Articular capsule of temporomandibular joint

At a glance

English

Articular capsule of temporomandibular joint

Latin (TA2)

Capsula articularis articuli temporomandibularis

System

Joint

Region

Head

Side

Paired, left and right

About the articular capsule of temporomandibular joint

The articular capsule of the temporomandibular joint is a slack sleeve of fibrous tissue enclosing the joint between the head of the mandible and the temporal bone. Above it is fixed around the rim of the mandibular fossa and to the front of the articular tubercle; below it attaches to the mandibular neck, just under the condyle. The two jaw joints work together as a single unit, since the mandible is one bone, and neither can move without the other.

Inside the capsule lies the articular disc, a biconcave plate of dense fibrous tissue that is fused to the capsule all round its edge. The disc splits the joint into two synovial compartments, one above it and one below. Its front edge is joined by fibres of the superior head of lateral pterygoid, and its back edge continues into the bilaminar retrodiscal tissue, which is soft, vascular and rich in nerves. The synovial membrane lines the inside of the capsule but not the load-bearing surfaces of the disc or the fibrocartilage on the condyle.

The lateral side of the capsule is thickened as the temporomandibular ligament. It runs from the zygomatic process and articular tubercle down and back to the neck of the mandible, and its outer oblique and inner horizontal parts stop the condyle from being driven back and down. Two accessory bands, the sphenomandibular and stylomandibular ligaments, lie apart from the capsule.

The loose capsule allows two kinds of movement. In the lower compartment the condyle rotates under the disc for the first part of mouth opening; in the upper compartment disc and condyle slide forward together on to the articular tubercle for wider opening and protrusion. Excess laxity lets the condyle slip in front of the tubercle in a dislocated jaw. The commonest disorder is disc displacement, often heard as a click on opening, and the capsule can also be inflamed in capsulitis and synovitis.

Attachments and function

Formed by

Attached above to the temporal bone around the mandibular fossa and along the front of the articular tubercle.

Joins

Fixed below on the mandibular neck, around the condyle; its inner surface is fused to the edge of the articular disc.

Movements

Encloses the jaw joint and its two synovial compartments, allowing rotation and forward gliding of the condyle while its lateral thickening resists backward displacement.

Nerve supply

Sensory twigs from the mandibular nerve (V3), through its auriculotemporal and masseteric branches.

Blood supply

Chiefly the superficial temporal artery from the external carotid, helped by the maxillary artery and its deep auricular and anterior tympanic branches.