| parasternal line | A vertical line equidistant from the sternal and midclavicular lines. Synonym: linea parasternalis, costoclavicular line. (05 Mar 2000) |
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| parasternal lymph nodes | A number of small nodes that lie along the course of the internal thoracic vessels; lymph enters these nodes from the anterior intercostal spaces, pericardium, diaphragm, liver and medial mammary gland; the efferent vessels pass upward to join the bronchomediastinal trunk of the same side. Synonym: nodi lymphatici parasternales. (05 Mar 2000) |
| parastichy | <botany> A secondary spiral in phyllotaxy, as one of the evident spirals in a pine cone. Origin: Pref. Para- + Gr. A row. Source: Websters Dictionary (01 Mar 1998) |
| parastriate area | Area of the occipital lobe concerned with vision. (12 Dec 1998) |
| parastriate cortex | See: visual cortex. (05 Mar 2000) |
| Parastrongylus | A genus of parasitic nematodes of the superfamily metastrongyloidea. Two species, angiostrongylus cantonensis and a. Vasorum, infest the lungs of rats and dogs, respectively. A. Cantonensis is transmissible to man where it causes frequently fatal infection of the central nervous system. (12 Dec 1998) |
| parastruma | An obsolete term for a goitrous tumefaction resulting from enlargement of a parathyroid gland. Origin: para-+ L. Struma, a scrofulous tumour (05 Mar 2000) |
| parasympathectomy | The removal or interruption of some part of the parasympathetic nervous system for therapeutic or research purposes. (12 Dec 1998) |
| parasympathetic | Pertaining to a division of the autonomic nervous system. See: autonomic nervous system. (05 Mar 2000) |
| parasympathetic fibres, postganglionic | Nerve fibres which project from parasympathetic ganglia to synapses on target organs. Parasympathetic postganglionic fibres use acetylcholine as transmitter. They may also release peptide cotransmitters. (12 Dec 1998) |
| parasympathetic ganglia | Those ganglia of the autonomic nervous system composed of cholinergic neurons receiving afferent fibres from preganglionic visceral motor neurons in either the brainstem or the middle sacral spinal segments (S2 to S4); on the basis of their location with respect to the organs they innervate, most parasympathetic ganglia, at least outside the head, can be categorised as juxtamural or intramural ganglia. See: autonomic nervous system. (05 Mar 2000) |
| parasympathetic nerve | <anatomy, nerve> One of the nerve's of the parasympathetic nervous system. (05 Mar 2000) |
| parasympathetic nervous system | <anatomy, neurology> One of the two divisions of the vertebrate autonomic nervous sytem. Parasympathetic nerves emerge cranially as pre ganglionic fibres from oculomotor, facial, glossopharyngeal and vagus and from the sacral region of the spinal cord. most neurons are cholinergic and responses are mediated by muscarinic receptors. The parasympathetic system innervates, for example: salivary glands, thoracic and abdominal viscera, bladder and genitalia. Compare:. Sympathetic nervous system. (18 Nov 1997) |
| parasympathetic root of ciliary ganglion | A branch of the oculomotor nerve supplying parasympathetic preganglionic nerve fibres to the ciliary ganglion. Synonym: radix parasympathica ganglii ciliaris, radix oculomotoria ganglii ciliaris, motor root of ciliary ganglion, oculomotor root of ciliary ganglion, radix brevis ganglii ciliaris, short root of ciliary ganglion. (05 Mar 2000) |
| parasympatholytic | Relating to an agent that annuls or antagonises the effects of the parasympathetic nervous system; e.g., atropine. (05 Mar 2000) |