nerve


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Related to nerve: sciatic nerve, nerve pain

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 ?
On the basis of these findings, intermediate nerve schwannoma was diagnosed.
Following surgery, the patient presented with temporary partial facial nerve palsy (House-Blackmann, grade 3) and taste disorder.
The type of nerve locator used for the procedure was supplied by Fischer and Paykel with model name "Innervators 232".
The nerve blocks were performed as per the following procedure.
Table-II: Relation of Recurrent Laryngeal Nerve with Inferior Thyroid Artery considering two sides together for N = 100.
The patient was prepared for operative exploration that revealed complete transection and avulsion of the common peroneal nerve at the level of the fibular head and that of tibial nerve in the middle one-third of the calf [Figure 2].
Age of the patient, angulation and depth of impacted tooth, presence of overlying ramus bone, skill of surgeon and surgical approach used are certain factors which increase the chances of lingual nerve injury during removal of third molars.6
The inclusion criteria are as follows: (1) type of publication: original studies including prospective studies, retrospective studies, and bidirectional studies were included; (2) the study participants were patients subjected to CC7 nerve transfer; and (3) the publication reported objective performance indexes for ipsilateral exercise intensity or muscle strength or other indexes of sensory recovery.
The tibial nerve can be subjected to stretch during the lower limb movements or different limb positions; specially, ankle joint dorsiflexion and inversion of the foot.
The hypoglossal nerve is the twelfth cranial nerve, and is a pure motor nerve that is involved in the movements of the tongue and infrahyoid muscles.
This market is witnessing a rapid growth due to increasing geriatric population, increasing incidence of nerve injuries and neurological disorders, favourable reimbursement policies, and increased government funding.
The role of non-invasive imaging techniques, including ultrasonography (USG) and magnetic resonance imaging (MRI) is under exploration and can serve as an important tool to identify both silent and active nerve involvement, thereby preventing deformity and disability.