The frontal nerve is a branch of the ophthalmic nerve, which is part of the trigeminal nerve (cranial nerve V). It primarily provides sensory innervation to the forehead, scalp, and upper eyelid. The frontal nerve divides into two main branches: the supraorbital nerve and the supratrochlear nerve, which help transmit sensory information from these areas to the brain. In addition to its sensory functions, the frontal nerve plays a role in the autonomic nervous system by influencing blood flow and sweat production in the forehead region. Understanding the frontal nerve is important in fields like neurology and ophthalmology, especially during surgical procedures involving the face and head.