escaping 

 from beneath this muscle, it descends in the middle line super- 

 ficial to the hamstring muscles, and beneath the deep fascia cover- 

 ing them, and, passing over the popliteal space, it pierces the 

 deep fascia at the back of the knee-joint. It then enters the back 

 of the leg, and descends as low as about the centre of the calf, 

 in company with the external or short saphenous vein. The 

 nerve is entirely sensory. 



Branches. — ^The branches are gluteal cutaneous, long pudendal 

 nerve of Soemmering, femoral cutaneous, and sural cutaneous. 



The gluteal cutaneous branches are three or four in number, 

 and take a recurrent course, winding round the lower border 

 of the gluteus maximus, and supplying the integument over its 

 lower and outer part. The long pudendal nerve of Soemmering 

 arises at the lower border of the gluteus maximus, and winds 

 inwards towards the anterior part of the perineum, lying a 

 little below the tuber ischii and crossing behind the origins 

 of the hamstring muscles from that prominence. It then pierces 

 the fascia lata fully i inch in front of the tuber ischii, and, 

 passing over the ischio-pubic ramus and through Colles' fascia, 

 it courses forwards and inwards, in company with the two 

 superficial perineal nerves and the superficial perineal artery, 

 to the scrotum in the male and the labium majus in the female. 

 In the anterior part of the perineum it communicates with the 

 two superficial perineal nerves, and with them forms the three 

 long scrotal (or labial) nerves. Its branches are femoral cutaneous, 

 to the upper and inner part of the thigh on its posterior aspect ; and 

 scrotal or labial, to the scrotum or labium majus, according to the 

 sex. The femoral cutaneous branches of the small sciatic supply 

 the integument of the back of the thigh as low as the knee-joint. 

 The sural cutaneous branches are the terminal branches of the nerve. 



