The frontal nerve is a branch of the ophthalmic nerve, which is part of the trigeminal nerve (CN V). It primarily provides sensory innervation to the forehead, scalp, and upper eyelid. This nerve plays a crucial role in transmitting sensory information, such as touch and pain, from these areas to the brain. In addition to its sensory functions, the frontal nerve divides into two main branches: the supraorbital nerve and the supratrochlear nerve. The supraorbital nerve supplies sensation to the forehead and scalp, while the supratrochlear nerve innervates the skin of the medial forehead. Together, they ensure proper sensory feedback from the frontal region of the head.