TMJ Dislocation

Summary:

 
Normal anatomy:

-During the closed mouth the disc is seen at 11 oclock to the mandibular condyle.

-During the open mouth the disc remain between the mandibular condyle and the articular eminence as the condyle translate anteriorly.
-MRI Signals---T1--->Intermediate.
                          T2--->Hyper intense

Abnormal Findings: 

-Abnormal disc morphology and position are the earliest and most sensitive signs of internal dearrangement.

-Disc signals---Loss of hyper intense signal.

-Disc morphology---Become biconvex, thickened, folded or may perforate.
-Late in the disease, the disc may be fixed anteriorly during open and closed mouth.
+fluid accumulation
+cortical erosion
+condylar head flattening
+anterior osteophytosis.
+sub chondral marrow edema
+ finally sclerosis
Remember that the position of the disc should be assessed on sagittal closed mouth image---normally it should be between condyle and articular surface.
Remember that disc displaces normally anteriorly during open mouth.