Anatomy of Temporomandibular Joint (TMJ)
- Mandibular head: aka Mandibular condyle
- Mandibular Fossa: on the temporal bone
- Temporal bone has 2 tubercles
- Anterior tubercle (Articular tubercle)
- Posterior Glenoid tubercle
- Articular Disc:
- Divides the joint into 2 joint spaces
- Superior Joint space between disc and mandibular fossa
- Inferior Joint space between disc and mandibular head
- Is bound to mandibular head by many ligaments
Ligaments of TMJ:
- Mechanism of Opening mouth:
- Starts with rotation in the inferior joint space
- Head of the mandible moves on the articular disc
- Very small amount of rotation is not enough to open mouth to full extent.
- Only opens wide enough to make 25 mm of space between teeth
- The remainder of mouth opening
- Requires Translation in which the head of mandible along with the disc glide forward and onto articular tubercle.
- Once on the articular tubercle, have wider range of motion
- The mandibular head has gone anterior to the articular tubercle
- Muscles of mastication go into a spasm
- Mechanism of Closing mouth
- Rotation to start
- Posterior translation
- Rotation once more
- Clinical TMJ:
- the articular disc and head of mandible have become detached
- Causes “clicking” which is where head glides forward / back
- Muscles that move the TMJ:
- Elevation: Medial pterygoid, Masseter & Temporalis.
- Depression: Lateral pterygoid (Most part!) & digastric.
- Protrusion: Lateral and Medial pterygoid, Masseter.
- Retraction: Temporalis, Masseter.
Mnemonic of Innervation of Diaphragm
- Blood supply:
- Superficial temporal artery
- Maxillary artery
- Nerve supply:
- Auriculotemporal nerve
- Masseteric nerve.
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