Anterior spinothalamic tract
Tractus spinothalamicus anterior
An ascending pathway in the anterior funiculus of the spinal cord that carries crude touch and pressure from the opposite side to the thalamus.
At a glance
- English
- Anterior spinothalamic tract
- Latin (TA2)
- Tractus spinothalamicus anterior
- System
- Brain and spinal cord
- Region
- Whole body
- Side
- Single, on the midline
About the anterior spinothalamic tract
The anterior (ventral) spinothalamic tract is the smaller of the two spinothalamic pathways. It runs up near the surface of the anterior funiculus, close to where the anterior roots leave, and its fibres mix with those of the vestibulospinal tract. Together with the lateral spinothalamic tract it is sometimes grouped as the spinal lemniscus or anterolateral system. Older authors regarded it as uncertain, and many modern accounts treat both tracts as one anterolateral pathway.
Three neurons carry the signal. The first is a sensory cell in a dorsal root ganglion, with a large Aβ fibre from receptors in the skin. On entering the cord the central process may travel up or down a segment or two in the posterolateral (Lissauer's) tract before ending in the posterior horn, chiefly in the nucleus proprius. The second-order cell sends its axon across the midline in the anterior white commissure, and the axon then climbs in the opposite anterior funiculus.
The fibres pass through the brainstem and end in the ventral posterolateral nucleus of the thalamus. From there third-order fibres run through the internal capsule to the primary somatosensory cortex of the postcentral gyrus.
The tract conveys crude, poorly localised touch and pressure, sometimes called protopathic touch. Fine, discriminating touch, vibration and position sense take another route, the posterior column and medial lemniscus pathway, which stays on the same side in the cord and crosses in the medulla. Because touch reaches the brain by two separate paths, a lesion of one half of the cord rarely abolishes touch completely, which is a useful point when reading the pattern of sensory loss after spinal injury.
Function and supply
- Function
- Carries crude touch and pressure from the opposite side of the body to the thalamus and onward to the somatosensory cortex.
- Blood supply
- Lies in the territory of the anterior spinal artery.
Anthromica
See the anterior spinothalamic tract where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
