100 Facts of TMJ Flashcards
What are considered to be the accessory ligaments of the TMJ?
- Sphenomandibular ligament
- Stylomandibular ligament
What is the function of the Sphenomandibular ligament + stylomandibular ligament?
Limit excessive openings
Where is the sphenomandibular ligament attached?
Lingula of the mandible
Where does the stylomandibular ligament attach?
Angle of the mandible
What ligament is most damaged when using an inferior alveolar nerve block?
Sphenomandibular ligament
Where does the temporomandibular ligament run?
From the articular eminence to the mandibular condyle
What are the (3) functions of the temporomandibular ligament?
- Provides lateral reinforcement
- Prevents posterior and inferior displacement of condyle
- Main stabilizing ligament
What is another name for temporomandibular ligament?
Lateral ligament
What is another name for collateral ligaments?
Discal ligaments
Where does the collateral ligaments run?
Arise from the periphery of the disc and are attached to the medial and lateral poles of the condyle
What is the function of the collateral ligaments?
- Stabilize the disc on top of the condyle
- Resist movements of disc away from condyle during function
What are collateral ligaments (discal ligaments) made from?
Collagenous connective tissue – it does not stretch
Which muscle will cause a deviation of the mandible when protruding to the side of the damage?
Lateral pterygoid
What are the two parts of the lateral pterygoid?
Superior belly and inferior belly
Where does the inferior belly of the lateral pterygoid run?
From lateral pterygoid plate to neck of condyle
Where does the superior belly of the lateral pterygoid run?
Greater wing of the sphenoid & infratemporal crest
Where does the superior belly of the lateral pterygoid insert?
Inserts on joint capsule, articular disk and condyle of neck
What is the function of the superior belly of the lateral pterygoid muscle?
Assist in stabilizing the position of the articular disk during closing
What is the function of the masseter?
Elevation of the mandible (jaw closing)
What is the function of the temporalis?
- Elevation of mandible (jaw closing) anterior fibers (run vertical)
- Retraction of the mandible (lower jaw backward) posterior fibers (run horizontally)
What is the function of the medial pterygoid?
Elevation of the mandible (jaw closing)
What is the function of the inferior heads of the lateral pterygoid?
Slight depression of the mandible (jaw closing)
What occurs with unilateral contraction of the lateral pterygoids?
Lateral deviation of mandible
What occurs with bilateral contraction of the lateral pterygoid muscles?
Protrusion of the mandible
Where do you test a patient’s temporomandibular joint tenderness and noise?
Joint palpated laterally over the posterior surface of the condyles with the mouth open
TRUE OR FALSE:
Condyles are not symmetrical nor identical.
True
Dislocation of the TMJ is almost always? ___
It happens during? ___ or ____
- Anteriorly
- Laughing or yawning
What is dislocation also referred as?
Open lock
Hypermobility or hypertranslation of the mandible?
Subluxation
What is the difference between dislocation and subluxation?
With subluxation patient can return the mandible to its normal position without assistance
of the dentist
Which component of the TMJ has the most vasculature and innervation?
Retrodiscal tissue
Articular disc is composed of ____ fibrous connective tissue.
dense
Articular disc is positioned in between the:
condyle and the fossa
Articular disc divides the joint into:
superior and inferior spaces
What is the middle part of the articular disk called?
Thinner central intermediate zone
Which band is the thicker of the two on the articular disk? Anterior or posterior?
Posterior
What kind of tissue is attached to the posterior articular disk?
Retrodiscal tissue
What are the articular surfaces of the TMJ covered with?
Dense fibrous connective tissue
What does the layer of fibrocartilaginous tissue provide to the TMJ?
Offers resistance against both compressive and lateral forces
What is the shape of the condyle?
Elliptically shaped long axis is oriented mediolaterally
What test is considered to be the gold standard for providing an image of the soft tissue of the TMJ, especially the position of the articular disc?
MRI
What is the major advantage of the MRI technique?
No exposure of the patient to x-ray radiation
What sound is made by the articular disc when displaced to the anterior of the condyle?
Clicking
What is a crepitation sound or a crepitus in the TMJ usually associated with?
Degenerative process (osteoarthritis) of the condyle
What is a dull thud in the TMJ usually associated with?
Self-reducing subluxation of the condyle
What is another term for ear ringing?
Tinnitus
A patient has clicking in their TMJ where is this joint most likely to be displaced?
Anteromedial
What occurs during disc displacement of the TMJ?
- Collateral ligaments become elongated/torn.
* Allows lateral pterygoid to pull articular disc out of place
What type of joint is the TMJ?
Ginglymoarthroidal joint
What type of movements does the TMJ allow?
Hinge like rotation & sliding
What is considered to be the nonfunctioning portion of the TMJ?
Articular fossa (anterior 3/4 of large mandibular fossa)
What is considered to be the functional part of the TMJ?
Articular eminence
What is it that connects the mandible to the temporal bone?
Combined hinge and gliding joint
What is the only movable joint in the skull that has dense fibrous connective tissue on its articular surfaces?
TMJ
The vessels that supplies the TMJ?
- Deep temporal and masseteric of maxillary artery
* Branches of superficial temporal from external carotid
What is the venous drainage of the TMJ?
- Superficial temporal vein
- Maxillary vein
- Pterygoid plexus
What is the capsule of the TMJ innervated by?
Auriculotemporal nerve (V3)
What is the anterior region of the TMJ innervated by?
- Masseteric and deep temporal from V3
* Sensory from V3
What path do the nerve fibers that innervate the TMJ follow?
- Vessels of the blood supply
* End as free nerve endings
What parts of the TMJ are not innervated?
Articular cartilage & central part of the articular disc
Are myelinated or unmyelinated nerves seen in the TMJ?
Both
What is the source of proprioception in the TMJ?
Retrodiscal tissue
What structure of the TMJ secretes the fluid that lubricates the TMJ?
Inner synovial layer of fibrous capsule
The fibrous capsule of the TMJ is fairly thin except where?
Laterally where it forms the temporomandibular ligament (lateral)
Where is the fibrous capsule of the TMJ firm? ___ and ___
Why?
Medially and laterally
It stabilizes mandible during movement
Where is the fibrous capsule of the TMJ loose? ___ and ___
Why?
Anterior and posterior
Allow mandibular movement
Large amounts of synovial fluids in the TMJ an indication of?
Painful internal derangements
What is the purpose of the joint capsule and ligaments of the TMJ?
Restrict excessive displacement of the mandible
Thicker layer of fibrous tissue which is reinforced by accessory ligaments?
Outer fibrous layer of the fibrous capsule of the TMJ
Translation take place in which compartment of the TMJ?
Upper compartment (mandibular fossa - articular disc)
Rotation take place in which compartment of the TMJ?
Lower compartments (condyle - articular disc) - hinge-type rotation
TRUE OR FALSE:
The mandible will always deviate to the side of injury.
True
Retrusion of jaw results from the bilateral contraction of?
Bilateral contraction of posterior fibers (horizontal fibers) of the temporalis muscle.
Anteroinferior aspect of mandibular condyle is ____?
Concave
Posterior aspect of mandibular condyle is ____?
Rounded & convex
Do central portion of articular disc is vascular?
Avascular & lack of innervation at central portion of articular disc
Nonfunctional part of TMJ?
Articular fossa
Functional part of TMJ?
Articular eminence/articular tubercle
_______belly of lateral pterygoid inserts on the neck of the condyle?
Inferior belly
Dislocation of either or both TMJ can occur?
When the condyle translates anterior to the crest of the articular eminence
Pure rotation of mandible involves which two planes of movement?
- Frontal plane - up and down
* Sagittal plane - forward & backward
Most stable & most easily reproduced position?
Initiating position (centric relation)
The maximum opening movement of mandible depending on the age and size?
50-60mm
Which movements are the limits to which mandible can move?
Border movements
Which movements generally occur within the border movements?
Functional movements
Which jaw position is ligament guided position?
Centric relation
In protrusive movements, the condyles of mandible have moved in which direction?
Downward & forward direction
Which movement require condyles to move backward and upward?
Retrusive movement
Anterior guidance/anterior coupling is determined by?
- Overbite
* Overjet
Anterior guidance is the guidance provided by the anterior teeth when the mandible goes into a _____ movement?
Lateral or protrusive movement
Muscle guided position?
Rest position of mandible or postural position.
Tooth guided position?
Centric occlusion / intercuspal position