Description: Nerve roots from T12 to L4 contribute to the lumbar plexus, and those from L4 to S4, to the sacral plexus. These are commonly considered as the lumbosacral plexus. The lumbar portion innervates the antero-lateral, lower abdominal wall, the inguinal region, and a small area of the thigh and perineum antero-medially. The sacral plexsus is formed by descending trunks from the lumbar plexsus, and the anterior rami of S1-S4. It serves the pelvic organs, the thigh posteriorly, and most of the lower leg.; The sacral trunks divide into anterior and posterior divisions on the surface of the piriformis m. The superior gluteal n. (posterior trunk) traverses the greater foramen superior to the piriformis (along with the a.) to supply the gluteus medius and minimus m., but distally, the major part of the plexsus (ant. trunk) forms the body's largest peripheral n, the sciatic. The anterior trunk, supplying somatic innervation, also supplies the pudendal n. to the levator ani and coccygeus m., and the vagina and perineum, and the pelvic splanchnic nerves, along with branches to the int. obturator n. and post. cutaneous n. The pudendal n. divides into the inferior rectal n., the labial n., and the perineal n. The autonomic innervation (postganglionic) consists of the sympathetic n. and the parasympathetic n. The sympathetic n. reach the perineum around blood vessels, and by the hypogastric n. The distal ureters, the bladder and the uterus are targets of these n. The parasympathetic n. (S2-S4) form the pelvic n.that distributes axons beneath the peritoneum over the sacrum to intramural ganglia in the lower rectum, bladder wall and neck, the clitoris, the ovaries and uterus. The sensory n. to the urethra, the vagina, and the anal canal are via single neurons running along with somatic n., back to the dorsal horns of the spinal cord.