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
What prevents posterior dislocation?
Lateral ligaments of TMJ and postglenoid tubercle
What is the conservative management for TMD?
Counselling - primary habit must be broken
Pain management - analgesics (NSAIDs), muscle relaxants, tricyclic antidepressants, heat pad
Joint rest - soft diet, limited opening, support jaw, chew bilaterally, cut food into small pieces, dont incise food
Physical therapy - slight movements to ensure no adhesions or damage
Restoration of occlusal stability
Bite raising appliance
What is the pathogenesis of TMD?
Inflammation of the muscles of mastication/ TMJ secondary to parafunctional habits.
What are irreversible treatments for TMD?
Occlusal adjustments (rarely done)
TMJ surgery - however, must treat underlying cause
What are urgent signs for referral (with regards to TMD)?
Fever
Weight loss
History of malignancy
Pain rapidly worsening
Numbness
Hearing loss
What are sings/ symptoms of TMD?
Pain (muscular, capsular, intra capsular)
Reduced mobility
TMJ clicking and locking and crepitus
Hypertorphy of muscles of mastication
Tenderness of muscles of mastication
Linea alba
Tongue scalloping
Tooth wear (attrition)
What is the aetiology of TMD?
Multi factorial:
Macro trauma
Micro trauma
Occlusal factors (deep bite, occlusal disharmony, lack of teeth)
Anatomical factors eg class II incisor relationship
What are the 4 basic components of TMJ dysfunction?
- Muscular initiation
- Mechanical TMJ dysfunction
- Psychological underlying cause
- Trauma aetiology (physical or prolonged)
What are the boundaries of the superior joint cavity?
Superior surface of articular disc and inferior surface of glenoid fossa
What are the boundaries of the inferior joint cavity?
Superior surface of the condyle and the inferior surface of the articular disc
What prevents anterior dislocation normally?
The elasticity of the fibres of the bilaminar zone
What causes clicking of TMJ?
Anterior displacement with reduction
Clicking sound when articular disc passes over articular eminence
What causes locked jaw?
Anterior displacement without reduction
what is the first line treatment option for TMJ surgery?
Arthocentesis - release of inflammatory exudate and flush with saline
What are the 7 other TMJ surgery options?
Disc plication
Eminectomy
High condylar shave
Condylotomy
Menisectomy
Condylectomy
Resconstructive procedures
What is an arthogram?
Can be used to image the TMJ
Inject radiopaque dye around condyle in upper and lower joint cavity.
Shows integrity of disc eg. If perforation and if displacement present.
What causes joint dislocation and how is this managed?
If the condyle slips infront of articular eminence
Needs manual reduction
What muscle pulls the articular disc anterior?
Lateral pterygoid
What is arthoscopy? What can be viewed? What is its use?
Scope will show synovial membrane inflammation and degeneration (wont show on radiograph or MRI)
Can only view superior joint cavity.
Can carry out diagnosis, cautery, tissue biopsy, disc reduction, suturing, removal of loose bodies.
What muscles should be palpated for suspected TMD?
Masseter and temporalis
What are the functions of a bite raising appliance?
Eliminates occlusal interferences
Prevents the joint head from rotating so far posteriorly in the glenoid fossa
Reduced loading on the TMJ
