Lateral spinothalamic tract

The lateral spinothalamic tract, also known as the lateral spinothalamic fasciculus, is an ascending pathway located anterolaterally within the peripheral white matter of the spinal cord. It is primarily responsible for transmitting pain and temperature as well as coarse touch.

The anterior spinothalamic tract (discussed separately), in contrast, primarily transmits coarse touch and pressure.

Gross anatomy

Peripheral connections

First-order neurons, whose cell bodies are in the dorsal root ganglion and whose axons extend from peripheral receptors, enter the cord via dorsal nerve roots.

Central course 

The aforementioned first-order neurons synapse with second-order neurons whose bodies are located in the ipsilateral dorsal horn of the cord. In contrast to the anterior spinothalamic tract, whose fibers ascend for some levels before decussating, these second-order neurons' axons cross almost immediately via the anterior spinal commissure and form the lateral spinothalamic tract .

The lateral spinothalamic tract then ascends in the lateral funiculus, just medial to the ventral spinocerebellar tract. Fibers of this tract are somatotopically organized for their entire course.

Upon reaching the brainstem, the lateral and anterior spinothalamic tracts combine to form the spinal lemniscus, which runs lateral to the medial lemniscus. The spinal lemniscus terminates in the ventral posterior nucleus of the thalamus. Here, it synapses with third-order neurons, which project to the primary somatosensory area on the ipsilateral side of the cerebral cortex.

Related pathology