spinothalamisen

Spinothalamisen, also known as the spinothalamic tract, is a major sensory pathway that transmits pain, temperature, and crude touch from the body to the brain. It consists of two main components: the lateral spinothalamic tract, which carries pain and temperature, and the anterior spinothalamic tract, which conveys crude touch and pressure.

Anatomy and pathway: Primary sensory neurons reside in the dorsal root ganglia. Their central processes enter the spinal cord and typically synapse on second-order neurons in the dorsal horn (lamina I–III). The second-order neurons cross the midline at or near the level of entry via the anterior white commissure and then ascend on the contralateral side in the spinothalamic tract within the anterolateral column. These fibers terminate primarily in the ventral posterolateral nucleus (VPL) of the thalamus. Third-order neurons project from the VPL to the primary somatosensory cortex (postcentral gyrus); some projections also reach the insular cortex and cingulate areas, contributing to the affective aspects of pain.

Other pain pathways: The spinothalamic tract is part of a broader pain system that includes projections to brainstem and limbic structures, such as the spinoreticular and spinomesencephalic tracts, which contribute to arousal and reflexive responses to noxious stimuli.

Clinical relevance: Lesions of the spinothalamic tract produce contralateral loss or impairment of pain and temperature below the level of the lesion after crossing, with syringomyelia andBrown-Séquard syndrome illustrating related patterns. Assessment typically involves testing pinprick and thermal perception.