This is a combination of nerves for the supply of the hind-limb. It corresponds with the brachial plexus of the fore-limb in being formed by the inferior branches of the fourth, fifth, and sixth lumbar, and the first and second sacral nerves.
The branches given off from this plexus are as follow: -
2. Anterior or Great Crural Nerve. - This is a nerve of considerable size formed by fibres from the fourth and fifth lumbar roots, and in part also from the loop between the third and fourth. Descending between the psoas magnus and parvus, it passes downwards at the outer side of the external iliac artery under cover of the sartorius, and after crossing the conjoined tendon of the psoas and iliacus muscles, ends in a number of branches, which pass between the vastus interims and rectus femoris to be distributed to the extensors of the legs.
It gives off the internal saphenous nerve, and sends branches to the rectus femoris.
3. The Obturator Nerve is situated beneath the peritoneum on the inner side of the pelvis, and follows the course of the artery of the same name through the obturator foramen to the internal aspect of the thigh. It is derived from the fourth and fifth lumbar roots, and gives branches to the obturator externus, adductors of the thigh, the pectineus and gracilis muscles.
4. The Anterior and Posterior Gluteal Nerves, also called the small sciatic nerves. These nerves leave the pelvis by the great sciatic notch. The anterior gluteal consists of four or five branches, which are distributed to the gluteus medius, the tensor vagina femoris, vastus externus and interims, and the gluteus externus. The posterior gluteal nerve is represented by two branches - a superior and inferior. The superior supplies the superficial gluteus, the middle gluteus, and the biceps femoris. The inferior branch, after passing over the outer side of the tuber ischii, is destined to the skin of the thigh, the semitendinosus, and with a branch of the internal pudic nerve to the structures of the perineum.