Final answer:
The trigeminal nerve (cranial nerve V) is assessed by a nurse when a client is asked to clench their teeth. This nerve controls the muscles necessary for mastication.
Step-by-step explanation:
Which Cranial Nerve is Tested When Clenching Teeth?
The cranial nerve being tested when a nurse asks a client to clench their teeth and places their hand on the client's jaw is the trigeminal nerve (cranial nerve V). This nerve is responsible for motor functions including the muscles of mastication, allowing for the chewing actions.
The nurse is assessing the motor branch of the trigeminal nerve for any abnormalities or deficits in its function. In contrast, the facial nerve (cranial nerve VII) is assessed through facial expressions, such as raising eyebrows or smiling, while the vagus nerve (cranial nerve X) is checked by observing movements related to swallowing and the gag reflex. Each cranial nerve test targets specific nerve functions that are crucial in diagnosing any neurological issues.