A study on the normal position of articular disk of the temporomandibular joint on MRI

ABSTRACT

To evaluate the normal range of articular disk postion, MRIs of 25 temporomandibular joints(TMJs) in 19 asymptomatic volunteers were analysed. On the closed mouth sagittal T1 weighted MRI the junction of the posterior band and bilaminar zone was within 10°anterior from the vertical line through the apex of condylar head in 19 (76%) lad within 20°in 23 (92%) TMJs. The intermediate zone of the articular disk was located between the posterior surface of articular eminence and the anterior surface of condylar head in 22 (88%) TMJs. We suggest that on the closed mouth sagittal MRI the junction of the posterior band and the bilaminar zone could be within 10°anterior from the vertical line through the apex of condylar head in asymptomatic Korean persons. If the junction is located more than 20°anterior from the vertical line or the intermediate zone is anterior to the anterior surface of condylar head it is suggested that the disk is anteriorly displaced. Further studies are needed to evaluate the clinical significance of mild anterior displacement of the articular disk(11°-20°) in asymptomatic persons.