**Core Concept**
The superior oblique muscle is one of the six extraocular muscles responsible for controlling eye movements. The nerve supply to this muscle is crucial for its function and is associated with the trochlear nerve, which is the fourth cranial nerve (CN IV).

**Why the Correct Answer is Right**
The trochlear nerve (CN IV) is unique as it is the only cranial nerve that emerges from the dorsal aspect of the brainstem, specifically from the trochlear nucleus. This nerve then descends through the lateral wall of the cavernous sinus and exits the skull through the superior orbital fissure. The trochlear nerve then supplies the superior oblique muscle, which is responsible for the rotation of the eyeball around its longitudinal axis, particularly depressing the eyeball and rotating it inward.

**Why Each Wrong Option is Incorrect**
**Option A:** The oculomotor nerve (CN III) supplies the majority of the extraocular muscles, including the medial rectus, superior rectus, inferior rectus, and inferior oblique muscles. However, it does not supply the superior oblique muscle.
**Option B:** The abducens nerve (CN VI) supplies the lateral rectus muscle, which is responsible for outward eye movement, but not the superior oblique muscle.
**Option C:** The facial nerve (CN VII) is primarily responsible for controlling facial expressions and does not supply the extraocular muscles.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the trochlear nerve (CN IV) is the only cranial nerve that decussates (crosses over) before exiting the brainstem, making it unique among the cranial nerves.

**Correct Answer: C. Abducens nerve.**