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A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. [1] [2] These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. [1]
It does not run the full length of the vertebral column in adults. It is made of 31 segments from which branch one pair of sensory nerve roots and one pair of motor nerve roots. The nerve roots then merge into bilaterally symmetrical pairs of spinal nerves. The peripheral nervous system is made up of these spinal roots, nerves, and ganglia.
These nerves control the functions of the rest of the body. In humans, there are 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. These nerve roots are named according to the spinal vertebrata which they are adjacent to.
A mixed nerve is any nerve that contains both sensory and motor nerve fibers. [ 1 ] [ 2 ] All 31 pairs of spinal nerves are mixed nerves. [ 3 ] Four of the twelve cranial nerves – V , VII , IX and X are mixed nerves.
[5] 31 pairs of gray rami communicantes exit the sympathetic trunk to join the 31 pairs of spinal nerves and travel to targets such as sweat glands, hair follicles, and blood vessels. [1] Some fibers, such as those in the cardiac nerves that innervate the heart, reach the target organ directly, without first joining a gray ramus communicans.
The spinal nerves are arranged into 31 pairs according to the regions of the spinal cord. To be more precise, there are eight pairs of cervical nerves (C1–C8), twelve pairs of thoracic nerves (T1–T12), five pairs of lumbar nerves (L1–L5), five pairs of sacral nerves (S1–S5), and one pair of coccygeal nerves. Peripheral nerves are ...
It is an essential connection between the body and the brain as well as between the two. The spinal cord has a diameter of 1 to 1.5 cm and a length of 40 to 50 cm. On either side, two successive rows of nerve roots appear. Thirty-one pairs of spinal nerves are formed by the distal union of these nerve roots.
Spinal nerve roots: the initial or proximal segment of one of the 31 pairs of spinal nerves leaving the central nervous system from the spinal cord. Each spinal nerve is a mixed nerve formed by the union of a sensory dorsal root and a motor ventral root, [1] meaning that there are 62 dorsal/ventral root pairs, and therefore 124 nerve roots in ...