Spinal nerve

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Spinal nerve

The term spinal nerve generally refers to the mixed spinal nerve

Nerve

A nerve is an enclosed, cable-like bundle of Peripheral nervous system axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons....
, which is formed from the dorsal and ventral roots that come out of the spinal cord

Spinal cord

The spinal cord is a long, thin, tubular bundle of neuron and glia that extends from the brain. The brain and spinal cord together make up the central nervous system....
. The spinal nerve is the bit that passes out of the vertebra

Vertebra

A vertebra is an individual bone in the flexible column that defines vertebrate animals. The vertebral column encases and protects the spinal cord, which runs from the base of the cranium down the dorsal side of the animal until reaching the pelvis....
e through the intervertebral foramen. All spinal nerves are part of the peripheral nervous system

Peripheral nervous system

The peripheral nervous system resides or extends outside the central nervous system , which consists of the brain and spinal cord. The main function of the PNS is to connect the CNS to the limbs and organs....
(PNS). There are 31 pairs of spinal nerves in humans.

de the spinal cord, there is grey matter

Grey matter

Grey matter is a major component of the central nervous system, consisting of Neuron Soma , neuropil , glial cells and Capillary. Grey matter contains neural cell bodies, in contrast to white matter, which does not and mostly contains myelinated axon tracts....
, surrounded by white matter

White matter

White matter is one of the three main solid components of the central nervous system. White matter tissue of the freshly cut brain appears white to the naked eye because of being composed largely of lipid....
.

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Encyclopedia

The term spinal nerve generally refers to the mixed spinal nerve

Nerve

Spinal cord

Vertebra

Peripheral nervous system

Formation of the spinal nerves

Inside the spinal cord, there is grey matter

Grey matter

White matter

Dorsal root

In anatomy and neurology, the dorsal root is the afferent nervesomatosensory system 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....
s (one on the left side, and one on the right side) and two ventral roots emerge. (Dorsal means back, ventral means front.) As the body is symmetrical, the same thing happens on both the left and right side of the body. This happens in each vertebra of the spine.

The dorsal roots contain afferent
Afferent nerve

In the nervous system, afferent neurons , carry action potential from receptor s or sense organs toward the central nervous system. This term can also be used to describe relative connections between structures....
sensory
Somatosensory system

The somatosensory system is a diverse sensory system comprising the receptors and processing centres to produce the sensory modality such as touch, temperature perception, proprioception , and nociception ....
axons. The dorsal roots of each side continue outwards, along the way forming a dorsal root ganglion
Dorsal root ganglion

In anatomy and neurology, the dorsal root ganglion is a nodule on a dorsal root that contains cell bodies of neurons in afferent nerve spinal nerves....
(also called a spinal ganglion).

The ventral roots contain efferent
Efferent nerve

In the nervous system, efferent nerves ? otherwise known as motoneuron or effector neurons ? carry action potential away from the central nervous system to effectors such as muscles or glands ....
motor axons. Similar to the dorsal roots, the ventral roots continue out from the spinal column, and meet and mix with their corresponding dorsal nerve root at a point after the ganglion.

At this point, the combination of the dorsal roots and ventral roots is called a mixed spinal wala.

Importance of the spinal nerves

The muscles that one particular spinal root supplies are that nerve's myotome

Myotome

In vertebrate embryonic development, a myotome is a group of tissues formed from somites that develop into the body wall muscle.Each myotome divides into a Dorsum epaxial part and a ventral hypaxial part....
, and the dermatome

Dermatome

Dermatome may refer to:*Dermatome , a surgical instrument used to produce thin slices of skin*Dermatome , an area of skin that is supplied by a single pair of dorsal roots...
s are the areas of sensory innervation on the skin for each spinal nerve.

This is of great importance in the diagnosis

Diagnosis

Diagnosis is the identification of the nature of anything, either by process of elimination or other analytical methods. Diagnosis is used in many different disciplines, with slightly different implementations on the application of logic and experience to determine the cause and effect relationships....
of neurological disorders, as lesions of one or more nerve roots result in typical patterns of neurologic defects (muscle weakness

Muscle weakness

Muscle weakness is a direct term for the inability to exert force with one's muscles to the degree that would be expected given the individual's general physical fitness....
, loss of sensation) that allow localisation of the causeating lesion.

Spinal nerve

Formation of the spinal nerves

Importance of the spinal nerves

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