Embryogenesis of the human temporomandibular joint.

The structures of this articulation were found to originate from two different blastemata situated at some distance from each other and operating at different rates and opposing directions. A condylar blastema evolving dorsally contributes to the formation of the condylar cartilage, the disc, the aponeurosis of the external pterygoid muscle, and the capsular elements of the lower joint level, while a temporal blastema develops the articular structures of the upper level in a forward direction. At the end of the fourth fetal month all joint elements including a glenoid fossa and articular eminence are present in their primitive form.