Infratemporal Fossa II Flashcards
What is within the synovial joint? What is each of the structures function?
- Synovial membrane (for lubrication)
- Articular cartilage (to withstand loads)
- Joint cavity (for free movement)
- Articular disc (shock absorber)
- Fibrous capsule (for joint integrity)
- Also contains ligaments (for stability)
What is the type of cartilage in the TMJ?
fibrocartilage
The TMJ forms adjacent to the
intramembranous bone
what makes up the joints of the body structure of the TMJ?
Mandibular condyle & fossa
What are structures surrounding the TMJ?
Postglenoid spine, articular eminence, articular tubercle
What are the ligaments associated w/ the TMJ?
Lateral ligament, sphenomandibular ligament, stylomandibular ligament
Where does the lateral ligament attach? Is it strong or weak?
Attaches to posterior end of zygomatic arch (specifically to the articular tubercle)
It’s the strongest of the 3 ligaments
Location of the sphenomandibular ligament? What’s its function? Is it strong or weak?
Runs from sphenoid spine to lingula of mandible
Plays a minimal role in limiting mandibular movement b/c it doesn’t extend w/ mandibular movement
It’s the 2nd weakest of the 3 ligaments
Location of the stylomandibular ligament? What’s its function? Is it strong or weak?
Runs from styloid process to inferior aspect of mandible
Limits excessive protrusive movement of mandible
It’s the weakest of the 3 ligaments
Where’s the synovial membrane present?
Located in the folds of the joint cavity, where no friction occurs
What are the 2 basic cell types that form the synovium? What’s their function?
Synoviocytes
- Production of synovial fluid, which lubricates joint surfaces & nourishes chondrocytes
Synovial cells
- Phagocytosis, degradation, & removal of debris in joint cavity
Anterior & posterior attachment of the articular disc
Attachment anteriorly: to superior head of lateral pterygoid plate
Attachment posteriorly: neck of condyle inferiorly & glenoid spine
What are the different regions within the articular disc?
anterior band, posterior band, & intermediate zone between the 2
The bilaminar zone (retrodiscal pad) is sandwiched between ___. What’s its function?
superior & inferior lamina
Facilitates great exchange of fluids & production of synovial fluid by synovial membrane
Function of the superior & inferior lamina
Superior lamina
- Allows the disk & condyle to travel far
- contains elastic fibers
Inferior lamina
- Contains collagen
- Limits anterior sliding of disk along condyle
Are the bilaminar zone & the disc vascular?
Bilmaniar zone is vascular
Disc is avascular
At full opening, the pad is expanded ___ times its jaw closed volume
4-5
Blood supply to the TMJ comes from the
superficial temporal artery
What are the sources of innervation to the joint? Where do they supply to?
Masseteric nerve (supplies anterior aspect of TMJ) & auriculotemporal nerve (supplies posterior aspect of TMJ)
Does the disk have innervation?
no
R & L TMJs are connected to each other by the
mandible
What muscle acts to produce movements of the TMJ?
lateral pterygoid muscle (superior & inferior head)
Describe movement of the articular disc during opening/closing movements of the lower jaw in relation to the lateral pterygoid muscle
- When inferior head contracts, it pulls the condyle superiorly
- When superior head contracts, it pulls the disk forward
What are the 2 types of movements at the TMJ?
- Rotation of condyle (hinge) & jaw drops - Up down rotation of condyle relative to the disk
- Translation (sliding) - Disk slides (w/ condyle) back & forth that’s facilitated by lateral pterygoid muscle
Mechanical displacement of the articular disk results in
abnormal relationship of the disk to the condylar head & articular eminence
- Disk is located anterior to condyle head
Describe anterior disk displacement
posterior band of the disc located anterior to the superior portion of the condyle at closed mouth on oblique sagittal images
Describe anterior displacement w/ reduction & w/o reduction
w/ reduction = opened mouth position disc may be in a normal position
- you hear a “click” sound
w/o reduction = continue to be displaced
Describe posterior disk displacement
condyle slides anteriorly to anterior eminence
Sounds in TMJ occur in ___ of the population & pain is in ___ of the population. Are they more common in men or women?
30-50%
6-12%
women (4:1 to 6:1)
When the mouth is closed, where is the disk in relation to the condyle?
Resting above the condyle
Forces are transmitted to the ___ during chewing & biting
Condyle
