Final answer:
The hypoglossal nerve originates from the medulla oblongata, exits the skull through the hypoglossal canal, and controls the muscles of the tongue. The extrinsic muscles of the tongue allow movement in various directions. Impairment of the hypoglossal nerve can affect speech and swallowing.
Step-by-step explanation:
The hypoglossal nerve is a motor nerve that controls the muscles of the tongue, except for the palatoglossus muscle which is controlled by the vagus nerve. It originates from the medulla oblongata in the brainstem and exits the skull through the hypoglossal canal. The hypoglossal nerve plays a crucial role in tongue movement and is responsible for actions such as protrusion, retraction, and flattening of the tongue.
The extrinsic muscles of the tongue, which are connected to other structures, include the genioglossus, styloglossus, palatoglossus, and hyoglossus muscles. These muscles allow the tongue to move in different directions, such as downward, forward, upward, and backward. Function of the hypoglossal nerve can be tested by assessing tongue movement, and impairment of this nerve can affect speech, swallowing, and other functions.