The only freely movable joint of the skull, apart from the tiny joints of the middle-ear bones
Temporomandibular joint — between mandible and temporal bone.
Anatomy · Joints & cartilage
Temporomandibular joint
The joint of the jaw
Head · skull and mandible
The temporomandibular joint (TMJ) is the articulation between the condyle of the mandible and the mandibular fossa of the temporal bone, just in front of the ear. A fibrocartilage articular disc divides it into two compartments. Opening the mouth needs both a hinge movement and a forward glide, and because the jaw is a single bone, the two joints always work together.
How to spot them
- ▸You can feel it moving with a finger just in front of the tragus of the ear when you open your mouth
- ▸The mandibular condyle sits in the mandibular fossa, and glides forward onto the articular tubercle when the mouth opens
- ▸A fibrocartilage disc splits the joint cavity into upper and lower compartments
- ▸Lateral pterygoid pulls the condyle forward; masseter and temporalis close the jaw
What to know
Opening the mouth needs a hinge and a glide together, with a fibrocartilage disc travelling with the condyle
Temporomandibular joint — the articular disc.
Yawning too wide can dislocate it, with the condyle sliding in front of the articular tubercle
Temporomandibular joint — anterior dislocation, with the mouth locked open.
Clicking, pain and locking of the jaw, often linked to grinding of the teeth (bruxism)
Temporomandibular joint — temporomandibular disorder.
Both sides must work together because both are ends of a single U-shaped bone
Temporomandibular joint — the mandible.
Key ideas
- One bone, two joints: the mandible moves as a unit, so a problem on one side affects the other.
Quick-fire facts
- •It is a synovial joint that combines gliding and hinge movements (OpenStax).
- •The disc divides the joint cavity into an upper (gliding) compartment and a lower (hinge) compartment.
- •The condyle of the mandible articulates with the mandibular fossa and articular tubercle of the temporal bone.
- •The lateral pterygoid is the main muscle that opens the mouth (with gravity and the suprahyoid muscles); masseter, temporalis and medial pterygoid close it.
- •The mandible is the only freely movable bone of the skull, if the ear ossicles are excluded.
- •TMJ disorders may arise from arthritis, teeth grinding, damage to the disc or jaw injury.
- •The joint is innervated mainly by the auriculotemporal and masseteric branches of the mandibular nerve, which explains ear pain from jaw disease.
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