Sakralplexatet

Sakralplexatet, known in English as the sacral plexus, is a network of nerves located in the pelvis. It is formed by the anterior rami of the lower lumbar and its extending sacral nerves (L4 to S4), with contributions from the lumbosacral trunk (L4–L5). The plexus lies on the anterior surface of the piriformis muscle within the pelvic cavity and gives rise to a number of major nerves that innervate the lower limb and perineum.

Major branches of the sacral plexus include the sciatic nerve (L4–S3), the superior gluteal nerve (L4–S1), the inferior gluteal nerve (L5–S2), the pudendal nerve (S2–S4), and the posterior cutaneous nerve of the thigh (S1–S3). It also provides nerves to the obturator internus and to the gemellus and quadratus femoris muscles, among others. The sciatic nerve is the largest branch and typically exits the pelvis through the greater sciatic foramen below the piriformis, then divides into the tibial and common peroneal nerves in the thigh. The superior gluteal nerve leaves the pelvis above the piriformis, while the inferior gluteal nerve exits below it. The pudendal nerve travels through the greater sciatic foramen, winds around the ischial spine, and re-enters the pelvis via the lesser sciatic foramen to reach the perineum, where it supplies motor and sensory innervation to the external genitalia and perineal muscles.

Autonomic fibers from the sacral levels join pelvic splanchnic nerves (S2–S4) to contribute to the autonomic innervation of pelvic organs via the inferior hypogastric plexus. Clinically, dysfunction or compression of the sacral plexus can cause pain, weakness, or sensory loss in the buttock, thigh, leg, foot, or perineum.