What test can be used to assess the function of the facial nerve?

The function of the facial nerve, also known as cranial nerve VII, is primarily associated with the control of the muscles of facial expression. To effectively assess this nerve, it’s important to evaluate the patient's ability to perform movements that engage these muscles. Asking the patient to smile, frown, and raise their eyebrows is a direct way to test the integrity of the facial nerve because it activates the specific muscle groups innervated by this nerve.

Each facial expression requires coordinated muscle contractions that are controlled by the facial nerve. For instance, smiling engages the zygomaticus major and minor muscles, frowning activates muscles such as the corrugator supercilii, and raising the eyebrows involves the frontalis muscle. Observing these movements can help identify any weakness, asymmetry, or paralysis that may indicate facial nerve dysfunction.

In contrast to the correct choice, the other options evaluate different systems or cranial nerves. Sticking out the tongue assesses the function of the hypoglossal nerve (cranial nerve XII), reflex tests in the arms do not pertain to cranial nerve assessment, and the Romberg test evaluates the vestibular system and proprioception, relating more to the vestibulocochlear nerve (cranial nerve VIII)