Nerve
Spinothalamic tract
Ascending anterolateral pathway for pain, temperature and coarse touch
High-yield
This pathway crosses within the spinal cord. A one-sided anterolateral lesion can therefore reduce pain and temperature sensation on the opposite side, often beginning a few segments below the lesion because entry and crossing are spread over levels.
Overview
Body sensory input first reaches the dorsal horn. Many pain and temperature afferents send short branches up or down before relaying. Projection neurons then cross through the anterior white commissure and ascend mainly in the opposite anterolateral cord toward thalamic and other brain targets.
Reference facts
- Origin
- Dorsal horn projection neurons receiving primary afferent input; many pain and temperature afferents have small myelinated Aδ or unmyelinated C fibers and cell bodies in dorsal root ganglia
- Course
- Primary branches may run briefly in Lissauer's tract before a dorsal-horn relay; crossing projection fibers ascend in the anterolateral cord and brainstem to thalamic nuclei, including the VPL, with onward cortical projections
- Motor
- Transmits sensory information upward rather than motor commands to muscles
- Sensory
- Pain and temperature are prominent lateral components; coarse touch and pressure are associated with anterior components, with overlap between pathways
Mnemonic
Pain and temperature: think lateral anterolateral pathway and an early crossing in the cord.
Clinical correlation
A central cord cavity, or syrinx, can damage crossing pain and temperature fibers on both sides while initially sparing dorsal-column sensation. A cervical syrinx may give a shoulder-and-arm distribution, but symptoms depend on its location and extent.
Frequently asked questions
Where does the spinothalamic tract arise?
Dorsal horn projection neurons receiving primary afferent input; many pain and temperature afferents have small myelinated Aδ or unmyelinated C fibers and cell bodies in dorsal root ganglia.
What muscles does the spinothalamic tract supply?
The spinothalamic tract supplies the transmits sensory information upward rather than motor commands to muscles.
What is the sensory distribution of the spinothalamic tract?
Pain and temperature are prominent lateral components; coarse touch and pressure are associated with anterior components, with overlap between pathways.
What is the course of the spinothalamic tract?
Primary branches may run briefly in Lissauer's tract before a dorsal-horn relay; crossing projection fibers ascend in the anterolateral cord and brainstem to thalamic nuclei, including the VPL, with onward cortical projections.