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nerve ending

The termination of a nerve fiber (axon or dendrite) in a peripheral structure. It may be sensory (receptor) or motor (effector). Sensory endings can be nonencapsulated, e.g., free nerve endings, peritrichal endings, or tactile corpuscles of Merkel, or they can be encapsulated, e.g., end-bulbs of Krause, Meissner corpuscles, Vater-Pacini corpuscles, or neuromuscular and neurotendinous spindles.

nerve entrapment syndrome

Compression of a nerve or nerves resulting in nerve damage. This may cause anesthesia or pain if a sensory nerve is affected and paralysis if a motor nerve is involved. The compression may be due to physical pressure on the nerve, i.e., sleeping in a position in which a nerve is pressed upon by surrounding tissue, or to swelling of tissue in a compartment through which the nerve passes. SEE: carpal tunnel syndrome.

nerve fiber

1. An axon. Nerve fibers are identified by intrinsic characteristics (such as diameter, presence of myelin, or neurotransmitter type) or by extrinsic characteristics, such as whether they conduct sensory or motor information. SEE: axon.

Nerve fiber, or simply fiber is more often used in anatomical descriptions, and fiber tract is more commonly used than axon tract. Axon is more commonly used in histological descriptions. 2. An axon or a small group of axons bundled together by glia or Schwann cells. 3. In informal usage, a small peripheral nerve.

myelinated n.f. A nerve fiber with a myelin sheath. SYN: medullated nerve fiber.

nerve gas

SEE: under gas.


(nĕrv′spar″ing) Pert. to surgery that does not remove or injure nerves adjacent to or within the organ being removed from the body. In prostatectomy, a nerve-sparing procedure preserves the parasympathetic and sympathetic nerves that control penile erection and ejaculation.

nerve supply of ear

External: The branches of the facial, vagus, and mandibular nerves and the nerves from the cervical plexus. Middle: The tympanic plexus and the branches of the mandibular, vagus, and facial nerves. Internal: The vestibulocochlear nerve (eighth cranial).

nerve tissue

SEE: under tissue.


(ner′vyōs) [Sp. nervios, nerves] Ataque de nervios.


(nĕr′vŭs) [L. nervosus, sinewy, vigorous, nervous] 1. Anxious. 2. Excitable or easily irritated. 3. Pert. to nerves or neurons.

nervous breakdown

A colloquial term for any incapacitating mental illness, esp. one having acute onset and interfering with normal function, thought, or behavior.


Anxiety; tension.

nervous system

One of an organism’s regulatory systems, made of millions of neurons (that transmit ...

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