Distribution of primary afferent fibres from the forelimb of the rat to the upper cervical spinal cord in relation to the location of spinothalamic neuron populations.

Abstract

Half the monosynaptic spinothalamic neurons in the rat spinal cord lie in the first 4 cervical segments, predominantly in the internal basilar column and ventral horn. The present study shows that both these regions receive primary afferents from the forelimb. The superficial dorsal horn receives few, and the region of the lateral cervical nucleus no primary afferents from the brachial plexus. We suggest that internal basilar column cells may represent localised relays concerned with the limbs, and that the gracile and cuneate nuclei are not unique, but are paralleled by other neuron populations in the upper cord.