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Questions and Answers
What structure separates the articulating surfaces of the temporomandibular joint?
What structure separates the articulating surfaces of the temporomandibular joint?
Which muscle is primarily responsible for the retraction of the mandible?
Which muscle is primarily responsible for the retraction of the mandible?
What type of cartilage covers the articular surfaces of the bones in the temporomandibular joint?
What type of cartilage covers the articular surfaces of the bones in the temporomandibular joint?
Which movements are permitted by the upper part of the temporomandibular joint?
Which movements are permitted by the upper part of the temporomandibular joint?
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What is the primary artery supplying the temporomandibular joint?
What is the primary artery supplying the temporomandibular joint?
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Which muscle assists in depressing the mandible if there is resistance?
Which muscle assists in depressing the mandible if there is resistance?
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What can cause dislocation of the temporomandibular joint?
What can cause dislocation of the temporomandibular joint?
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What is the main function of the lower part of the temporomandibular joint?
What is the main function of the lower part of the temporomandibular joint?
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Study Notes
Temporomandibular Joint (TMJ) Anatomy
- The TMJ is a synovial joint formed by the mandible and temporal bone.
- It's located in front of the ear, on the side of the face.
- The joint's articulating surfaces include the mandibular fossa and articular tubercle (temporal bone) and the head of the mandible.
TMJ Structure and Function
- The joint has a unique structure: an articular disc separates the bones, creating two synovial cavities.
- The surfaces of the bones are covered with fibrocartilage, not hyaline cartilage.
TMJ Movements
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Protrusion/Retraction: The upper part of the joint.
- Protrusion is driven primarily by the lateral pterygoid (and medial pterygoid).
- Retraction is facilitated by the posterior temporalis muscle fibres.
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Elevation/Depression: The lower part of the joint.
- Depression is primarily gravity-assisted.
- Muscles like the digastric, geniohyoid, and mylohyoid aid with depression against resistance.
- Elevation is a more forceful movement, caused by the temporalis, masseter, and medial pterygoid muscles.
TMJ Blood Supply and Innervation
- Blood supply comes from branches of the external carotid artery (superficial temporal, deep auricular, ascending pharyngeal, and maxillary branches).
- Innervation is via the auriculotemporal and masseteric branches of the mandibular nerve (CN V3).
Clinical Relevance: TMJ Dislocation
- Dislocations can happen due to facial blows, yawning, or forceful biting.
- The mandible head "dislocates" out of the mandibular fossa, pulling forward.
- This makes it difficult to close the mouth.
- Facial and auriculotemporal nerves may be injured in severe dislocations.
- Posterior dislocations are extremely rare and usually require significant force to pass the postglenoid tubercle and overcome strong intrinsic ligaments.
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Description
Explore the intricacies of the Temporomandibular Joint (TMJ), which plays a crucial role in jaw movement. This quiz covers the anatomy, structure, and function of the TMJ, including its movements like protrusion, retraction, elevation, and depression. Test your knowledge on this vital anatomical feature of the head.
