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Related to Nerve terminal: synaptic cleft, Synaptic knob


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 ?
Cysteine catalytic triads are often located within the active sites of many critical nerve terminal enzymes (e.
The data demonstrate that unlike Glial cell-Derived Neurotrophic Factor (GDNF), MANF significantly reduces behavioral deficits, increases dopaminergic (DA) nerve terminal reinnervation of the striatum, and increases dopamine concentrations in the striatum when MANF is administered directly to the substantia nigra (SNc).
At the time when an electrical impulse from one cell reaches a nerve terminal, Syt IV triggers the release of calcium.
A third pattern, damage to neuritic projections, produces a decrement in the membrane/total protein ratio in the nerve terminal region but an increase in areas where reactive sprouting takes place (Kostrzewa and Jacobowitz 1974; Navarro et al.
On the basis of physiologic testing, five patients in the medical treatment group were switched to the surgical treatment because of a previously unidentified sphincter defect noted on endoanal ultrasound, three patients in the surgical group were switched to the medical treatment group because of normal endoanal ultrasound findings, and the surgical treatment of choice was changed in one patient because of normal endoanal ultrasound findings and pudendal nerve terminal motor latency identified by electromyography, Dr.
For example, kinesin ferries neurotransmitters down the extensions of nerve cells, whereas dynein, another motor protein, shuttles cargo in the opposite direction, from the nerve terminal bac| to the center of the cell, says Ronald D Vale, a cell biologist at the University of California, San Francisco.
In Parkinson's disease, the nigro-striatal network (substantia nigra - striatum) is compromised due to the degeneration of dopaminergic neurons in the substantia nigra, which results in dopaminergic nerve terminal retraction from the striatum towards the substantia nigra.
No changes in anal manometry, sphincter integrity upon endoanal ultrasound, or pudendal nerve terminal motor length were noted.
Because HC-3 binding is responsive to cholinergic nerve impulse activity, whereas CHAT is a static marker for nerve terminals, the ratio of HC-3 binding to ChAT activity represents an index of activity per nerve terminal (Aubert et al.
Neuropathic pain responds to drugs that produce a blockade of neuronal sodium channels, inhibiting nerve terminal release of dopamine, [gamma]-aminobutyric acid, and glutamate.