Tissue Identification of the TMJ Disk and Disk Attachments and Related Vascularization

In this study, the authors described the collagenous tissue of the disk and disk attachments of the temporomandibular joint (TMJ) in Macaca fascicularis monkeys and the area's vascularization. The authors subjected five monkey heads to perfusion fixation and removed the right TMJ en bloc. After decalcification and sectioning, the sections were routinely stained for tissue identification and examined in polarized light. Frozen sections from the six TMJs from three unfixed monkey heads were used for enzyme histochemistry.

The dense collagenous tissue of the disk contained no chondrocytes. In polarized light the dense central biconcave part demonstrated birefringence throughout the entire thickness of the disk. This indicates parallel orientation of the fibers, which run in an anteroposterior direction. Within the anterior and posterior bands, the fibers spread out towards the attachments.

Enzyme histochemistry showed vessels within the loose connective tissue of the attachments, but no vessels were seen to penetrate into the dense connective tissue forming the disk. The vascularized fascia of the upper part of the superior lateral pterygoid muscle continued into the disk. The muscle fibers did not run into the disk but appeared in the anterior part of the capsule and inserted into the condylar neck.