Which cranial nerve is assessed when asking the client to shrug their shoulders and to turn their head against passive resistance?

• A. Cranial nerve II
• B. Cranial nerve XI
• C. Cranial nerve IX
• D. Cranial nerve XII

Answer: (B)

Testing the ability to shrug the shoulders and to turn the head against resistance directly targets cranial nerve XI, the accessory nerve. This nerve innervates two muscles essential for these actions: the trapezius, which elevates the shoulders for a shrug, and the sternocleidomastoid, which turns the head and helps flex the neck. When you ask someone to shrug against resistance, you’re evaluating the trapezius and thus the function of CN XI. When you ask them to turn their head against resistance, you’re assessing the sternocleidomastoid, again reflecting CN XI integrity. If these movements are strong and coordinated, CN XI is functioning properly. The other nerves listed don’t control these muscles—vision is governed by the optic nerve, swallowing and some tongue movements by the glossopharyngeal and hypoglossal nerves—so they don’t explain the observed shoulder shrug or head-turn ability.