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Related to afferent nerve: afferent neuron, Afferent fibers, afferent pathway


see nervous systemnervous system,
network of specialized tissue that controls actions and reactions of the body and its adjustment to the environment. Virtually all members of the animal kingdom have at least a rudimentary nervous system.
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the cordlike association of nerve tissues that links the brain and nerve ganglia by innervation to the other organs and tissues of the body.

A nerve primarily consists of nerve fibers. In vertebrates many nerves converge to form a bundle that is surrounded by a connective tissue sheath, the perineurium; the thin interstitial layers of connective tissue that separate the individual fibers deep within the bundle constitute the endoneurium. Finally, the entire nerve trunk, comprising several bundles, is covered by an additional sheath, the epineurium.

Nerves can be sensory (also called afferent or centripetal) or motor (also called efferent or centrifugal). Some nerves, for example, those innervating the skeletal muscles, mainly include myelinated, or medullated, fibers; others, for example, the sympathetic nerves, largely consist of unmyelinated, or unmedullated, fibers.

In reptiles, birds, mammals, and man 12 pairs of cranial nerves branch from the brain: the olfactory (cranial nerve I), the optic (cranial nerve II), the oculomotor (cranial nerve III), the trochlear (cranial nerve IV), the trigeminal (cranial nerve V), the abducent (cranial nerve VI), the facial (cranial nerve VII), the acoustic (cranial nerve VIII), the glossopharyngeal (cranial nerve IX), the vagus (cranial nerve X), the accessory (cranial nerve XI), and the hypoglossal (cranial nerve XII). Only the first ten pairs are present in fish and amphibians.

In man there are 31 pairs of spinal nerves: eight cervical, 12 thoracic, five lumbar, five sacral, and one coccygeal. Each pair innervates the effectors and receptors of a certain part of the body. The spinal nerves branch from the spinal cord into two roots—the posterior, or sensory, and the anterior, or motor. Both roots then combine to form a common trunk that consists of both sensory and motor fibers.

Several adjacent nerves can be combined into nerve plexuses, where an exchange of fibers between different nerves can take place. Three large plexuses are distinguished: the cervical, the brachial, and the lumbosacral. Each nerve plexus is the origin of several pairs of nerves; for example, the sacral portion of the lumbosacral plexus gives rise to the sciatic nerves.

Nerves that originate in the ganglia, trunks, and plexuses of the autonomic nervous system constitute a specific group. The optic nerve is remarkable for its large number of fibers; there are more than 1 million in the human optic nerve. Usually, however, there are 103 -104 fibers in a nerve. In invertebrates certain nerves are known to consist of only a few fibers. The peripheral nervous system in animals and man consists of aggregations of nerves.



A bundle of nerve fibers or processes held together by connective tissue.


Any one of the ribs of a groined vault, but esp. a rib which forms one of the sides of a compartment of the groining.


1. any of the cordlike bundles of fibres that conduct sensory or motor impulses between the brain or spinal cord and another part of the body
2. a large vein in a leaf
3. any of the veins of an insect's wing
References in periodicals archive ?
These data may indicate that the afferent nerve system of the tactile sensation was preserved even though thermal sensation was impaired.
An ampullary organ consisting of a 3-cm length of canal with ampulla, innervated by a 5-mm length of afferent nerve, was excised from live, anesthetized skates (Raja erinacea and Raja ocellata).
We now know that inserting needles into the skin and manipulating them or using high- or low-intensity electrical stimulation results in a number of physiologic events: stimulation of small myelinated type II and III afferent nerve fibers; release of beta-endorphins and neurotransmitters such as serotonin and substance P; and activation of the dorsal horn nuclei at the spinal cord level, the brain stem level, and the hypothalamic-pituitary level.
In animal models, extracellular cGMP inhibited afferent nerve firing and positively affected markers of abdominal pain, while intracellular cGMP led to activation of anion channels which stimulated anion and fluid section into the intestine, leading to accelerated intestinal transit.
23,24] In addition, the peripheral terminals of primary afferent nerves innervating somatic tissues also express NMDA receptors.
PGE2 stimulates the release of tachykinins, which stimulate neurokinin receptors on afferent nerves and the detrusor smooth muscle and as a result promote detrusor contraction (Andersson & Hedlund, 2002; Verhamme et al.
As the diagram 1 show, implementation of fatigue protocol on proximal area of lower parts (knee extensors) has had more influence on decrease of the subjects' access distance in Star test, which may probably be explained as: knee area fatigue just brings change and fall of the function of muscles and afferent nerves of this area.
The spinal afferent nerves supplying the abdominal wall lie in the neurofascial plane between the transversus abdominis and internal oblique muscles prior to reaching the anteriorly situated rectus abdominis muscle.
Massive vascular effects on efferent nerves can be expected when it is taken into account that the abnormal sensorial and vegetative input coming from the incisive papilla trauma can excite potent vasodilator-mediated afferent nerves (Ertsey et al.
They cover development and plasticity, vagal sensory ganglion neurons, vagal sensory nerve terminals, connections in the central nervous system, organ-specific afferent nerves, and vagal reflexes and sensation.
Consequently, we previously proposed a mechanism of increased sensitivity of the afferent nerves in patients with airway symptoms induced by scents and chemicals and suggested using the term "sensory hyperreactivity" (SHR; Millqvist et al.