TMJ stands for temporomandibular joint dysfunction. This disorder connects your jawbone to your skull causing discomfort and pain when the muscles have movement. There are different causes to TMJ/TMD, in some cases grinding of the teeth can be a cause, but for most part it can come from other problems such as genetics, arthritis or jaw injury.
If you are experiencing any symptoms related to TMJ/TMD, you should see a dentist to treat it.