TEMPOROMANDIBULAR JOINT
Temporomandibular joint
- Type
- Synovial
- Condylar type
- Articular surfaces
- Upper articular surfaces :
- Articular tubercle
- Anterior part of mandibular fossa
- Posterior non articular part formed by tympanic plate
- Inferior articular surface is formed by head of mandible
- Coverings
- Covered with fibrocartilage
- Cavity
- Joint cavity divided by intraarticular disc
- Upper and
- Lower part
- Ligaments
- Fibrous capsule
- Attached
- Above to articular tubercle , circumference of mandibular fossa infront and squamotympanic fissure behind
- Below
- Neck of mandible
- Capsule
- Loose above intra articular disc and tight below it
- Synovial membrane lines the fibrous capsule and neck of mandible
- Lateral temporomandibular ligament
- Reinforces and strengthens lateral part of capsular ligament
- Fibres directed downwards and backwards
- Attached
- above to articular tubercle
- Below to posterolateral aspect of neck of mandible
- Sphenomandibular ligament
- Accesory ligament
- Lies in a deep plane away from fibrous capsule
- Attached superiorly to spine of sphenoid
- Inferiorly to lingula of mandibular foramen
- Remnant of meckels cartilage
- Relations.
- Medial
- Chorda tympani nerve
- Wall of pharynx
- Lateral
- Lateral pterygoid muscle
- Auriculotemporal nerve
- Maxillary artery
- Stylomandibular ligament
- Accesory ligament of the joint
- Thickened part of deep cervical fascia
- Separates parotid and submandibular salivary glands
- Attached above to lateral surface of styloid process
- Below to angle and adjacent part of posterior border of ramus of mandible
- ARTICULAR DISC
- oval fibrous plate
- Upper compartment
- Gliding
- Lower compartment
- Rotatory and gliding
- Surface
- Concavo convex superior surface
- Concave inferior surface
- Attachment
- Periphery attached to fibrous capsule
- Disc
- Anterior extension
- Anterior thick band
- Intermediate zone
- Posterior thick band
- Bilaminar region
- Represents degenerated primitive insertion of lateral pterygoid
- Function
- Prevents friction between articulating surface
- Acts as a cushion , helps in shock absorption
- Stabilises condyle by filling up space between articulating surface
- RELATIONS OF TMJ
- Lateral
- Skin and fascia
- Parotid gland
- Temporal branches of facial nerve
- Medial
- Tympanic plate separates the joint from internal carotid artery
- Spine of sphenoid with upper end of sphenomandibular ligament
- Auriculotemporal and chorda tympani nerves
- Middle meningeal artery
- Anterior
- Lateral pterygoid
- Masseteric nerve and artery
- Posterior
- Parotid gland separates joint from external auditory meatus
- Superficial temporal vessels
- Auriculotemporal nerve
- Superior
- Middle cranial fossa
- Middle meningeal vessels
- Inferior
- Maxillary artery
- Maxillary vein
- BLOOD SUPPLY
- NERVE SUPPLY
- MOVEMENTS
- depression ( open mouth )
- Elevation ( closed mouth )
- Protrusion ( protraction of chin )
- Retrusion ( retraction of chin )
- Lateral or side to side movements ( chewing or grinding )
| Articular surfaces | Temporal bone: Mandibular fossa and articular tubercle | |
| Mandible: Condylar process | ||
| Main components | Joint capsule | |
| Synovial membrane | Synovial membrane | |
| Articular disc (anterior/posterior bands, intermediate zone) | ||
| Ligaments | Major: Lateral temporomandibular ligament (thickened lateral portion of capsule, strengthens TMJ laterally) | |
| Minor: Stylomandibular ligament, sphenomandibular ligament | ||
| Cavities | Superior (discotemporal) cavity (translational movement) | |
| Inferior (discomandibular) cavity (rotational movement) | ||
| Rotational movements | Elevation: Temporalis, masseter and medial pterygoid muscles | |
| Depression: Lateral pterygoid, digastric, geniohyoid and mylohyoid muscles | ||
| Translational movements | Protrusion: Lateral pterygoid, medial pterygoid muscle, masseter | |
| Retraction: Posterior fibers of temporalis, deep part of masseter | ||
| Lateral deviation (left or right): Posterior fibers of temporalis, digastric, mylohyoid and geniohyoid muscles (ipsilateral movement); lateral and medial pterygoid muscles (contralateral movement) |
ARTICULAR SURFACES
LIGAMENTS
- fibrous capsule
- lateral temporomandibular ligament – articular tubercle –> neck of mandible
- Sphenomandibular ligament - spine of sphenoid –> lingula of mandibular foramen
- stylomandibular ligament - lateral surface of styloid process