Temporomandibular joint dysfunction, commonly known as TMJ dysfunction or TMD, is a condition that affects the joint connecting the jawbone to the skull. The temporomandibular joint (TMJ) allows you to move your jaw for activities like chewing, speaking, and yawning. TMJ dysfunction occurs when there is an issue with the jaw joint and surrounding muscles, resulting in pain, discomfort, and difficulty in jaw movement. It can be caused by various factors, such as jaw misalignment, teeth grinding, stress, arthritis, or injury to the joint.