The lateral spinothalamic tract
(or lateral spinothalamic fasciculus
) is a bundle of sensory axons ascending through the white matter of the spinal cord, carrying sensory information to the brain. It carries pain and temperature sensory information to the thalamus
of the brain. It is composed primarily of slow-conducting, sparsely-myelinated Aδ axons and slow-conducting, unmyelinated C axons. These are secondary sensory neurons which have already synapsed with the primary sensory neurons of the peripheral nervous system in the dorsal horn of the spinal grey matter.
Together with the anterior, or ventral spinothalamic tract, the lateral spinothalamic tract is sometimes termed the secondary sensory fasciculus or spinal lemniscus.
The neurons of the lateral spinothalamic tract originate in the dorsal horn and immediately decussate in the anterior white commissure
to the contralateral side of the spine. The axons pass through the lateral funiculus
, then ascend the length of the spine on the medial side of the ventral spinocerebellar fasciculus
. On reaching the medulla oblongata
they continue in the formatio reticularis
near the median fillet
and synapse in the ventro-lateral region of the thalamus
with tertiary sensory neurons.
The fibres conduct impulses of pain
. Aδ fibres conduct immediate, sharp pain. C fibres conduct dull, burning pain.