TMD Flashcards
What is the TMJ?
TMJ is a synovial joint.
Articular surfaces - mandibular fossa of temporal bone and condylar head of mandible. This creates a superior and inferior synovial membrane between the articular disc.
The bony surfaces are covered in fibrocartilage.
What are the 3 ligaments of TMJ and their functions?
2 extrinsic:
Sphenomandibular - from spine of sphenoid to lingula of mandible. Primary passive support and acts as fulcrum.
Stylomandibular - from styloid process to angle of mandible (a thickening of the parotid fibrous capsule). No contribution to strength
Intrinsic:
Lateral ligaments of TMJ - formed by thickened part of joint capsule. Strengthens joint and prevents posterior dislocation (along with postglenoid fossa)
What is the blood supple of TMJ?
Deep auricular artery (maxillary artery)
What is the nerve supply of TMJ?
Auriculotemporal, masseteric, posterior temporal nerve.
What are the 3 main causes of TMD?
Myofascial pain
Disc displacement
Degenerative disease
What are less common causes of TMD?
Chronic recurrent dislocation
Ankylosis
Hyperplasia
Neoplasia
Infection
What are the 2 types of disc displacement?
Anterior with reduction (disc slips back)
Anterior without reduction (disc stuck in front of condyle).
What are the 2 types of degenerative disease affecting the TMJ?
Localised -osteoarthritis
Generalised -rheumatoid arthritis (crepitus)
What are the 5 movements of the TMJ?
Protrusion
Retraction
Elevation
Depression
Lateral movements
What muscle is responsible for protrusion?
Lateral pterygoid is responsible for protrusion
What muscle is responsible for retraction of TMJ?
Temporal is is responsible for retraction
In which joint cavity does protrusion and retraction take place?
Superior joint cavity
In which joint cavity does elevation and depression take place?
Elevation and depression take place in the inferior joint cavity
Which muscles are responsible for elevation of TMJ?
Temporalis
Masetero
Medial pterygoid
What is normal opening of TMJ?
30-45 mm