538 SPINAL NERVES. 



beneath the Gluteus maximus with the sciatic artery, and at the lower border of 

 that muscle passes along the back part of the thigh, beneath the fascia lata, to the 

 lower part of the popliteal region, where it pierces the fascia and becomes 

 cutaneous. It then accompanies the external saphenous vein below the middle of 

 the leg, its terminal filaments communicating with the external saphenous nerve. 



The branches of -the small sciatic nerve are muscular (inferior gluteal) and 

 cutaneous. 



The inferior gluteal consist of several large branches given off to the under 

 surface of the Gluteus maximus, near it lower part. 



The cutaneous branches consist of two groups, internal and ascending. 



The internal cutaneous branches are distributed to the skin at the upper and inner 

 side of the thigh, on its posterior aspect. One branch, longer than the rest, the 

 inferior puclendal, curves forward below the tuber ischii, pierces the fascia lata on 

 the outer side of the ramus of that bone, and is distributed to the integument of 

 the scrotum, communicating with the superficial perineal nerve. 



The ascending cutaneous branches consist of two or three filaments, which 

 turn upwards round the lower border of the Gluteus maximus, to supply the 

 integument covering its surface. One or two filaments occasionally descend 

 along the outer side of the thigh, supplying the integument as far as the middle 

 of this region. 



Two or three branches are given off from the lesser sciatic nerve as it descends 

 beneath the fascia of the thigh ; they supply the integument of the back part of 

 the thigh, popliteal region, and upper part of the leg. 



The GREAT SCIATIC NERVE supplies nearly the whole of the integument of the 

 leg, the muscles of the back of the thigh, and of the leg and foot. It is the largest 

 nervous cord in the body, measuring three-quarters of an inch in breadth, and is 

 the continuation of the lower part of the sacral plexus. It passes out of the pelvis 

 through the great sacro-sciatic foramen, below the Pyriformis muscle. It descends 

 between the trochanter major and tuberosity of the ischium, along the back part 

 of the thigh to about its lower third, where it divides into two large branches, the 

 internal and external popliteal nerves. 



This division may take place at any point between the sacral plexus and the 

 lower third of the thigh. When the division occurs at the plexus, the two nerves 

 descend together, side by side ; or they may be separated, at their commencement, 

 by the interposition of part or the whole of the Pyriformis muscle. As the nerve 

 descends along the back of the thigh, it rests at first upon the external rotator 

 muscles, together with the small sciatic nerve and artery, being covered by the 

 Gluteus maximus ; lower down, it lies upon the Adductor magnus, being covered 

 by the long head of the Biceps. 



The branches of the nerve, before its division, are -articular and muscular. 



The articular branches arise from the upper part of the nerve ; they supply the 

 hip-joint, perforating its fibrous capsule posteriorly. These branches are some- 

 times derived from the sacral plexus. 



The muscular branches are distributed to the Flexors of the leg; viz., the 

 Biceps, Semi-tendinosus, and Semi-membranosus, and a branch to the Adductor 

 magnus. These branches are given off beneath the Biceps muscle. 



The INTERNAL POPLITEAL NERVE, the larger of the two terminal branches of 

 the great sciatic nerve, descends along the back part of the thigh through the 

 middle of the popliteal space, to the lower part of the Popliteus muscle, where it 

 passes with the artery beneath the arch of the Soleus, and becomes the posterior 

 tibial. It lies at first very superficial, and at the outer side of the popliteal vessels ; 

 opposite the knee-joint, it is in close relation with these vessels, and crosses the 

 artery to its inner side. 



The branches of this nerve are articular, muscular, and a cutaneous branch, the 

 external or short saphenous nerve. 



The articular branches, usually three in number, supply the knee-joint ; two of 



