The TMJ articulation is located on the squamous portion of the temporal bone

Has an avascular articular surface composed primarily of fibrous connective tissue and some fibrocartilage instead of hyaline cartilage

The main load-bearing areas are on the lateral aspect of the squamous portion, condyle, and articular disc

The dense fibrous connective tissue is thickest in the load-bearing areas

Relations of the squamous portion of the temporal bone:

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  Anterior—articular eminence

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  Intermediate—glenoid fossa

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  Posterior—tympanic plate tapering to the postglenoid tubercle

The depression into which the condyle is located

Superior to this thin plate of bone is the middle cranial fossa

The anterior boundary of the glenoid fossa is the articular eminence

The posterior boundary of the glenoid fossa is the tympanic plate

The glenoid fossa can be divided into 2 parts by the squamotympanic fissure (lateral) and the petrotympanic fissure (medial):

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  Anterior articular area—squamosal part of the temporal bone (this is where the articulation occurs)

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  Posterior nonarticular area—tympanic portion (parotid gland may extend into this area)

An inferior extension of the squamous portion of the temporal bone

Makes the posterior aspect of the glenoid fossa

Provides attachment for the capsule and retrodiscal pad

Articulate with the articular disc

Ovoid in shape:

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  Mediolateral—20 mm

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  Anteroposterior—10 mm

Articular surface is avascular fibrous connective tissue instead of hyaline cartilage

The main load-bearing areas are on the lateral aspect

Composed of dense fibrous connective tissue

Located between the squamous portion of the temporal bone and the condyle

Is avascular and aneural in its central part but is vascular and innervated in the peripheral areas, where load-bearing is minimal

The main load-bearing areas are located on the lateral aspect; this is an area of potential perforation

Merges around its periphery, attaching to the capsule

Divided into 3 bands:

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  Anterior—this thick band lies just anterior to the condyle with the mouth closed

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  Intermediate—this band, the thinnest part, is located along the articular eminence with the mouth closed

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  Posterior—this thick band is located superior to the disc with the mouth closed

Additional attachments:

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  Medial/lateral—strong medial and lateral collateral ligaments anchor the disc to the condyle

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  Anterior—the disc is attached to the capsule and the superior head of the lateral pterygoid, but not the condyle, allowing the disc to rotate over the condyle in an anteroposterior direction

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  Posterior—the disc is contiguous with the bilaminar zone that blends with the capsule

A bilaminar structure located posterior to the articular disc

Highly distortable, especially on opening the mouth

Composed of:

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  Superior lamina (stratum)—contains elastic fibers and anchors the superior aspect of the posterior portion of the disc to the capsule and bone at the postglenoid tubercle and tympanic plate

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  Retrodiscal pad—the highly vascular and neural portion of the TMJ, made of collagen, elastic fibers, fat, nerves, and blood vessels (a large venous plexus fills with blood when the condyle moves anteriorly)

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  Inferior lamina (stratum)—contains mainly collagen fibers and anchors the inferior aspect of the posterior portion of the disc to the condyle