Temporomandibular joint and the muscles of mastication
- Anatomy and histology
The jaw joint both hinges and slides, with a disc between the bones. Four muscles on each side close the jaw and move it side to side.
See it in 3D: TMJ disc · TMJ capsule · Masseter · Temporalis · Medial pterygoid · Lateral pterygoid · Temporal bones
What it is
The temporomandibular joint (TMJ) joins the mandibular condyle to the temporal bone. A fibrocartilage disc divides it into upper and lower compartments: the lower one hinges (rotation, the first part of opening) and the upper one slides forward onto the articular eminence (translation, wide opening). The muscles of mastication, all supplied by V3, are the masseter, temporalis and medial pterygoid, which close the jaw, and the lateral pterygoid, which pulls the condyle and disc forward to open and move the jaw sideways.
Clinical anatomy
- Condyle, articular disc, articular fossa and eminence of the temporal bone, inside a capsule.
- Masseter and medial pterygoid form a sling around the angle of the mandible.
- Temporalis: closes and retracts the jaw; felt at the temple when clenching.
- Lateral pterygoid: opens, protrudes and moves the jaw to the opposite side.
- Normal mouth opening in adults is about three finger-widths between the incisors.
Clinical correlation
- Temporomandibular disorders cause jaw pain, clicking and limited opening; they are common, usually muscular and usually improve with simple care.
- A click on opening can mean the disc is displaced and slips back into place; a jaw that locks closed suggests the disc no longer reduces.
- Trismus (inability to open) after a dental infection or extraction can be the sign of a spreading deep infection, not a joint problem.
- Jaw pain on chewing in a person over fifty can be claudication of giant cell arteritis.
Next step / Initial management
- Jaw pain with clicking and normal teeth: advise soft diet, warmth, avoiding wide opening and gum chewing, and short courses of simple analgesics; refer if it persists or locks.
- Trismus with fever, swelling or difficulty swallowing: treat as a possible deep neck infection and refer urgently.
- New jaw claudication after fifty: check inflammatory markers and refer urgently for suspected giant cell arteritis.
Test yourself
Think of the answer, then tap the question to see it.
Which muscle of mastication opens the jaw?
The lateral pterygoid, which pulls the condyle and disc forward.
What does a jaw that suddenly locks closed after years of clicking suggest?
Anterior disc displacement that no longer reduces back into place.
Which nerve supplies all the muscles of mastication?
The mandibular division of the trigeminal nerve (V3).
Connections
See it in 3D7
The structures of Durgical's 3D anatomy where it is found.
Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.
Sources: Anatomy, Head and Neck, Temporomandibular Joint (StatPearls Publishing (NCBI Bookshelf), 2025); Anatomy, Head and Neck, Mastication Muscles (StatPearls Publishing (NCBI Bookshelf), 2023); Temporomandibular Syndrome (StatPearls Publishing (NCBI Bookshelf), 2023); TMD (National Institute of Dental and Craniofacial Research (NIDCR, NIH), 2024).
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Representative model, for educational purposes only.