Final answer:
In a sensory assessment of the facial nerve, smiling and frowning should be assessed, as these movements test the motor functions responsible for facial expression. The strength test may be repeated to confirm muscle strength and detect any nerve-related deficits. Blinking, associated with the corneal reflex, also involves the facial nerve.
Step-by-step explanation:
In a sensory assessment of the facial nerve, the facial movements that should be assessed are Option 2: Smiling and frowning. These movements test the motor functions of the facial nerve, which are responsible for controlling the muscles of facial expression. Testing may also involve having the patient raise their eyebrows or squeeze their eyes shut against resistance. The strength test in the provided video, which includes having the patient attempt to close the eyes while the examiner tries to open them, is perform a second time to confirm muscle strength and look for any asymmetry or weakness that might indicate a nerve deficit.
The trigeminal nerve, on the other hand, is tested with the stretch reflexes associated with the muscles of chewing. The gag reflex, which is tested during the cranial nerve exam, involves the motor control of the vagus nerve.
The sensory component of the corneal reflex, or blink reflex, is mediated by the trigeminal nerve, while the motor response is through the facial nerve. This reflex is assessed by a tactile stimulus or bright light, initiating blinking.