Somatosensory System Anatomy

Somatosensory System Anatomy

Write a short note on the lateral spinothalamic tract.

Answer. 

Somatosensory System is a part of the spinothalamo-cortical pathway. It carries pain and temperature sensations from the opposite side of the body to the brain.

• First-order neurons are found in the dorsal root ganglia. Their central processes (axons) enter the spinal cord through the lateral division of the dorsal root of the spinal nerve and relay in the posterior horn of the spinal cord.
• Second-order neurons are found in the posterior horn. Their axons cross to the opposite side in the anterior white commissure and ascend in the contralateral white column (lateral spinothalamic tract). These axons terminate in the thalamus (ventral posterolateral [VPL] nucleus).
• Third-order neurons are found in the VPL nucleus of the thalamus. They project through the posterior limb of the internal capsule to the primary somatosensory cortex (Brodmann areas 3, 1, and 2).

Somatosensory System Applied anatomy

The damage of the lateral spinothalamic tract results in contralateral loss of pain, touch (simple/crude), and temperature sensations.