| trigeminal ganglion | The semilunar-shaped ganglion containing the cells of origin of most of the sensory fibres of the trigeminal nerve. It is situated within the dural cleft on the cerebral surface of the petrous portion of the temporal bone and gives off the ophthalmic, maxillary, and part of the mandibular nerves. (12 Dec 1998) |
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| trigeminal lemniscus | 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) |
| trigeminal nerve | <anatomy, nerve> The trigeminal nerve is responsible for sensory enervation of the face and motor enervation to muscles of mastication (chewing). There are three divisions of the fifth cranial nerve, ophthalmic, maxillary and mandibular. Lesions of the sensory root to the trigeminal nerve can result in pain or loss of sensation in the face. Lesion of the motor root result in deviation of the jaw toward the paralysed side and difficulty chewing. Synonym: cranial nerve V. (27 Sep 1997) |
| trigeminal neuralgia | <neurology> A disorder of trigeminal nerve (cranial nerve V) dysfunction. Synonym: tic douloureux. Characterised by excruciating paroxysms of pain in the lips, gums, cheek or chin, and, very rarely, in the distribution of the eye (ophthalmic division of the trigeminal nerve). (27 Sep 1997) |
| trigeminal nuclei | Nuclei of the trigeminal nerve situated in the brainstem. They include the nucleus of the spinal trigeminal tract (trigeminal nucleus, spinal), the principal sensory nucleus, the mesencephalic nucleus, and the motor nucleus. (12 Dec 1998) |
| trigeminal nucleus, spinal | Nucleus of the spinal tract of the trigeminal nerve. It is divided cytoarchitectonically into three parts: oralis, caudalis (trigeminal caudal nucleus), and interpolaris. (12 Dec 1998) |
| trigeminal pulse | A pulse in which the beats occur in trios, a pause following every third beat. Synonym: pulsus trigeminus. (05 Mar 2000) |
| trigeminal rhizotomy | Division or section of a sensory root of the fifth cranial nerve, accomplished through a subtemporal (Frazier-Spiller operation), suboccipital (Dandy operation), or transtentorial approach. Synonym: retrogasserian neurectomy, retrogasserian neurotomy. (05 Mar 2000) |
| trigeminal rhythm | A cardiac arrhythmia in which the beats are grouped in trios, usually composed of a sinus beat followed by two extrasystoles. Synonym: trigeminy. (05 Mar 2000) |
| trigeminal system | <neurology> Neurons associated with the fifth or trigeminal nerve, the largest cranial nerve. The trigeminal system provides sensory innervation to the face and mucous membrane of the oral cavity, along with motor innervation to the muscles of mastication. It is called trigeminal because it has three major peripheral branches, the opthalmic, the maxillary and the mandibular nerves. (18 Nov 1997) |
| trigeminal tractotomy | Division of the descending fibres of the trigeminal tract in the medulla. Synonym: intramedullary tractotomy, Sjoqvist tractotomy. (05 Mar 2000) |