Netter's Anatomy Practice Test

The lumbosacral plexus is the network that primarily innervates the muscles of the buttock, pelvis, perineum, and lower limb. It is formed by ventral rami from the lumbar and sacral regions (roughly L1–S4) that come together and give rise to the major nerves of the lower body. For the buttock, nerves such as the gluteal nerves originate from this plexus and supply the gluteal muscles. The perineum receives innervation from nerves like the pudendal nerve, also part of this plexus, and pelvic organs are served by branches within the same network. The entire lower limb depends on nerves that branch from the lumbosacral plexus, including the sciatic nerve for the majority of the leg and foot. In contrast, the brachial plexus serves the upper limb, the lumbar plexus mainly handles the anterior thigh and abdominal wall, and the stratum basale is a skin layer with no neural plexus involvement.