This diagram illustrates the spinothalamic tract
(also known as the anterolateral system/ventrolateral system). The spinothalamic tract is one of the ascending sensory tracts
which conveys sensory information from the periphery to the central processing systems. There are three main ascending (afferent) pathways which convey sensory information:
- Dorsal column medial lemniscus system
- Spinocerebellar tracts
- Spinothalamic tracts (anterolateral system)
The spinothalamic tract is responsible for conveying the modalities of crude touch
. The tract is comprised of a three neurone sequence, which terminates in the somatosensory cortex of the postcentral gyrus:
- First order neurone: information carried from peripheral sensory receptors to spinal cord via pseudounipolar neurones. Axons ascend 1-2 vertebral levels and synapse with second order neurones in the substantia gelatinosa.
- Second order neurones: immediately decussate (cross over to the other side) via the anterior white commissure, and ascend to the medulla of the brainstem and then to the thalamus where they synapse with third order neurones.
- Third order neurones: project to the primary somatosensory cortex
The anterior spinothalamic tract conveys crude touch. The lateral spinothalamic tract conveys pain and temperature.