Which cranial nerve is primarily responsible for facial sensation?

The Trigeminal nerve, known as cranial nerve V, is primarily responsible for facial sensation. This nerve is crucial because it has three major branches: the ophthalmic, maxillary, and mandibular nerves. Each branch innervates different areas of the face, allowing it to convey sensory information such as touch, pain, and temperature from various facial regions to the brain.

In contrast, the Oculomotor nerve (CN III) is involved mainly in eye movement and pupil constriction, not facial sensation. The Facial nerve (CN VII) is primarily responsible for facial expression and carries some sensory taste information from the anterior two-thirds of the tongue rather than general facial sensation. Finally, the Optic nerve (CN II) is dedicated to vision and does not play a role in facial sensation. Thus, the Trigeminal nerve is the correct answer as it directly influences our ability to perceive sensations across the face.