A lesion that affects the CN VII's motor fibers to facial muscles but spares lacrimation would most directly affect which function?

• A. Closing the eye on the affected side
• B. Tasting the tongue
• C. Hearing
• D. Salivation

Answer: (A)

The key idea is that CN VII has distinct pathways: motor fibers to the muscles of facial expression, and separate parasympathetic fibers to lacrimal and salivary glands. If a lesion disrupts the motor fibers to facial muscles but leaves the lacrimal (parasympathetic) pathway intact, the function most directly dependent on facial muscle contraction will be impaired.

Closing the eye relies on the orbicularis oculi muscle, which is innervated by CN VII. When those motor fibers are affected, you can’t fully close the eye on the affected side, even though tear production from the lacrimal gland remains normal because lacrimation is spared.

Taste from the anterior tongue, hearing, and saliva production (to submandibular/sublingual glands) rely on other branches or pathways that aren’t the primary motor trunk to facial muscles, so they aren’t the function you’d expect to be most affected in this specific scenario.