Articular disc of temporomandibular joint

At a glance

English

Articular disc of temporomandibular joint

Latin (TA2)

Discus articulationis temporomandibularis

System

Cartilage

Region

Head

Side

Paired, left and right

About the articular disc of temporomandibular joint

The articular disc of the temporomandibular joint sits between the head (condyle) of the mandible below and the mandibular fossa and articular tubercle of the temporal bone above. It is made of dense fibrous tissue rather than true hyaline cartilage, and its central part has no blood vessels or nerves. Its fibres run in rings, a pattern clearest towards the edge. Because it spans the whole joint, the disc splits it into two separate synovial compartments, an upper and a lower one, each with its own synovial lining.

Its shape matches the bones on each side. The underside is hollowed to cap the rounded condyle. The upper side curves both ways when followed from front to back, being hollow under the fossa and bulging under the tubercle. In section it is a biconcave plate: thin in the middle, which is the part that bears load, and thicker at the rim, most of all at the back. These thicker front and back bands help keep it centred on the condyle.

All round its margin the disc is joined to the capsule. In front, upper fibres pass up to the articular eminence and lower ones to the front of the condyle, and part of the upper head of the lateral pterygoid inserts here. Behind, it continues into a loose, vascular, two-layered pad, the bilaminar zone or retrodiscal tissue: its upper elastic layer runs to the temporal bone behind the fossa and its lower layer to the back of the condylar neck. At the sides it is fixed firmly to the poles of the condyle, so disc and condyle move as a unit.

Hinging movements take place in the lower compartment, between condyle and disc, while gliding forwards onto the eminence when the mouth opens wide takes place in the upper compartment, between disc and temporal bone. The disc steadies the condyle and resists backward displacement of the mandible. When the disc slips forward off the condyle, the jaw may click on opening as it is recaptured, or lock if it is not; this internal derangement is a common part of temporomandibular disorders.

Attachments and function

Attaches from

Its upper surface faces the mandibular fossa and articular tubercle of the temporal bone, to which its posterior upper lamina attaches.

Attaches to

Its lower surface caps the head of the mandible; it is fixed to the medial and lateral poles of the condyle and to the joint capsule all round.

Function

Divides the joint into upper gliding and lower hinging compartments, matches the bone surfaces, spreads load and steadies the condyle, resisting backward displacement of the mandible.

Nerve supply

The capsule and retrodiscal tissue are supplied by the auriculotemporal and masseteric branches of the mandibular nerve; the centre of the disc has no nerves.

Blood supply

The periphery and retrodiscal tissue receive branches of the superficial temporal and maxillary arteries; the central part is avascular.