Which nerve provides motor function to the muscles of mastication?

The mandibular nerve, which is the third branch of the trigeminal nerve (cranial nerve V), is responsible for providing motor function to the muscles of mastication. This includes the masseter, temporalis, and pterygoid muscles. These muscles are essential for the process of chewing, allowing for the movement of the jaw in various directions necessary for grinding and breaking down food.

While the trigeminal nerve encompasses several branches, only the mandibular division contains the motor fibers that innervate these muscles. The other branches, such as the maxillary and ophthalmic nerves, primarily carry sensory information and do not provide motor innervation to the muscles involved in mastication. The facial nerve is also primarily associated with muscles of facial expression and does not innervate the chewing muscles. Thus, the specificity of the mandibular nerve in performing this crucial function underlines why it is the correct answer.