The five lumbar nerves [L1-L5] emerge below the L1 to L5 vertebrae, respectively.
The anterior divisions of the lumbar, sacral, and coccygeal nerves form the lumbosacral plexus, the first lumbar nerve being frequently joined by a branch from the twelfth thoracic. For descriptive purposes this plexus is usually divided into three parts—the lumbar, sacral, and pudendal plexuses.
The medial branches of the posterior rami (posterior divisions) of the lumbar nerves run close to the articular processes of the vertebræ and end in the Multifidus. The lateral branches supply the Sacrospinalis. The upper three give off cutaneous nerves which pierce the aponeurosis of the Latissimus dorsi at the lateral border of the Sacrospinalis and descend across the posterior part of the iliac crest to the skin of the buttock some of their twigs running as far as the level of the greater trochanter.