Question

value: 10

a spinal root may be mixed (motor and sensory), but a spinal nerve must be only motor or sensory.

true
false

Explanation:

Analyze the anatomy of spinal roots

Using the Spinal Cord Anatomy knowledge point

Spinal roots emerge directly from the spinal cord:

• The dorsal (posterior) root contains only sensory (afferent) fibers.
• The ventral (anterior) root contains only motor (efferent) fibers.
• Therefore, spinal roots are purely sensory or purely motor, never mixed.

Analyze the anatomy of spinal nerves

Using the Spinal Cord Anatomy knowledge point

The dorsal and ventral roots merge laterally to form a spinal nerve:

• Because it is formed by the fusion of a sensory root and a motor root, every spinal nerve contains both sensory and motor fibers.
• Therefore, all spinal nerves are mixed nerves.

Evaluate the statement

Using the Spinal Cord Anatomy knowledge point

The statement claims: "A spinal root may be mixed (motor AND sensory), but a spinal nerve must be only motor OR sensory."

• This is the exact opposite of anatomical reality.
• Roots are purely sensory or motor, while nerves are mixed.
• Thus, the statement is false.

Answer:

• True
• (B) False (Correct answer)