Nerve root
Encyclopedia
A nerve root is the initial segment of a nerve
leaving the central nervous system
. Types include:
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
leaving the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
. Types include:
- A cranial nerveCranial nervesCranial nerves are nerves that emerge directly from the brain, in contrast to spinal nerves, which emerge from segments of the spinal cord. In humans, there are traditionally twelve pairs of cranial nerves...
root, the beginning of one of the twelve pairs leaving the central nervous system from the brain stemBrain stemIn vertebrate anatomy the brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves...
or the highest levels of the spinal cord; - A spinal nerveSpinal nerveThe term spinal nerve generally refers to a mixed spinal nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body...
root, the beginning of one of the thirty-one pairs leaving the central nervous system from the spinal cordSpinal cordThe spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
. Each spinal nerve root consists of the union of a sensory dorsal rootDorsal rootIn anatomy and neurology, the dorsal root is the afferentsensory root of a spinal nerve.At the distal end of the dorsal root is the dorsal root ganglion, which contains the neuron cell bodies of the nerve fibres conveyed by the root.If the dorsal root of a spinal nerve were severed it would lead...
and a motor ventral rootVentral rootIn anatomy and neurology, the ventral root 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....
.