Maxilla

The maxilla is the upper part of your jaw. It holds your top teeth in place and does not move. It also supports the muscles involved in chewing and facial expressions. It helps form the hard palate, which is the roof of the mouth.

The maxillary sinus is an air space inside it, just above the roots of the upper back teeth. Only a thin layer of bone separates them.

This closeness matters in dentistry. Sinus pressure can feel like an upper toothache. Removing an upper back tooth or placing an implant there may involve the sinus. A dentist uses x-rays to plan around it. See also the mandible.