The sphenoidal sinus is a pair of air-filled spaces located within the sphenoid bone, which is situated behind the nose and between the eyes. These sinuses are part of the paranasal sinus system and help to lighten the weight of the skull, improve voice resonance, and provide insulation for surrounding structures. The sphenoidal sinuses drain into the nasal cavity through small openings. They can be affected by conditions such as sinusitis, which is the inflammation of the sinuses, leading to symptoms like facial pain, congestion, and headaches. Proper drainage is essential for maintaining sinus health.