fig 3.

10-year-old girl.

A, A transverse section of sonography of the right TMJ obtained while the patient was in the closed-mouth position. Note a hyperechoic line (arrowhead) running lateral and parallel to the lateral surface (arrow) of the mandibular condyle, indicating the articular capsule. The distance between the articular capsule and the lateral surface of the mandibular condyle is 4 mm.

B, A sagittal proton density–weighted image of the right TMJ obtained while the patient was in the closed-mouth position. Note the posterior band of the articular disk located anterior to the mandibular condyle (anterior disk displacement). The evaluation of the disk displacement on A is a true-positive result.

C, A transverse section of sonography of the left TMJ obtained while the patient was in the closed-mouth position. The distance between the articular capsule (arrowhead) and the lateral surface (arrow) of the mandibular condyle is 3 mm.

D, A sagittal proton density–weighted image of the left TMJ obtained while the patient was in the closed-mouth position. Note the posterior band of the articular disk located superior to the mandibular condyle (normal superior position). The evaluation of the disk displacement on C is a true-negative result.