| UN | ulnar nerve; undernourished; unilateral neglect; urea nitrogen; urinary nitrogen |
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| UNCV | ulnar nerve conduction velocity |
| nerve compression syndromes | Repeated or prolonged pressure on a nerve root or peripheral nerve leading to ischemia, the response to which is oedema above and below the source of pressure. If the pressure is not relieved, fibrosis tends to develop. Types of nerve compression syndromes are the neuropathy caused by intervertebral disk herniation, compression of the median nerve in the carpal tunnel, compression of the ulnar nerve in the elbow, and compression of the lateral cutaneous nerve of the thigh in meralgia paresthetica. This is also called pressure neuropathy. (12 Dec 1998) |
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| nerve conduction | The transmission of an impulse along a nerve fibre. (05 Mar 2000) |
| nerve conduction velocity | The rate of impulse conduction in a peripheral nerve or its various component fibres, generally expressed in meters per second. (05 Mar 2000) |
| nerve deafness | Neural deafness, former terms for sensorineural deafness. (05 Mar 2000) |
| nerve decompression | Release of pressure on a nerve trunk by the surgical excision of constricting bands or widening of a bony canal. (05 Mar 2000) |
| nerve degeneration | Loss of functional activity and trophic degeneration of nerve axons and their terminal arborizations following the destruction of their cells of origin or interruption of their continuity with these cells. The pathology is characteristic of neurodegenerative diseases. Often the process of nerve degeneration is studied in research on neuroanatomical localization and correlation of the neurophysiology of neural pathways. (12 Dec 1998) |
| nerve, efferent | A nerve that carries impulses away from the central nervous system. The word efferent comes from the latin ex', away or out + ferre , to bear = to bear out or carry away. (12 Dec 1998) |
| nerve ending | <physiology> A connection between excitable cells, by which an excitation is conveyed from one to the other. 1. Chemical synapse: one in which an action potential causes the exocytosis of neurotransmitter from the presynaptic cell, which diffuses across the synaptic cleft and binds to ligand gated ion channels on the post synaptic cell. These ion channels then affect the resting potential of the post synaptic cell. 2. Electrical synapse: one in which electrical connection is made directly through the cytoplasm, via gap junctions. 3. Rectifying synapse: one in which action potentials can only pass across the synapse in one direction (all chemical and some electrical synapses). 4. Excitatory synapse: one in which the firing of the presynaptic cell increases the probability of firing of the postsynaptic cell. 5. Inhibitory synapse: one in which the firing of the presynaptic cell reduces the probability of firing of the postsynaptic cell. (10 Jan 1998) |
| nerve endings | Specialised terminations of peripheral neurons. Nerve endings include neuroeffector junction(s) by which neurons activate target organs and sensory receptors (see receptors, sensory) which transduce information from the various sensory modalities and send it centrally in the nervous system. Presynaptic nerve endings are presynaptic terminals. (12 Dec 1998) |
| nerve fascicle | A bundle of nerve fibres surrounded by perineurium. (05 Mar 2000) |
| nerve fibre | The axon of a nerve cell, ensheathed by oligodendroglia cells in brain and spinal cord, and by Schwann cells in peripheral nerves. (05 Mar 2000) |
| nerve fibres | Slender processes of neurons, especially the prolonged axons that conduct nerve impulses. (12 Dec 1998) |
| nerve fibres, myelinated | Grayish white nerve fibres whose axons are encased in a myelin sheath which may in turn be enclosed by a neurilemma (a thin membrane spirally enwrapping the myelin layers). (12 Dec 1998) |
| nerve field | The regional distribution of nerve terminals. (05 Mar 2000) |
| nerve force | An obsolete terms denoting the property of nerve tissue to conduct stimuli. (05 Mar 2000) |