Gray matter consists of cell bodies and processes of neurons and glial cells (with only a sparse amount of myelin present). Gray matter of the spinal cord is butterfly-shaped in transverse section. The gray matter is divided into a dorsal horn, a ventral horn, and intermediate substance (between the two horns).

Within gray matter, collections of neuron cell bodies (profiles of neuron cell columns) are called nuclei. Neurons of the dorsal horn form the nucleus proprius, which is capped by the substantia gelatinosa which has a marginal nucleus on its surface. The nucleus thoracicus and intermediolateral nucleus (lateral horn) are only found in thoracic and lumbar regions of spinal cord. Motor neurons that innervate skeletal muscle are found within the ventral horn.