**Core Concept**
The palatoglossus is a muscle in the tongue that plays a crucial role in elevating the tongue and helping to form the anterior pillar of the fauces. It is innervated by a branch of the cranial accessory nerve, which is a unique example of a cranial nerve that originates in the brainstem but exits the skull through the jugular foramen along with the vagus nerve.

**Why the Correct Answer is Right**
The cranial accessory nerve (CN XI) has a distinct relationship with the palatoglossus muscle. The nucleus ambiguus, which is the origin of the cranial accessory nerve, sends fibers to the palatoglossus muscle, allowing for coordinated movement of the tongue. This is in contrast to other muscles of the tongue, which are primarily innervated by branches of the trigeminal nerve (cranial nerve V). The cranial accessory nerve's involvement with the palatoglossus muscle is essential for proper tongue function and speech articulation.

**Why Each Wrong Option is Incorrect**
**Option A:** The glossopharyngeal nerve (cranial nerve IX) primarily provides sensory innervation to the tongue and is responsible for swallowing and taste. It does not innervate the palatoglossus muscle.
**Option B:** The hypoglossal nerve (cranial nerve XII) primarily innervates the extrinsic and intrinsic muscles of the tongue, except for the palatoglossus muscle. It is involved in tongue movement and protrusion, not elevation.
**Option D:** The mandibular nerve (a branch of the trigeminal nerve, cranial nerve V) primarily provides sensory innervation to the lower face, including the lower lip and jaw. It does not innervate the palatoglossus muscle.

**Clinical Pearl / High-Yield Fact**
The cranial accessory nerve is unique in that it has both a cranial and a spinal root, which merge to form the nerve that exits the skull. This distinction is essential to remember when identifying the innervation of muscles like the palatoglossus.

**✓ Correct Answer:** C. Cranial accessory nerve