When a client is asked to protrude their tongue and it is observed to be midline, which cranial nerve is being assessed?

The observation of the tongue being midline when a client is asked to protrude it is an assessment of the hypoglossal nerve, also known as cranial nerve XII. This nerve controls the movements of the tongue, which are essential for speech and swallowing. When the tongue protrudes symmetrically and remains midline, it indicates that the hypoglossal nerve is functioning properly and that there are no neurological issues affecting tongue movement.

Other cranial nerves mentioned play different roles. The glossopharyngeal nerve (cranial nerve IX) is primarily involved in taste and swallowing. The vagus nerve (cranial nerve X) is responsible for various autonomic functions including heart rate, gastrointestinal peristalsis, and certain muscle movements in the vocal cords. The facial nerve (cranial nerve VII) controls the muscles of facial expression and has some responsibility in taste sensations. Therefore, these nerves do not directly assess tongue protrusion and positioning in the way cranial nerve XII does.