The frontal sinuses are air-filled cavities located in the forehead region, just above the eyes. They are part of the paranasal sinuses, which also include the maxillary, ethmoid, and sphenoid sinuses. These sinuses help to lighten the weight of the skull, produce mucus, and contribute to voice resonance. Frontal sinuses vary in size and shape among individuals and typically develop during adolescence. They are lined with a mucous membrane that helps trap and clear out pathogens and debris. Infections or blockages in the frontal sinuses can lead to conditions like sinusitis, causing pain and pressure in the forehead area.