TMJ Flashcards
What does the TMJ consist of?
Glenoid fossa of the temporal bone and the head of the mandibular condyle
what is the purpose of synovial membrane in a typical synovial joint?
-fluid to nourish the articular surfaces to reduce friction, cool the joint, remove waste products
what are the features of a typical synovial joint?
- Capsule to enclose joint/retain fluid
- Ligaments to strengthen joint
- Skeletal muscles to move joint
In a TMJ, what are the articular surfaces made of?
Fibrous tissue
In a TMJ, what is the temporal bone covered in?
periosteum
what is the intra-articular disc made of?
dense fibrous tissue
what is the head of the mandibular condyle covered in?
perichondrium
what lies anteriorly to the TMJ and whats its function?
articular tubercle - prevents anterior dislocation of the TMJ
what lies posteriorly to the TMJ?
post-glenoid tubercle-prevent posterior dislocation of the TMJ
what aids the post glenoid tubercle in preventing posterior dislocation?
ligaments
Where does the lateral pterygoid attach?
pterygoid fovea
What nerve goes through the mandibular foreman?
Inferior alveolar nerve
where is the retro-molar triangle?
Bind the 3rd molar
What is the role of the lateral temporomandibular ligament ?
Stabilising and prevent posterior sublaxation (partial dislocation) and dislocation
What does the joint capsule do?
attaches around the circumference of the articular surfaces and keeps synovial fluid in its joint
where is the stylomandibular ligament?
styloid process to medial aspect of angle of mandible
where is the sphenomandibular ligament and whats its function?
spine of sphenoid to lingual of mandible and it prevents over opening of jaw
where is the pterygomandibular raphe and whats his function?
pterygoid hamulus to retromolar triangle and prevents over opening
what is the function of the intra-articular disc?
provides stability of the joint during movement by improving the fit between the bony articulating surfaces
what is the disc made of?
dense fibrous connective tissue
what does the anterior extension of the disc attach to?
continuous with the joint capsule anteriorly and with the tendon of the lateral pterygoid muscle
what are the 2 layers of the posterior extension?
- upper layer contains elastic fibres (assist with return of disc to resting position)
- inferior tale- rich blood supply- during jaw opening
what happens during jaw opening to fill the space?
both upper and lower layers contain vascular tissue (engorge with blood on opening and empties into pterygoid venous plexus on closing – adapt shape of disc to space available within joint capsule
What are the 3 bands of the disc proper?
- anterior band (thick – 3mm)
- intermediate zone (thin - 1mm)
- posterior band (thick – 3mm)
what are the join spaces and what are they lined by?
- upper and lower
- lined by its own synovial membrane
what happens during initial jaw opening?
anterior rotation of head of condyle
movement occurs in the lower joint space
the disc remains in place
what happens during full jaw opening?
disc then translates (slides) anteriorly articulating with the mandibular fossa and articular eminence
the movement occurs in the upper joint space
what is the name for a clicking jaw?
internal derangement with reduction
what happens during internal derangement with reduction?
- Disk displacement with reduction typically causes clicking and pain with chewing
- Internal derangement is associated with stretching of the posterior extension
what is the nerve supply to the TMJ?
auricolotemporal nerve
what happens during dislocation of the TMJ?
- occurs when the mandibular condyle becomes fixed in the anterosuperior aspect of the articular eminence
- Spasm of the masseter, temporalis, and internal pterygoid muscles results in trismus, preventing return of the condyle to the temporal fossa
what is the movement of jaw opening?
initial anterior rotation (hinge - lower joint space)
subsequent anterior translation (slide - upper joint space)
maximum normal opening equivalent to
what is the movement of jaw closing?
initial posterior translation (upper joint space)
subsequent posterior rotation (lower joint space)
