A sensory nerve, or afferent nerve, is a general anatomic term for a

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

which contains predominantly somatic

afferent nerve fiber Afferent nerve fibers are the axons (nerve fibers) carried by a sensory nerve that relay sensory information from sensory receptors to regions of the brain. Afferent projections ''arrive'' at a particular brain region. Efferent nerve fiber ...

s. Afferent nerve fibers in a sensory nerve carry sensory information toward the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

(CNS) from different sensory receptors of

sensory neuron Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The ...

s in the

peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brai ...

. A

motor nerve A motor nerve is a nerve that transmits motor signals from the central nervous system (CNS) to the muscles of the body. This is different from the motor neuron, which includes a cell body and branching of dendrites, while the nerve is made up of ...

carries information from the CNS to the PNS, and both types of nerve are called peripheral nerves. Afferent nerve fibers link the

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 fibers from the

motor neuron A motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirect ...

s (that travel from the CNS to the PNS), in mixed nerves. Stimuli cause

nerve impulse An action potential 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 types of animal cells, c ...

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 of the spinal cord, and motor commands carried by the efferent fibers leave the cord at the

ventral roots In anatomy and neurology, the ventral root of spinal nerve, anterior root, or motor root is the efferent motor root of a spinal nerve. At its distal end, the ventral root joins with the dorsal root The dorsal root of spinal nerve (or posterio ...

. The dorsal and some of the ventral fibers join as

spinal nerve 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. These are grouped into the ...

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, 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 decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may ...

or other serious conditions. The lack of detection of pain and other sensations is a particularly large problem for those with

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

, which contributes to the rate of lower

limb amputation Amputation is the removal of a limb by trauma, medical illness, or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on ind ...

s 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