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A sensory nerve, or afferent nerve, is a general anatomic term for a
nerve A nerve is an enclosed, cable-like bundle of fibers (called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, ...

nerve
which contains predominantly
somatic Somatic may refer to: * Somatic (biology), referring to the cells of the body in contrast to the germ line cells ** Somatic cell, a non-gametic cell in a multicellular organism * Somatic nervous system, the portion of the vertebrate nervous syste ...
afferent nerve fiber Afferent nerve fibers refer to axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences Despite the various English dialects Dialect The term dialect (from Latin , , from th ...
s. Afferent nerve fibers in a sensory nerve carry
sensory information A sense is a biological system A biological system is a complex biological network, network which connects several biologically relevant entities. Biological organization spans several scales and are determined based different structures dependi ...
toward the
central nervous system The central nervous system (CNS) is the part of the nervous system In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecu ...

central nervous system
(CNS) from different
sensory receptors Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of Stimulus (physiology), stimulus, via their Receptor (biochemistry), receptors, into action potentials or graded potentials. This ...
of
sensory neuron Sensory neurons, also known as afferent neurons, are neuron A neuron or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology), cell that communicates with other cells via specialized connections called sy ...
s in the
peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, ...
. A
motor nerve A motor nerve is a nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, s ...
carries information from the CNS to the PNS, and both types of nerve are called peripheral nerves. Afferent nerve fibers link the
sensory neuron Sensory neurons, also known as afferent neurons, are neuron A neuron or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology), cell that communicates with other cells via specialized connections called sy ...
s throughout the body, in pathways to the relevant processing circuits in the central nervous system. Afferent nerve fibers are often paired with
efferent nerve fiber Efferent nerve fibers refer to axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, slender projection of a ne ...
s from the
motor neuron A motor neuron (or motoneuron or efferent neuron) is a whose is located in the , or the , and whose (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly s and s. There are ...
s (that travel from the CNS to the PNS), in
mixed nerves
mixed nerves
. Stimuli cause
nerve impulse In physiology, an action potential (AP) occurs when the membrane potential of a specific cell location rapidly rises and falls: this depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several type ...

nerve impulse
s in the receptors and alter the potentials, which is known as sensory transduction.


Spinal cord entry

Afferent nerve fibers leave the sensory neuron from the
dorsal root ganglia A dorsal root ganglion (or spinal ganglion; also known as a posterior root ganglion) is a cluster of neurons A neuron or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synap ...
of the spinal cord, and motor commands carried by the efferent fibers leave the cord at the ventral roots. The dorsal and some of the ventral fibers join as
spinal nerve A spinal nerve is a , which carries motor, sensory, and autonomic signals between the and the body. In the there are 31 pairs of spinal nerves, one on each side of the . These are grouped into the corresponding , , , and regions of the spine. ...

spinal nerve
s or mixed nerves.


Nerve damage

Damage to the sensory nerve causes a wide range of symptoms because of the number of functions performed by the nerve. Traumatic injuries and other damages to the sensory nerves may lead to
peripheral neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland or org ...
, with problems such as reduced position sense causing poorer coordination and balance, in addition to reduced sensitivity to temperature change and pain, leading to further problems. The ability to feel pain or changes in temperature can be affected by damage to the fibers in the sensory nerve. This can cause a failure to notice injuries such as a cut or that a wound is becoming infected. There may also be a lack of detection of
heart attacks A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...
or other serious conditions. The lack of detection of pain and other sensations is a particularly large problem for those with
diabetes Diabetes mellitus, commonly known as just diabetes, is a group of metabolic disorders characterized by a hyperglycemia, high blood sugar level over a prolonged period of time. Symptoms often include frequent urination, Polydipsia, increased th ...

diabetes
, which contributes to the rate of lower limb amputations among this population. Overall, the poor sensation and detection may lead to changes in skin, hair, joint, and bone damage over the years for many people.


References


External links

*
Peripheral Neuropathy
from the US NIH
Neuropathy: Causes, Symptoms and Treatments
from ''Medical News Today''
Peripheral Neuropathy
at the Mayo Clinic {{Authority control Sensory systems