<p>Your jaw is a set of bones that holds your teeth. It includes:</p> <ul> <li>The <strong>maxilla,</strong> which is the upper part of your jaw. It holds your top teeth in place and doesn't move. It also supports the muscles involved in chewing and facial expressions.</li> <li>The <strong>mandible,</strong> which is the lower part of your jaw. You move it when you talk or chew. It also holds your lower teeth in place.</li> <li>The <strong>temporomandibular joints</strong> (TMJs), which are two joints (one on each side) that connect your mandible to your skull.</li> </ul> <p>Jaw problems can include:</p> <ul> <li><a href="https://medlineplus.gov/fractures.html">Fractures</a> (broken bones).</li> <li><a href="https://medlineplus.gov/dislocations.html">Dislocations</a>, which are joint injuries that force the ends of your bones out of position.</li> <li><a href="https://medlineplus.gov/temporomandibulardisorders.html">Temporomandibular disorders</a> (TMDs), which are conditions that affect your TMJs.</li> <li><a href="https://medlineplus.gov/osteonecrosis.html">Osteonecrosis</a>, which happens when the blood flow to part of your bone is disrupted. It can cause the bone to break down.</li> <li>Jaw tumors, which can be benign (not cancer) or cancer.</li> <li>Jaw defects, which are <a href="https://medlineplus.gov/birthdefects.html">birth defects</a> in which your jaw could be missing or deformed.</li> </ul> <p><a href="https://medlineplus.gov/diagnosticimaging.html">Diagnostic imaging tests</a> are often used to diagnose jaw injuries and disorders. Your treatment will depend on which jaw problem you have.</p>