Which cranial nerve provides sensory innervation to the skin of the head?

The trigeminal nerve, known as CN V, is the correct answer because it plays a pivotal role in providing sensory innervation to the skin of the head. This nerve has three major branches: the ophthalmic, maxillary, and mandibular nerves. Each branch is responsible for sensory functions in different regions of the face.

The ophthalmic branch supplies sensation to areas such as the forehead and upper eyelids, while the maxillary branch innervates the cheeks, upper lip, and part of the nasal cavity. The mandibular branch is responsible for sensation in the lower lip, chin, and part of the ear and temporomandibular joint. This extensive distribution makes the trigeminal nerve the primary sensory nerve of the face and scalp.

In contrast, the accessory nerve primarily provides motor innervation to the sternocleidomastoid and trapezius muscles and does not contribute to sensory functions. The facial nerve is mainly responsible for motor innervation of the facial muscles and provides sensory innervation to a small area around the ear and taste sensations from the anterior two-thirds of the tongue. The glossopharyngeal nerve is involved in taste and sensory functions from the posterior one-third of the tongue and the pharynx