Somatosensory pathways

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Two main pathways carry sensory information from our skin and joint afferents to our central nervous system:

• The posterior funiculus-medial lemniscus pathway transmits information about discriminative touch, vibration, pressure and proprioception
• The spinothalamic tract transmits information about non-discriminative touch, crude pressure, pain and temperature

Both pathways consist of three neurons: a receptor neuron that synapses in the medulla oblongata (posterior funiculus-medial lemniscus pathway) or spinal cord (spinothalamic tract), a neuron that synapses in the thalamus, and a neuron that reaches the somatosensory cortex.

Sensory information from both pathways reaches the contralateral cortex, but the two pathways decussate at different levels of the central nervous system. In both pathways, neurons cross over after the first synapse:

• Posterior funiculus-medial lemniscus pathway neurons cross over in the medulla oblongata
• Spinothalamic tract neurons cross over as they enter the spinal cord

This results in an important anatomical difference between the two pathways: sensory information about discriminative touch, vibration, pressure and proprioception travels up the spinal cord on the same side of the stimulus, whereas sensory information about non-discriminative touch, crude pressure, pain and temperature ascends the spinal cord on the opposite side of the body.

Watch the video below to understand more about how the posterior funiculus-medial lemniscus pathway and the spinothalamic tract transmit sensory information to the brain.

Explore concepts

Compare the posterior column-medial lemniscus pathway and the spinothalamic tract in the image gallery below.

Take a closer look at the structures of the posterior funiculus-medial lemniscus pathway in the gallery below.

Take a closer look at the structures of the spinothalamic tract in the gallery below.

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Summary