Lumbosacral plexus

Lumbosacral plexus (plexus lumbosacralis) provides an innervation of lower limbs, including the pelvis and the surrounding wall of the abdomen (Fig. 1-3).
The upper part of the lumbosacral plexus - lumbar plexus (plexus lumbalis) - formed front of the three upper branches of the lumbar spinal nerves and anastomoses with XII thoracal and IV lumbar nerves. It lies deep in the lumbar muscle and gives the following nerves; the iliac-hypogastric (n. iliohypogastricus; Th-L(I), ilio-inguinal (n. ilioinguinalis; L(I), femoral-sexual (n. genitofemoralis; LI-LII), locking (n. obturatorius; LII-LIV), hip (n. femoralis; LII-LIV) and external cutaneous nerve of thigh (n. cutaneus femoris lat.; LII-LIII). All these nerves are the sources of innervation of the skin in the lower segments of the abdomen, anterior, lateral and medial surface of the femur, the genital area (front), and the muscles of the abdomen on the border with pelvis, front and medial groups of muscles of the thigh. Long branch femoral nerve - saphenous nerve (n. saphenus) - innervates the skin of the anterior surface of the tibia and the medial edge of the foot.

Fig. 1. General view of the lumbosacral plexus:
1 - n. intercostalis XII (n. subcostalis);
2 - n. iliohypogastricus;
3 - n. ilioinguinalis;
4 - m. psoas;
5 - n. cutaneus femoris lat.;
6 - r. genitalis (n. genitofemoralis);
7 - rr. musculares (plexus lumbalis) m. iliacus;
8 - r. femoralis (n. genitofemoralis);
9 - lig. inguinale;
10 - n. femoralis;
11 - n. saphenus;
12 - n. obturatorius;
13 - plexus sacralis;
14 - n. cutaneus femoris lat.;
15 - ganglia sympatica sacralia;
16 - truncus lumbosacralis;
17 - promontorium;
18 - plexus lumbalis;
19 - truncus sympathicus.

Fig. 2. The course nerves lumbosacral plexus in the lower limbs (front): 1 - truncus lumbosacralis; 2 - plexus sacralis 3 - r. posterior n. obturatorii; 4 - r. anterior n. obturatorii; 5 - r. cutaneus n. obturatorii; b - r. infrapatellaris; 7 - n. saphenus; s - n. peroneus superficialis; 9 - n. peroneus profundus; 10 - n. peroneus communis; 11 - n. femoralis; 12 - n. cutaneus femoris lat.; 13 - n. obturatorius; 14 - n. ilioinguinalis; 15 - n. iliohypogastricus; 16 - r. genitofemoralis; 17 - r. femoralis n. genitofemoralis 18 - n. intercostalis XII.

Fig. 3. The course nerves lumbosacral plexus in the right lower limb (rear view, chart): 1 - n. gluteus sup.; 2 - n. gluteus inf.; 3 - n. peroneus communis; 4 - r. communicans peroneus; 5, 6 - n. suralis; 7 - n. tibialis; 8 - n. ischiadicus; 9 - n. cutaneus femoris lateralis; 10 - nn. clunium inferiores; 11 - lig. sacrotuberale; 12 - foramen infrapiriforme; 13 - n. pudendus; 14 - truncus lumbosacralis.

The lower part of the lumbosacral plexus, sacral plexus (plexus sacralis) - presents a major trunks on the back wall of the small pelvis. In the formation plexus participate front branch fourth and fifth lumbar nerves that form the lumbosacral trunk (trunous lumbosacralis), front branch of all sacral, and coccygeal spinal nerves. Connection of part IV of the sacral nerve, front branch of V sacral, and coccygeal nerves considered as PC plexus (plexus coccygeus), Innervate the skin of the perineum posterior to the anus. Sacral plexus, sending through a large sciatic hole in the top and bottom of the buttocks (nn. glutei sup. et inf.), sciatic (n. ischiadicus) and private parts nerves (n. pudendus), rear cutaneous nerve of thigh (n. cutaneus femoris post.), innervates the skin of the buttocks, genitals (rear), rear surface of the femur, tibia and almost all of the foot, as well as the muscles of the perineum, pelvis, hips (rear group), all the muscles of the leg and foot. The greatest surface of the skin and muscles of the legs innervates the largest nerve in the body - sciatic divisible in the hollow of the knee to the tibia and the common peroneal nerve, n. tibialis et n. peroneus communis).
Lumbosacral plexus is connected with the sympathetic trunk, and in the area of SII-SIV forms the pelvic nerves that come into the lower hypogastric plexus and Innervate the pelvic organs.
Pathology lumbosacral plexus-see Neuralgia, Neuritis, Plexitis, Radiculitis.
Cm. also Sacral region and the Lumbar region.