| preganglionic | Situated proximal to or preceding a ganglion; referring specifically to the preganglionic motor neurons of the autonomic nervous system (located in the spinal cord and brainstem) and the preganglionic, myelinated nerve fibres by which they are connected to the autonomic ganglia. (05 Mar 2000) |
|---|---|
| preganglionic fibres | A fibre whose cell body is located in an autonomic nucleus in the spinal cord or brain stem and whose axon terminates in an autonomic (motor) ganglion; found in nerves conveying sympathetic or parasympathetic fibres. (05 Mar 2000) |
| preganglionic motor neuron | See: motor neuron. (05 Mar 2000) |
| autonomic fibres, preganglionic | Nerve fibres which project from the central nervous system to autonomic ganglia. In the sympathetic division most preganglionic fibres originate with neurons in the intermediolateral column of the spinal cord, exit via ventral roots from upper thoracic through lower lumbar segments, and project to the paravertebral ganglia; there they either terminate in synapses or continue through the splanchnic nerves to the prevertebral ganglia. In the parasympathetic division the fibres originate in neurons of the brainstem and sacral spinal cord. In both divisions the principal transmitter is acetylcholine but peptide cotransmitters may also be released. (12 Dec 1998) |
|---|