13. Temporo-mandibular joint

Covers the temporo-mandibular joint, starting with its definition and type as a synovial, modified hinge joint with gliding and rotational movements. It then describes the articular surfaces on the temporal bone and mandible, the biconcave articular disc that divides the cavity into two compartments, and the thin fibrous capsule. The three ligaments are set out with their attachments and functions, followed by the joint's relations, blood supply and nerve supply. Two pictures accompany the text.

Inside: 9 sections · 2 labelled pictures · 11 flashcards · 2 min

Topic 13 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 9 sections, about 225 words (2 min of reading), with 11 flashcards.

Definition & Type

TMJ = articulation between the mandible and the temporal bone.
Type: Synovial, modified hinge joint (ginglymoarthrodial).
Functions as a hinge joint (depression & elevation).
Also has gliding & slight rotational movements → therefore more complex than a simple hinge.

Articular Surfaces

1. On temporal bone:

Mandibular fossa (shallow, in squamous temporal bone).
Articular tubercle (anterior bony projection).

2. On mandible:

Head of mandible (condylar process).

Articular Disc

Fibrocartilaginous, biconcave shape.
Divides joint cavity into upper and lower compartments:
Upper compartment → gliding movements (translation: protrusion & retraction).
Lower compartment → hinge movements (rotation: depression & elevation).
Attached around capsule, blends with lateral pterygoid tendon (anteriorly).

Fibrous Capsule

Thin, loose → allows wide movements.
Attached:
Above → margins of mandibular fossa and articular tubercle.
Below → neck of mandible.

Ligaments

1. Lateral (temporomandibular) ligament

Strong band, thickened lateral part of capsule.
Runs from zygomatic arch → lateral neck of mandible.
Function: prevents posterior dislocation.

2. Sphenomandibular ligament (accessory)

From spine of sphenoid → lingula of mandible.
Function: acts as passive support.

3. Stylomandibular ligament (accessory)

From styloid process → posterior border of ramus/angle of mandible.
Function: checks excessive protrusion.