maxillary sinus

The maxillary sinuses are the largest of the four pairs of air-filled cavities in the bones surrounding the nose. These sinuses are present from the fourth month of intrauterine life and are pyramidal in shape. The roof of each maxillary sinus is formed by the floor of the eye socket, and its floor is made up of the palate and the bone that holds the upper teeth. The roots of the upper teeth can sometimes extend into the sinus cavity. These sinuses reach their full size around age 12.1

The paranasal sinuses, including the maxillary sinuses, are lined with a mucous membrane that produces mucus. This mucus is moved by cilia towards openings called ostia, which lead into the nasal cavity. The primary function of these sinuses is not fully understood, but theories suggest they may play a role in phonation, heat conservation, and lightening the skull. The most common issue affecting these sinuses is sinusitis, which is inflammation of their lining.12