nerve

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nerve:

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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Nerve

 

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.

D. A. SAKHAROV

nerve

[nərv]
(neuroscience)
A bundle of nerve fibers or processes held together by connective tissue.

nervure

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.

nerve

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 ?
And Frostig said that a good massage, listening to a song or otherwise stimulating the right nerve endings might work better.
The parallel growth patterns of the touch and visual nerve endings suggest that specialized sensory systems share basic features of development, says Catania.
Blood pressure and heart rate jump when a person stands up because the sympathetic nervous system--which controls some involuntary body functions--directs nerve endings in the heart to release norepinephrine.
"It is only when we shift focus away from the nerve endings associated with normal skin sensation that we can appreciate the sensation hidden in the background," Rice added.
If you have the cold sore virus, it will sit in nerve endings and appear if you are run down, have a cold or damage the skin in that area.
Compared with 11 untreated counterparts, 8 rats treated with IGF-I had only 14 percent as many swollen nerve endings among nerve cells in the abdomen.
Each of the two olfactory nerves detects smells by means of hair-like receptors (nerve endings specialised in detecting smells) in the lining of the roof of the nasal cavity.
Yosi Shacham-Diamand of TAU's Department of Engineering, along with a team of European Union scientists, successfully wired the state-of-the-art artificial hand to existing nerve endings in the stump of a severed arm.
Meanwhile, a research team led by scientists at the University of California, San Francisco finds that gabapentin also works better than a placebo in counteracting pain from shingles, a viral disease that attacks nerve endings.
Partner Phillip Wells, 54, said: "We now know why the pain was so intense - the maggot was having a chew on her nerve endings."
My GP says it's due to nerve endings but pain killers don't really help.
The gel works by blocking the nerve endings in the nasal passage, reducing inflammation and halting the onset of symptoms.