Which cranial nerve is responsible for facial movement and expression, as assessed by puffing out cheeks?

The cranial nerve responsible for facial movement and expression is the facial nerve. This nerve controls the muscles of facial expression, allowing for actions such as puffing out the cheeks, smiling, and frowning. When conducting an assessment of facial movement, clinicians often ask patients to perform various expressions to evaluate the function of this nerve. Puffing out the cheeks specifically engages the buccinator muscle, which is innervated by the facial nerve, highlighting its role in controlling facial musculature.

Other cranial nerves listed here serve different functions: for example, the abducens nerve primarily controls lateral eye movement and is not involved in facial expression; the olfactory nerve is responsible for the sense of smell and does not have any role in motor functions; and the vagus nerve is involved in autonomic functions and voice. This context helps clarify the specific role of the facial nerve in relation to movements of the face.