Transmission 2 - spinal cord to brain

Sensory A and C fibres enter the spinal cord and synapse, or connect, with so called second order neurones in the dorsal horn of the spinal cord. These second order neurones cross over to the opposite side of the cord and pass up to the brain in groups of fibres called tracts.

There are a number of ascending tracts that carry pain information to the brain, including the spinothalamic tract which conveys the fibres to the thalamus deep within the cerebrum and the spinoreticular tract which conveys the fibres to a diffuse structure known as the reticular formation within the brain stem.

From here third order neurones convey the information to a number of areas of the brain.