Muscles of tongue are supplied by :
**Core Concept**
The muscles of the tongue are a group of intrinsic and extrinsic muscles that enable various movements of the tongue, including protrusion, retraction, elevation, and depression. These movements are crucial for functions such as speech, swallowing, and feeding.
**Why the Correct Answer is Right**
The correct answer involves the hypoglossal nerve, which is responsible for innervating the muscles of the tongue. The hypoglossal nerve (CN XII) is a motor nerve that arises from the brainstem and descends through the neck to reach the tongue. It supplies all the extrinsic and intrinsic muscles of the tongue, except for the palatoglossus muscle, which is supplied by the vagus nerve (CN X). The hypoglossal nerve enables the tongue to move in a coordinated manner, allowing for precise movements during functions such as speech and swallowing.
**Why Each Wrong Option is Incorrect**
* **Option A:** The glossopharyngeal nerve (CN IX) primarily supplies the stylopharyngeus muscle and provides sensory innervation to the posterior one-third of the tongue. It does not supply the muscles of the tongue.
* **Option B:** The vagus nerve (CN X) supplies the palatoglossus muscle and provides sensory innervation to the epiglottis and the larynx. It does not supply the majority of the muscles of the tongue.
* **Option D:** The facial nerve (CN VII) supplies the muscles of facial expression, including the muscles of the upper lip and the orbicularis oris muscle. It does not supply the muscles of the tongue.
**Clinical Pearl / High-Yield Fact**
The hypoglossal nerve is unique in that it is the only cranial nerve that has a motor nucleus located in the medulla oblongata, and it is the only cranial nerve that has a peripheral motor nucleus.
**Correct Answer:** C.