Explain the Posterior Nerve Root
Posterior nerve root consists of sensory nerve fibres, having cell bodies in root ganglions and enter the spinal cord. Immediately after emerging from the intervertebral foramen, each spinal nerve divides into ramus communicants, posterior and anterior ramus. The ramus communicants are part of pre ganglionic sympathetic neurons of the autonomic nervous system.
The posterior rami pass backwards and divide into medial and lateral branches to skin, muscles etc. The anterior rami supply anterior and lateral aspects of the trunk, upper and lower limbs. In the cervical, lumbar and sacral regions, the anterior rami unite near the origins to form large masses of nerves or plexus. They divide and branch to proceed to skin, muscles, joints etc. There are 5 such large plexus. They are the cervical plexus, brachial plexus, lumbar plexus, sacral plexus and coccygeal plexus.