The hypoglossal nerve (CN XII) controls the tongue. This twelfth cranial nerve is primarily a motor nerve, meaning it sends signals to muscles to cause movement. It doesn't control taste, which is handled by other cranial nerves.
Understanding the Hypoglossal Nerve's Role
The hypoglossal nerve innervates the muscles of the tongue, enabling a wide range of movements crucial for:
- Speech: Articulating sounds requires precise tongue control.
- Chewing: The tongue manipulates food during mastication.
- Swallowing: Tongue movement is essential for pushing food towards the pharynx.
The hypoglossal nerve controls several key tongue muscles, including:
- Genioglossus: Protrudes the tongue.
- Hyoglossus: Depresses and retracts the tongue.
- Styloglossus: Elevates and retracts the tongue.
- Intrinsic muscles: These muscles control the tongue's shape and fine movements.
Damage to the Hypoglossal Nerve
Damage to the hypoglossal nerve can result in difficulties with speech, chewing, and swallowing. Symptoms can vary depending on the extent and location of the damage. These symptoms could include weakness, atrophy, or fasciculations (twitching) of the tongue muscles.
Sources confirm the hypoglossal nerve's primary role:
- Cleveland Clinic: "Your hypoglossal nerve enables tongue movement. It controls your hyoglossus, intrinsic, genioglossus and styloglossus muscles."
- StatPearls: "The hypoglossal nerve is mainly a somatic efferent (motor) nerve to innervate the tongue musculature."
- TeachMeAnatomy: "Its name is derived from ancient Greek, 'hypo' meaning under, and 'glossal' meaning tongue. The nerve has a purely somatic motor function,"
