TMJ 100 Facts Flashcards
What are considered to be the accessory ligaments of the TMJ?
- Sphenomandibular lig
- Stylomandibular lig
What is the function of the accessory ligaments of the TMJ?
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 IAN block?
Sphenomandibular Lig
Where does the temporomandibular ligament run?
From the articular eminence to the mandibular condyle
What are the 3 functions of the temporomandibular lig?
- Provides lateral reinforcement
- Prevents posterior and inferior displacement of condyle
- Main stabilizing ligament
What is another name for the temporomandibular ligament?
Lateral ligament
What is another name for the 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 made from?
Collagenous connective tissue, Do Not Stretch
Which muscle will cause a deviation of the mandible to the damaged side when protruding?
Lateral Pterygoid
What are the 2 parts of the lateral pterygoid muscle?
Superior and Inferior belly
Where does the inferior belly of the lateral pterygoid run?
From lateral pterygoid plate to the neck of the condyle
Where does the superior belly of the lateral pterygoid run?
Greater wing of the sphenoid and infratemporal crest
Inserts on joint capsule, articular disk and condyle of the neck
What is the function of the superior belly of the lateral pterygoid?
Assit 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 the mandible (jaw closing)
- Retraction of the mandible (lower jaw backward)
What is the function of the medial pterygoid?
Elevation of the mand. (jaw closing)
What is the function of the inferior belly of the lateral pterygoid?
Slight depression of the mandible
What occurs with unilateral contraction of the lateral pterygoids?
Lateral deviation of the mandible
What occurs with bilateral contraction of the lateral pterygoids?
Protrusion of the mandible
Where do you test a pts TMJ tenderness and noise?
Joint palpated laterally over the posterior surface of the condyles with the mouth open.
Condyles are not symmetrical nor identical, True or False?
True
Dislocation of the TMJ is almost always … and occurs while …
Anteriorly
Laughing or yawning
What is dislocation also referred to as?
Open lock
Hypertranslation or hypermobility of the mandible is called?
Subluxation
Which component of the TMJ has the most vasculature and innervation?
Retrodiscal Tissue
omposed of dense fibrous connective tissue, and is positioned in between the condyle and the fossa, dividing the joint into superior and inferior spaces?
Articular Disk
What is the middle part of the articular disk called?
Thinner central intermediate zone
Which band, anterior or posterior, is the thicker of the two on the articular disk?
Posterior
What kind of tissue is attached to the posterior articular disk?
Retrodiscal tissue
What is attached/contiguous to the anterior band of the articular disk?
- Capsular ligament
- Condyle
- Superior belly of the Lateral Pterygoid
What are the articular surfaces of the TMJ covered with?
dense fibrous CT
What does the layer of fibrocartilage tissue provide to the TMJ?
Resistance against both compressive and lateral forces
What is the shape of the Condyle?
Eliptical, long axis oriented mediolaterally
What test is the gold standard test to provide an image of the soft tissue of the TMJ, esp. the position of the articular disc?
MRI
What is the major advantage of the MRI?
No exposure of the pt 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 of the TMJ usually assocaited with?
Degenerative process (osteoarthritis) of the condyle
What is a dull thud in the TMJ usually associated with?
Self-reducing subluxation of the condyle
A patient has clicking in their TMJ, where is the joint most likely to be displaced?
Anteromedial
What occurs during disc displacement of the TMJ?
Collateral ligaments become elongated/torn, which allows the lateral pterygoid to pull the 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 and sliding
What is considered to be the nonfunctioning portion of the TMJ?
Articular fossa (ant 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 CT on its articular surfaces?
TMJ
What vessesl supply the TMJ?
- Deep temporal and Masseteric a. branches of Maxillary a.
- Branches of superficial temporal from ECA
What is the venous drainage of the TMJ?
Superficial temporal, maxillary, and pterygoid plexus
What is the capsule of the TMJ innervated by?
Auriculotemporal n. (V3)
What is the anterior region of the TMJ innervated by?
Masseteric and Deep Temporal (V3)
Sensory from V3
What path fo the nerve fibers that innervate the TMJ follow?
Vessesl of the blood supply
End as free nerve endings
What part of the TMJ are not innervated?
articular cartilage and 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 fo the TMJ is fairly thin except where?
Laterally where it forms the temporomandibular ligament (lateral)
Where is the fibrous capsule of the TMJ firm? Why?
- Medially and Laterally
- Stabilize mandible during movement
Where is the fibrous capsule of the loose?
Anterior and Posterior
To allow mandibular movement
What are large amounts of synovial fluids an indication of in the TMJ?
Painful internal derangements
What is the purpose of the joint capsule and ligaments of the TMJ?
Restrict excessive displacement of the mandible
What is the thicker layer of fibrous tissue which is reinforced by accessory ligaments?
Outer fibrous layer of the fibrous capsule of the TMJ
Translatory movements take place in which compartment of the TMJ?
Upper
Mandibular fossa - articular disc
Rotary motions take place in which compartment of the TMJ?
Lower compartments
- Condyle - articular disc*
- Hinge type rotation*
With the fracture of condylar neck, why does the condylar head remain in the mandibular foss?
Due to TMJ Ligament (main stabilizing lig.)
Restricts the downward and posterior movement of the mandible and guides the forward motion fo the condyle dueing opening
The mandible will always deviate to the side of injury?
True
Closing the mouth / elevation of the mandible results from bilateral contraction of which 3 muscles?
- Anterior fibers (verticle fibers) of Temporalis
- Masseter
- Medial pterygoid
Retrusion of the jaw results from the bilateral contraction of?
Posterior fibers (horizontal) of the Temporalis
Anterio-inferior aspect of hte mandibular condyle is?
Concave
Posterior aspect of mandibular condyle is?
Rounded and convex
Is the central portion of the articular disc vascular?
Avascular and lack of innervation at central portion of the articular disc
Which belly of the lateral pterygoid inserts on the neck of the condyle?
inferior belly
When can dislocation of either or both TMJs occur?
When the condyle translates anterior to the crest of the articular eminence
Most stable and easily reproduced position?
Centric Relation
Initiating position
Which movements are the limits to which the mandible can move?
Border movements
Which movements generally occur within border movements?
Functional movements
Which jaw position is ligament guided?
Centric Relation
In protrusive movements, the condyles of the mandible have moved in which direction?
Downward and forward
Which movement requires the condyles to move bacwards and upward?
Retrusive movement
Anterior guidance 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
What is the muscle guideds position?
Rest position of the mandible or postural position
What is the tooth guided position?
Centric Occlusion