The main branch of the spinal nerve. The anterior spinal nervebranches from:
1/ spinal nerves C1 through C4 form the cervical plexus that gives rise to the skin and skeletal muscle nerves of the neck and to the phrenicus nervus, which innervates the diaphragma, the main respiratory muscle
2/ spinal nerves C5 to T1 form the brachial plexus which gives rise to the skin and skeletal muscle nerves of the shoulder and arm,
3/ spinal nerves T2 through T12 form the rib nerves (nervi intercostales),
4/ spinal nerves L1 through S3 form the lumbo-sacral plexus that gives rise to the skin and skeletal muscle nerves of the hip and leg; and
5/ spinal nerves S4 to Co1 form the coccygeus plexus, which gives rise to the nerves of the external genitalia.