What component of the spinal cord is primarily composed of neuron cell bodies?

• A. White matter
• B. Dorsal root
• C. Gray matter
• D. Funiculi

Answer: (C)

Gray matter is the region of the spinal cord that contains neuron cell bodies, along with their dendrites and synapses. In a cross-section it sits in the inner, butterfly-shaped core. The ventral horns hold motor neuron cell bodies that send their axons out to muscles, while the dorsal horns process incoming sensory information. Surrounding this is white matter, which is packed with myelinated axons forming the ascending and descending tracts that carry signals up and down the spinal cord. The dorsal root and dorsal root ganglion involve sensory fibers, but the cell bodies there are outside the spinal cord itself, and the funiculi are white-matter tracts. So, the region primarily composed of neuron cell bodies is gray matter.