Which cranial nerve is tested by having the patient raise eyebrows, frown, and smile?

Which cranial nerve is tested by having the patient raise eyebrows, frown, and smile?

• A. Cranial Nerve IV (CN IV)
• B. Cranial Nerve VII (CN VII)
• C. Cranial Nerve V (CN V)
• D. Cranial Nerve VI (CN VI)

Answer: (B)

Raising eyebrows, frowning, and smiling test the muscles of facial expression, which are controlled by the facial nerve. The facial nerve innervates key facial muscles such as the frontalis (raises the eyebrows), the corrugators (frowning), and the zygomaticus major (smiling). By asking the patient to perform these movements, you’re specifically assessing the motor function of CN VII. If weakness or asymmetry appears during these tasks, it points to a problem with the facial nerve on that side. The other nerves listed don’t primarily control these facial movements: the nerves that move the eyes (trochlear and abducens) regulate extraocular muscles, and the trigeminal nerve handles facial sensation and muscles of mastication. None of these explain the ability to raise the eyebrows, frown, and smile in a coordinated facial-expression test.

Raising eyebrows, frowning, and smiling test the muscles of facial expression, which are controlled by the facial nerve. The facial nerve innervates key facial muscles such as the frontalis (raises the eyebrows), the corrugators (frowning), and the zygomaticus major (smiling). By asking the patient to perform these movements, you’re specifically assessing the motor function of CN VII. If weakness or asymmetry appears during these tasks, it points to a problem with the facial nerve on that side.

The other nerves listed don’t primarily control these facial movements: the nerves that move the eyes (trochlear and abducens) regulate extraocular muscles, and the trigeminal nerve handles facial sensation and muscles of mastication. None of these explain the ability to raise the eyebrows, frown, and smile in a coordinated facial-expression test.