Which cranial nerve controls facial expression?

The cranial nerve responsible for controlling facial expression is the Facial Nerve, also known as Cranial Nerve VII. This nerve innervates the muscles of facial expression, enabling a wide range of movements such as smiling, frowning, and other gestures that convey emotions and nonverbal communication. The Facial Nerve emerges from the brainstem and passes through the stylomastoid foramen, branching out to various muscle groups in the face.

This specific function of the Facial Nerve underscores its role in conveying emotional states and social cues through facial expressions, which are essential for interpersonal communication. Dysfunction of this nerve can result in conditions such as Bell's palsy, which can lead to paralysis or weakness on one side of the face.

In contrast, other cranial nerves listed have different responsibilities. The Trigeminal Nerve is primarily responsible for sensation in the face and certain motor functions such as chewing. The Glossopharyngeal Nerve is involved in taste and some aspects of swallowing. The Vagus Nerve innervates muscles of the throat and voice box, playing a key role in swallowing and vocalization but not in facial expression. Thus, the predominance of the Facial Nerve in this context makes it the correct answer.