Final answer:
The hypoglossal nerve is the main motor nerve for the tongue muscles, aiding in essential functions such as speaking and swallowing, with the exception of the palatoglossus muscle, which is innervated by the vagus nerve. A clinical assessment of its function is part of a neurological examination.
Step-by-step explanation:
The hypoglossal nerve, also known as the twelfth cranial nerve, is responsible for the motor innervation of the muscles of the tongue, which play a crucial role in food manipulation, swallowing, and speech. The genioglossus muscle, one of the major muscles controlled by the hypoglossal nerve, facilitates the protrusion of the tongue.
An impairment of the hypoglossal nerve function can be identified during a physical exam where the patient is asked to "stick out your tongue," assessing the nerve's ability to control tongue movement properly. Should there be damage to one side of the nerve, the tongue will deviate towards the affected side, signifying a potential nerve or adjacent structure issue. The palatoglossus muscle, however, is an exception and is innervated by the vagus nerve.