Temporomandibular Joint Anatomy

The temporomandibular joints (TMJs) are two of the most frequently used joints in the body, but they probably receive the least attention. They are located just anterior to the external auditory meatus (the ear).

Both joints, one on each side of the jaw, must be considered together in any examination. Along with the teeth, these joints are considered to be a “trijoint complex.”

Temporomandibular Joint Anatomy

The Temporomandibular Joint is a synovial, condylar, modified ovoid, and hinge-type joint with fibrocartilaginous surfaces rather than hyaline cartilage and an articular disc; this disc completely divides each joint into two cavities.

The capsule of the TMJs is thin and loose. In the resting position, the mouth is slightly open, the lips are together, and the teeth are not in contact but slightly apart. In the close packed position, the teeth are tightly clenched, and the heads of the condyles are in the posterior aspect of the joint. Centric occlusion is the relation of the jaw and teeth when there is maximum contact of the teeth, and it is the position assumed by the jaw in swallowing. The position in which the teeth are fully interdigitated is called the median occlusal position.

The temporomandibular, or lateral, ligament restrains movement of the lower jaw and prevents compression of the tissues behind the condyle. In reality, this collateral ligament is a thickening in the joint capsule. The sphenomandibular and stylomandibular ligaments act as “guiding” restraints to keep the condyle, disc, and temporal bone firmly opposed. The stylomandibular ligament is a specialized band of deep cerebral fascia with thickening of the parotid fascia.

Nerve Supply of TMJ

The TMJs are innervated by branches of the auriculotemporal nerve and masseteric branches of the mandibular nerve. The disc is innervated along its periphery but is aneural and avascular in its intermediate (force-bearing) zone

Blood Supply of TMJ

The arterial supply to the TMJ is provided by the branches of the external carotid, principally the superficial temporal branch. Other contributing branches include the deep auricular, ascending pharyngeal and maxillary arteries.

Temporomandibular Joint Movements

Gliding, translation, or sliding movement occurs in the upper cavity of the temporomandibular joint, whereas rotation or hinge movement occurs in the lower cavity. Rotation occurs from the beginning to the midrange of movement. The upper head of the lateral pterygoid muscle draws the disc, or meniscus, anteriorly and prepares for condylar rotation during movement. The rotation occurs through the two condylar heads between the articular disc and the condyle. In addition, the disc provides congruent contours and lubrication for the joint. Gliding, which occurs as a second movement, is a translatory movement of the condyle and disc along the slope of the articular eminence. Both gliding and rotation are essential for full opening and closing of the mouth.

The TMJs actively displace only anteriorly and slightly laterally. When the mouth is opening, the condyles of the joint rest on the disc in the articular eminences, and any sudden movement, such as a yawn, may displace one or both condyles forward. As the mandible moves forward on opening, the disc moves medially and posteriorly until the collateral ligaments and lateral pterygoid stop its movement.

The disc is then “seated” on the head of the mandible, and both disc and mandible move forward to full opening. If this “seating” of the disc does not occur, full range of motion (ROM) at the TMJ is limited. In the first phase, mainly rotation occurs, primarily in the inferior joint space. In the second phase, in which the mandible and disc move together, mainly translation occurs in the superior joint space.

References & More

1. Clinically Oriented Anatomy – 8th Edition
2. Bordoni B, Varacallo M. Anatomy, Head and Neck, Temporomandibular Joint. [Updated 2023 Jul 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: Pubmed
3. Neumann DA: Kinesiology of the musculoskeletal system—foundations for physical rehabilitation, St Louis, 2002