Disc luxation
Disc luxation is a displacement of the joint disc. In the normal temporomandibular joint, the joint disc lies on top of the condyle head while the mouth is closed. If this cartilaginous disk moves forward, we speak of an anterior disk - displacement (anterior discus luxation). If the joint disk slides back again when the mouth opens, we speak of anterior discus luxation with reduction. The patient usually notices this by a cracking sound during the mouth, and usually a quieter cracking sound during the mouth-closing movement.
If the joint disc cannot jump back into its normal position (i.e., it remains in the position of being before the joint head the whole time), we speak of anterior discus luxation WITHOUT reduction. No cracking noise then occurs and the mouth opening is restricted.