The trigeminal lemniscus, also called the trigeminothalamic tract, is composed of the
ventral trigeminal tract, and the
dorsal trigeminal tract –
nerve tract
A nerve tract is a bundle of nerve fibers (axons) connecting nuclei of the central nervous system. In the peripheral nervous system this is known as a nerve, and has associated connective tissue. The main nerve tracts in the central nervous syste ...
s that convey tactile, pain, and temperature impulses from the skin of the face, the
mucous membrane
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It i ...
s of the nasal and oral cavities, and the eye, as well as proprioceptive information from the facial and
masticatory muscles
There are four classical muscles of mastication. During mastication, three muscles of mastication (''musculi masticatorii'') are responsible for adduction of the jaw, and one (the lateral pterygoid) helps to abduct it. All four move the jaw lat ...
.
The trigeminal lemniscus is composed of second order neuronal axons in the brainstem. It carries sensory information from the
trigeminal system to the
ventral posteromedial (VPM) nucleus of the thalamus.
This tract was historically considered a cephalic division of the
medial lemniscus due to the close proximity of the two ascending tracts. Like the medial lemniscus in the
dorsal column-medial lemniscus pathway
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal co ...
(DCML), that carries mechanosensory information from part of the head and the rest of the body, the trigeminal lemniscus carries mechanosensory information from the face.
However, the trigeminal lemniscus also carries pain and temperature sensations from the contralateral orofacial region, just as the
spinothalamic tract
The spinothalamic tract is a part of the anterolateral system or the ventrolateral system, a sensory pathway to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory ...
carries these sensations from the contralateral body. Thus, the trigeminal lemniscus of the head is functionally analogous to both the DCML tracts and the spinothalamic tract of the body.
Divisions
The trigeminal lemniscus contains two main divisions:
* The
ventral trigeminal tract, consisting of second order neuronal axons from the
Spinal Nucleus of Trigeminal nerve. These fibers cross the midline and ascend to the contralateral thalamus.
* The
dorsal trigeminal tract, consisting of second order neuronal axons from the principal (chief sensory) nucleus. These fibers do not cross the midline, and ascend to the ipsilateral thalamus.
References
Sources
* Anthoney, T. R. (1993). ''Neuroanatomy and the neurologic exam: a thesaurus of synonyms, similar-sounding non-synonyms, and terms of variable meaning''. CRC Press.
* Snell, R. S. (2010). ''Clinical neuroanatomy''. Lippincott Williams & Wilkins.
* Miller MW, Muller SJ. Structure and histogenesis of the principal sensory nucleus of the trigeminal nerve: effects of prenatal exposure to ethanol. J Comp Neurol. 1989;282:570–580
[Frost DO. Development of anomalous retinal projections to nonvisual thalamic nuclei in Syrian hamsters: a quantitative study. J Comp Neurol. 1986;252:95–105]
{{Authority control
Somatosensory system
Central nervous system pathways
Thalamus