Composition of the cord

The gray matter is composed of nerve cell bodies and unmyelinated intemeuron fibers. The location of the gray matter in the spinal cord is opposite to that of the brain. In the brain, the gray matter of the cerebrum and the cerebellum is found externally forming a cortex, or covering, over the internally located white matter. In the spinal cord, the gray matter is found internally and is surrounded by the white matter. 

The white matter is composed of myelinated axons of neurons. These axons are grouped together according to function to form tracts. Neurons transmitting impulses toward the brain in the ascending tracts carry sensory information. Those transmitting impulses away from the brain in the descending tracts carry motor information. 

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