| lemniscus spinalis | A large ascending fibre bundle in the ventral half of the lateral funiculus of the spinal cord, arising from cells in the posterior horn at all levels of the cord, which cross within their segments of origin in the white commissure. In their contralateral ascent, the bundle is intermingled with numerous intersegmental fibres. The spinothalamic tract continues from the spinal cord into the brainstem, occupying a ventrolateral position and issuing numerous fibres to the rhombencephalic and mesencephalic reticular formation, to the lateral part of the central gray substance of the mesencephalon, and to the deep and intermediate layers of the superior colliculus; the relatively few fibres (10 to 20%) that remain form the true spinothalamic tract which enters the diencephalon and ends in the nucleus ventralis posterior (caudal part) and intralaminar nuclei of the thalamus. In its ascent in the spinal cord the tract is composed of a dorsal part, the lateral spinothalamic tract, which conveys impulses associated with pain and temperature sensation, and a more ventral part, the anterior spinsothalamic tract, involved in tactile sensation. Synonym: lemniscus spinalis, spinal lemniscus, tractus spinothalamicus. (05 Mar 2000) |
|---|---|
| lemniscus trigeminalis | Collective term denoting the fibres ascending from the sensory nucleus of the trigeminus; one such fibre system originates from the main sensory nucleus, largely decussates, and ascends as the ventral trigeminal lemniscus to join the medial lemniscus with which it enters the ventral posterior nucleus of thalamus, terminating in the mediodorsal region of that nucleus; a second, uncrossed, fibre group follows an ascending course through central parts of the mesencephalic tegmentum ("dorsal trigeminal lemniscus"). The trigeminal lemniscus conveys tactile, pain, and temperature impulses from the skin of the face, the mucous membranes of the nasal and oral cavities, and the eye, as well as proprioceptive information from the facial and masticatory muscles. Synonym: lemniscus trigeminalis. (05 Mar 2000) |
| lemon | 1. <botany> An oval or roundish fruit resembling the orange, and containing a pulp usually intensely acid. It is produced by a tropical tree of the genus Citrus,the common fruit known in commerce being that of the species C. Limonum or C. Medica (var. Limonum). There are many varieties of the fruit, some of which are sweet. 2. The tree which bears lemons; the lemon tree. <botany> Lemon grass, a white crystalline substance, inappropriately named, as it consists of an acid potassium oxalate and contains no citric acid, which is the characteristic acid of lemon; called also salis of sorrel. It is used in removing ink stains. See Oxalic acid, under Oxalic. Origin: F. Limon, Per. Limn; cf. Ar.laimn, Sp. Limon, It. Limone. Cf. Lime a fruit. Source: Websters Dictionary (01 Mar 1998) |
| lemon sign | <radiology> Concave frontal bones, suggests neural tube defect also: banana sign (12 Dec 1998) |
| lemon yellow | A fine yellow powder used in paints and dyes. Synonym: lead chromate, Leipzig yellow, lemon yellow, Paris yellow. (05 Mar 2000) |
| lemur | <zoology> One of a family (Lemuridae) of nocturnal mammals allied to the monkeys, but of small size, and having a sharp and foxlike muzzle, and large eyes. They feed upon birds, insects, and fruit, and are mostly natives of Madagascar and the neighboring islands, one genus (Galago) occurring in Africa. The slow lemur or kukang of the East Indies is Nycticebus tardigradus. See Galago, Indris, and Colugo. Origin: L, a ghost, specter. So called on account of its habit of going abroad by night. Source: Websters Dictionary (01 Mar 1998) |
| lemurid | <zoology> Same as Lemuroid. Source: Websters Dictionary (01 Mar 1998) |
| lemuridae | A family of the order primates, suborder strepsirhini (prosimii), containing four genera which inhabit madagascar and the comoro island. most of the lemurs prefer wooded areas. The four genera are hapalemur, lemur, lepilemur, and varecia. (12 Dec 1998) |
| lemurine | <zoology> Lemuroid. Source: Websters Dictionary (01 Mar 1998) |
| lemuroid | <zoology> Like or pertaining to the lemurs or the Lemuroidea. One of the Lemuroidea. Origin: Lemur. Source: Websters Dictionary (01 Mar 1998) |
| lemuroidea | <zoology> A suborder of primates, including the lemurs, the aye-aye, and allied species. Alternative forms: Lemuroida. Origin: NL. See Lemur, and -oid. Source: Websters Dictionary (01 Mar 1998) |