The frontal bone forms the bony part of the forehead and is divided at birth (the two parts fuse in early life). The paired frontal sinuses (a paranasal sinus) behind the brow drain into the middle meatus of the nose via the frontonasal duct. Landmarks include the superciliary arch (supraorbital/brow ridge) and supraorbital foramen (notch, if incomplete) through which passes the supraorbital nerve (a branch of CN II) that provides forehead (and scalp) sensory supply.