A sensory nerve, or afferent nerve, is a

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...

that contains exclusively

afferent nerve fiber Afferent nerve fibers are axons (nerve fibers) of sensory neurons that carry sensory information from sensory receptors to the central nervous system. Many afferent projections ''arrive'' at a particular brain region. In the peripheral nerv ...

s. Nerves containing also motor fibers are called mixed. 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, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

(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 receptor potentials. This process is called sensory transduc ...

s in the

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

(PNS). A

motor nerve A motor nerve, or efferent nerve, is a nerve that contains exclusively efferent nerve fibers and transmits motor signals from the central nervous system (CNS) to the effector organs (muscles and glands), as opposed to sensory nerves, which transf ...

carries information from the CNS to the PNS. 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 fiber Efferent nerve fibers are axons (nerve fibers) of efferent neurons that exit a particular region. These terms have a slightly different meaning in the context of the peripheral nervous system (PNS) and central nervous system (CNS). The efferen ...

s from the

motor neuron A motor neuron (or motoneuron), also known as 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 o ...

s (that travel from the CNS to the PNS), in

mixed nerve A mixed nerve is any nerve that contains both sensory ( afferent) and motor ( efferent) nerve fibers. All 31 pairs of spinal nerves are mixed nerves. Four of the twelve cranial nerves – V, VII, IX and X are mixed nerves. Examples Spinal n ...

s. Stimuli cause

nerve impulse An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly ri ...

s in the receptors and alter the potentials, which is known as

sensory transduction In physiology, transduction is the translation of arriving stimulus into an action potential by a sensory receptor. It begins when stimulus changes the membrane potential of a sensory receptor. A sensory receptor converts the energy in a stimulu ...

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. The dorsal and some of the ventral fibers join as

spinal nerve A spinal nerve is a mixed nerve, which carries Motor neuron, motor, Sensory neuron, sensory, and Autonomic nervous system, autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each s ...

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, refers to damage or disease affecting the nerves. Damage to nerves may impair sensation, movement, gland function, and/or organ function depending on which nerve fibers are affected. Neuropa ...

, 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 in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom is retr ...

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 diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...

, 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

Spinal cord entry

Nerve damage

See also

References

External links