nerve

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Related to occipital nerve: lesser occipital nerve, third occipital nerve

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 ?
Often though, we see it manifested after physical insult to the greater or lesser occipital nerve pathways i.
We believe the combination of prolonged immobility and compression of the occipital nerves between the bony superior nuchal ridge and the head rest are the most likely aetiology.
Occipital nerve stimulation for headache: mechanisms and efficacy.
Occipital nerve stimulation (ONS) is achieved by the delivery of asymmetric biphasic electrical pulses via subcutaneous wires attached to the tissue surrounding the occipital nerve, located between the back of the neck and the skull.
Nerves that respond well to freezing include the ilioinguinal nerves, intercostal nerves, and occipital nerves.
It has been proposed that the clinical benefit for temporal placement may be based on coverage of the terminal branches of the trigeminal nerves, along with the communicating branches between the auriculotemporal nerve and the lesser occipital nerve.
A more detailed chapter on occipital nerve stimulation completes this section.
New invasive procedures, such as hypothalamic deep brain stimulation and bilateral occipital nerve stimulation, may help patients with chronic refractory headache.
Doctors also are not sure how the occipital nerve stimulators stop the headaches but they think that the stimulator modifies the abnormal activity.
Perhaps the reason for this can be explained by the greater degree of collateral nerve supply to the angle of the mandible from the lesser occipital nerve posteriorly and from the transverse cutaneous nerve of the neck; both of these nerves derive from the second and third cervical nerves, as does the great auricular nerve.
For reasons that are unclear, greater occipital nerve blocks seem to work well, giving some patients up to 13 days free of cluster headaches, even when their pain (like that of most cluster patients) is not located in the occipital area.
Patients with severe headaches unresponsive to medications or who can't tolerate pain medications may be helped by an occipital nerve bock.