"T M J" are the first letters of the three anatomic parts of the head.

T= Temporal bone (skull), M= Mandible (lower jaw), J= Joint (connects two bones together) and called temporo-mandibular-joint.

The TMJ is one of the most complex joints in the body. It is composed of a large group of delicate small muscles, nerves, blood vessels, ligaments, tendons, cartilage, disc, synovial fluid, retrodiscal tissue: each part works in harmony with other parts much like a symphony orchestra.

All body joints (neck, shoulder, back, hip, knee, wrist, elbow, ankle, finger) have hinge movement or circular movement or a combination of both. However, TMJ has not only hinge and circular movement, it also has a gliding movement, in and out of the socket (glenoid fossa): we call it "Ginglymoarthroidal joint".

The function of the TMJ is to hold the lower jaw to the head within a certain boundary, and guide the jaw movements for chewing, talking, singing, yawning, breathing, swallowing, keeping the airway open while sleeping, and maintaining body posture and balance, etc.

—TMJ - Temporomandibular Joint, —TMD- Temporomandibular Joint Disorder, —Temporomandibular Joint Dysfunction, —Temporomandibular Joint Syndrome