**Core Concept**
The palatoglossus muscle is one of the muscles of the soft palate, playing a crucial role in elevating the tongue and aiding in swallowing. The muscle is innervated by a cranial nerve that originates from the brainstem.

**Why the Correct Answer is Right**
The palatoglossus muscle is primarily innervated by the cranial nerve X (vagus nerve), specifically through its pharyngeal branch. This nerve branch originates from the vagus nerve and provides motor innervation to the palatoglossus muscle. The pharyngeal branch of the vagus nerve also provides sensory innervation to the pharynx.

**Why Each Wrong Option is Incorrect**
**Option A:** The hypoglossal nerve (cranial nerve XII) primarily innervates the extrinsic and intrinsic muscles of the tongue, excluding the palatoglossus muscle.
**Option B:** The glossopharyngeal nerve (cranial nerve IX) provides sensory innervation to the pharynx and motor innervation to the stylopharyngeus muscle, but not the palatoglossus muscle.
**Option C:** The lingual nerve, a branch of the mandibular division of the trigeminal nerve (cranial nerve V), provides sensory innervation to the tongue, but not the motor innervation to the palatoglossus muscle.

**Clinical Pearl / High-Yield Fact**
The palatoglossus muscle helps to elevate the tongue and aid in swallowing by contracting and pulling the tongue upwards towards the palate. This action is essential for preventing food and liquid from entering the nasal cavity during swallowing.

**Correct Answer: C. The glossopharyngeal nerve (cranial nerve IX) primarily innervates the palatoglossus muscle, via its pharyngeal branch, providing motor innervation.