Computer-aided graphical three-dimensional reconstructions of histological
serial sections of 12 human embryos and fetuses (25-250 mm Crown-rump lengt
h (CRL)) were used to trace the prenatal development of the elements of the
human temporomandibular joint. The primordia of the condylar and coronoid
processes could be identified as two bony peaks at the dorsal ends of the m
andible at the stage of 25 mm CRL. The primordium of the temporal bone alre
ady existed at the stage of 37 mm CRL. The bone was apparent with a convex
contour towards the condyle. The glenoid fossa was not yet visible. At 65 m
m CRL, the osseous glenoid fossa could be distinguished at the enlarged tem
poral bone formation. The glenoid fossa developed posteriorly and medially
from the condyle and extended in cranial and anterior direction. The glenoi
d fossa had various contours, changing from flat and slightly convex (65 mm
CRL) to concave (250 mm CRL) with an articular tubercle. The distance betw
een fossa and condyle increased proportionally. The lower joint cavity appe
ared at an earlier stage (65 mm CRL) than the upper joint cavity (70 mm CRL
). Both cavities started development as isolated compartments fusing later
on. The upper joint cavity followed the contour of the fossa, whereas the l
ower joint cavity followed the form of the condyle. The biconcave shape of
the articular disc as well as the attachment of the lateral pterygoid muscl
e could be observed very early (70 mm CRL).