The frontal sinus (latin: sinus frontalis) is a paired air-filled, triangular-shaped cavity located the most superior of all paranasal sinuses, situated within the frontal bone.
The frontal sinuses are situated behind the superciliary arches, between the outer and inner tables of the frontal bone and they may extend posteriorly till the lesser wings of the sphenoid bone.
Each frontal sinus opens into the middle nasal meatus via the frontonasal duct that opens in the nasal cavity at the hiatus semilunaris.
The blood vessels supplying the frontal sinus include the supraorbital and anterior ethmoidal arteries and blood is collected from this region by their accompanying veins.
The sensory innervation of the mucosa lining the frontal sinus is provided by branches of the supraorbital nerve, and also the orbital branches arising from the pterygopalatine ganglion.