Certified Rehabilitation Registered Nurse (CRRN) Practice Exam

What indicates damage to the VII cranial nerve in a patient?

1. Cannot wink

2. Cannot clench teeth

3. Demonstrates ptosis

4. Can chew without problems but cannot smile

The correct answer is: Demonstrates ptosis

Damage to the VII cranial nerve, also known as the facial nerve, typically manifests through a variety of motor deficits, particularly in the muscles of facial expression. A key indicator of this damage is the inability to elevate the upper eyelid, leading to ptosis, which is a drooping or falling of the upper eyelid. This often occurs because the facial nerve controls not only facial expressions but also some functions of the eyelids. The facial nerve's role in lifting the eyelid is significant; therefore, observing ptosis in a patient suggests that the nerve's function has been compromised. In contrast, the other options—such as an inability to wink, clench teeth, or smile—all relate to either different cranial nerves (e.g., clenching teeth is mainly managed by the trigeminal nerve) or represent functions that might still be intact depending on the extent and specific nature of the VII cranial nerve damage. Thus, observing ptosis serves as a clear and definitive sign of involvement of the facial nerve, making it the most accurate choice in identifying cranial nerve VII impairment.