nerve / nərv/ • n. 1. (in the body) a whitish fiber or bundle of fibers that transmits impulses of sensation to the brain or spinal cord, and impulses from these to the muscles and organs: the optic nerve. 2. (nerves) a person's mental state, in particular the extent to which they are agitated or worried: an amazing journey that tested her nerves to the full. ∎ nervousness or anxiety: his first-night nerves soon disappeared. 3. (often one's nerve) a person's steadiness, courage, and sense of purpose when facing a demanding situation: the army's commanders were beginning to lose their nerve | I got up the nerve to ask Miss Kinnian to have dinner with me. ∎ inf. impudence or audacity: he had the nerve to insult my cooking | she's got nerve wearing that short skirt with those legs. 4. Bot. a prominent unbranched rib in a leaf, esp. in the midrib of the leaf of a moss. • v. (nerve oneself) brace oneself mentally to face a demanding situation: she nerved herself to enter the room. PHRASES: a bundle of nerves inf. someone who is extremely timid or tense. get on someone's nerves inf. irritate or annoy someone. have nerves of steel not be easily upset or frightened. strain every nerve make every possible effort. touch (or hit or strike) a nerve (or a raw nerve) provoke a reaction by referring to a sensitive topic: there are signs that some comments strike a raw nerve. war of nerves a struggle in which opponents try to wear each other down by psychological means.DERIVATIVES: nerved adj. [usu. in comb.] she was still raw-nerved from reliving the past.
The common name for neuron, the basic fiber, or bundles of fibers, that transmit information to and from the muscles, glands, organs, spinal cord, and brain.
Nerves form the network of connections that receive signals, known as sensory input, from the environment and within the body and transmit the body's responses, or instructions for action, to the muscles, organs, and glands. The central nervous system , comprised of the brain and spinal cord, sends information throughout the body over the network of nerves known collectively as the peripheral nervous system . The nerves of the peripheral nervous system are in pairs, with one usually leading to the left side and the other to the right side of the body. There are 12 nerve pairs, called cranial nerves, that connect directly to the brain and control such functions as vision and hearing . Thirty-one nerve pairs are connected directly to the spinal cord, branching out to the rest of the body.
The peripheral nervous system may be further subdivided into the autonomic nervous system , which regulates involuntary functions such as breathing, digestion, beating of the heart, and the somatic nervous system, which controls voluntary functions, such as walking, picking up a pencil, and reading this page. The cells of the central nervous system do not have the ability to regenerate, and are not replaced directly if they are damaged.
See also Neuron