Final answer:
The incorrect statement about the spinal cord is option b, as the gray matter, including the anterior and posterior horns, does not contain myelinated fibers; these are found in the white matter. The white matter has myelinated axons arranged in tracts for sensory and motor functions. All other options correctly describe the organization and function of spinal cord matter.
Step-by-step explanation:
The correct answer to the student’s question, which asks which statement is incorrect about the spinal cord, is option b: “The anterior gray horn and posterior gray horns contain myelinated fibers.” The gray matter of the spinal cord, which includes the anterior and posterior horns, is primarily composed of neuron cell bodies, interneurons, and is mainly involved in processing information. Gray matter does not contain myelinated fibers — those are actually located in the white matter of the spinal cord.
The white matter contains myelinated axons and is organized into columns. These columns contain tracts, which can be ascending or descending. Ascending tracts carry sensory information to the brain, while descending tracts carry motor commands away from the brain. Sensory inputs enter the spinal cord through the posterior (dorsal) horns, and motor commands leave the spinal cord through the anterior (ventral) horns.
Options a, c, d, and e are all correct. The white matter indeed contains tracts (a), the gray matter contains unmyelinated interneurons (c), motor tracts carry information away from the brain (d), and sensory tracts carry information to the brain (e).