Anatomy of the lumbar and sacral plexuses and lower limb peripheral neuropathies

The lumbosacral plexus originates from the anterior rami of the lumbar and sacral nerve roots forming a network of nerves which supply the lower half of the body. The lumbar plexus (L1–L4) is situated within the upper two-thirds of psoas major and gives rise to the iliohypogastric nerve, ilioinguinal nerve, genitofemoral nerve, lateral femoral cutaneous nerve, femoral nerve and obturator nerve. The sacral plexus (L4–S4) is located within the pelvis and gives rise to the superior gluteal nerve, inferior gluteal nerve, sciatic nerve, posterior cutaneous nerve, perforating cutaneous nerve and the pudendal nerve. Peripheral neuropathy of these nerves may occur from an autoimmune, inflammatory, endocrine, infective, congenital, traumatic, neoplastic, vascular, degenerative or metabolic cause. This article will give an overview of the relevant anatomy of the lumbosacral plexus and neuropathies which affect the peripheral nerves of the lower limb.