The TMJ is the joint that connects the lower jaw to the base of the skull. The reason the name temporomandibular joint is used, is because it refers to the joint between the mandible (jaw) and the temporal bone (part of the skull). As you will know it is highly mobile and a well used joint for eating (the greatest strain on it), talking, yawning and even grinding of teeth during sleep!
The photograph below shows the bony landmarks for the temporomandibular joint. Remember these are only the bony areas and the cartilaginous disc and supporting capsule are missing, as are the muscle movers.
A normal TMJ
This video shows a normal joint working in schematic form. The video first shows the jaw-closing muscles and the ligaments which encase the joint. Then it shows the opening muscles at work and the position of the nerve and the disc. The disc moves during jaw opening. It shows the position of the disc when the jaws are closed. It sits between the mandible and temporal bone. When the mandible starts opening, the jaw hinges on this disc.
The following video shows normal movement and all the soft tissues associated with this joint:
TMD are a family of problems related to the jaw joint. It can develop for many reasons.