A
big 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 stuff of the mesencephalon, and to the
deep and
intermediate layers of the superior colliculus; the relatively
little fibres (10 to 20%) that stay
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.