The anocutaneous reflex involves afferent and efferent pathways from which spinal segments?

• A. L2-L4
• B. S2-S4
• C. C5-C8
• D. T12-L1

Answer: (B)

The anocutaneous (anal wink) reflex is a sacral spinal reflex driven by the pudendal nerve. Its afferent input from the perianal skin travels to the spinal cord at the sacral levels, and the efferent output to the external anal sphincter travels back out from those same levels. Both limbs of the reflex arc rely on the nerve roots S2 to S4. If these pathways are intact, the reflex can be elicited; if there’s a lesion or dysfunction in S2–S4 or the pudendal nerves, the reflex may be diminished or absent. The other spinal level options don’t contribute to the pudendal nerve or anal sphincter control (L2–L4 relates to the femoral nerve, C5–C8 to the upper limb, and T12–L1 to thoracolumbar).