Overview of Somatic Sensory Pathways

The somatic sensory pathways transmit impulses from sensory receptors to the cerebral cortex or the cerebellum.

These pathways are composed of bundles of nerve fibers called tracts arranged on opposite sides of the spinal cord. Each tract is composed of axons that originate and terminate at the same destination.

There are three major somatic sensory pathways.

The posterior column-medial lemniscus pathway transmits impulses for fine touch, vibration, and proprioception.

The spinothalamic pathway conducts impulses for pain, temperature, and crude touch.

Both of these pathways terminate in the primary somatosensory cortex and contribute to conscious perception.

The spinocerebellar pathway carries proprioceptive impulses that are not consciously perceived. This is because this pathway does not reach the cerebral cortex but instead terminates in the cerebellum.

The somatosensory pathways start with first-order neurons that transmit impulses from receptors to the spinal cord or brainstem.

Then, second-order neurons carry the impulse to the cerebellum or thalamus.

Finally, third-order neurons conduct impulses from the thalamus to the primary somatosensory area of the cerebral cortex.