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In anatomy and neurology, the ventral root of spinal nerve, anterior root, or motor root [1] is the efferent motor root of a spinal nerve. At its distal end, the ventral root joins with the dorsal root to form a mixed spinal nerve .
Spinal nerve roots are much more uniform than cranial nerves, one emerging from each level of the spinal column. These roots look extremely similar to one another, and form separate sensory and motor root connections to the central nervous system. Sensory nerves all enter the column as dorsal nerve roots, while motor nerves enter as ventral ...
Branches of the cervical plexus, which include the phrenic nerve, innervate muscles of the neck, the diaphragm, and the skin of the neck and upper chest. The brachial plexus contains ventral rami from spinal nerves C5–T1. This plexus innervates the pectoral girdle and upper limb. The lumbar plexus contains ventral rami from spinal nerves L1–L4.
The dorsal root is the afferent sensory root and carries sensory information to the brain. The ventral root is the efferent motor root and carries motor information from the brain. The spinal nerve emerges from the spinal column through an opening (intervertebral foramen) between adjacent vertebrae.
Nerve rootlets combine to form nerve roots. Likewise, sensory nerve rootlets form off right and left dorsal lateral sulci and form sensory nerve roots. The ventral (motor) and dorsal (sensory) roots combine to form spinal nerves (mixed; motor and sensory), one on each side of the spinal
Ventral root axons join with dorsal root ganglia to form mixed spinal nerves (below). These then merge to form peripheral nerves. Shortly after this spinal nerve forms, it then branches into the dorsal ramus and ventral ramus. Spinal nerves are mixed nerves that carry both sensory and motor information.
The cuneate fasciculus is triangular on transverse section, and lies between the gracile fasciculus and the posterior column, its base corresponding with the surface of the spinal cord. Its fibers, larger than those of the gracile fasciculus, are mostly derived from the same source, viz., the posterior nerve roots.
The general rule of interaction of the nerve fibers in the sympathetic nervous system begins at the spinal cord. Here they arise from the thoracolumbar (T1–L2) regions' lateral horn of grey and emerge via the ventral root. They enter their respective spinal nerve (e.g. T5), and thus enter the white ramus communicans. This myelinated division ...