The maxillary sinus has numerous functions, most of which it shares with the other paranasal sinuses. As an air-filled cavity, the sinus helps lower the weight of the skull, making neck movements easier. It also humidifies and warms inspired air while contributing to the production of nasal mucus. Additionally, the sinus acts as a cushion to dampen and absorb some impact forces. It is lined with ciliated pseudostratified columnar epithelium. The cilia, which increase in number as they approach the ostium, play a role in mucociliary clearance. This clearance acts as a physical barrier, transporting debris and mucus toward the sinus ostium in a spiral fashion. Clearance through the ostium is more difficult in the maxillary sinus compared to the other paranasal sinuses, primarily because the maxillary sinus ostium is located above the sinus in the highest portion of the medial wall.