| PNB | p-nitrobiphenyl; perineal needle biopsy; peripheral nerve block; premature nodal beat |
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| PNI | peripheral nerve injury; postnatal infection; prognostic nutritional index |
| PNL | peripheral nerve lesion; polymorphonuclear neutrophilic leukocyte |
| PNM | perinatal mortality; peripheral dysostosis, nasal hypoplasia, and mental retardation [syndrome]; per... |
| PNS | paraneoplastic syndrome; parasympathetic nervous system; partial nonprogressive stroke; peripheral n... |
| nerve block | Interruption of the conduction of impulses in peripheral nerves or nerve trunks by the injection of a local anaesthetic solution. (12 Dec 1998) |
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| nerve block anaesthesia | Conduction anaesthesia in which local anaesthetic solution is injected about nerves, nerve trunks, or nerve plexuses. (05 Mar 2000) |
| nerve cell | An excitable cell specialised for the transmission of electrical signals over long distances. Neurons receive input from sensory cells or other neurons and send output to muscles or other neurons. Neurons with sensory input are called sensory neurons, neurons with muscle outputs are called motoneurons, neurons that connect only with other neurons are called interneurons. Neurons connect with each other via synapses. Neurons can be the longest cells known, a single axon can be several metres in length. Although signals are usually sent via action potentials, some neurons are nonspiking. (18 Nov 1997) |
| nerve cell body | The part of the neuron that includes the nucleus but excludes the processes. (05 Mar 2000) |
| 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) |
| 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) |