Anterior ethmoid Nerve.

http://en.wikipedia.org/wiki/Anatomy_of_the_human_nose

Conveys sensation in the anterior (front) half of the nasal cavity: (a) the internal areas of the ethmoid sinus and the frontal sinus; and (b) the external areas, from the nasal tip to the rhinion: the anterior tip of the terminal end of the nasal-bone suture.