Lumbosacral Plexus

While the origin of the various branches of the lumbar plexus varies according to whether the plexus is prefixed, ordinary, or postfixed, it is typically formed by the union of the anterior rami of the first three lumbar nerves and usually a part of the fourth lumbar nerve, and projects laterally and caudally from the intervertebral foramina. This chapter describes the branches of the lumbar plexus including sacral plexus, pudendal plexus, and coccygeal plexus. Each of these branches has sub-branches. The ilioinguinal nerve is usually smaller than the iliohypogastric nerve and arises with it from the first lumbar ventral ramus. The lateral femoral cutaneous nerve can arise from the femoral nerve or as an independent branch of the lumbar plexus. The sacral plexus is formed by the lumbosacral trunk, the first to third sacral ventral rami, and part of the fourth sacral ventral ramus.