MOM and TMJ Flashcards
where is the TMJ?
between the mandibular fossa of temporal bone and condylar process of mandible
what type of joint in the TMJ?
modified hinge synovial joint
what are the articular surfaces of the bone covered with?
fibrocartilage
why does the TMJ have fibrocartilage?
the TMJ has a lot of forces applied so it helps to deal with these forces and pressure
what separates the joint into upper and lower joint cavities?
fibrocartilaginous articular disc
TMJ ligaments
2 extrinsic : -sphenomandibular ligament
- stylomandibular ligament
1 intrinsic : lateral ligament
sphenomandibular ligament - position and function
-runs from spine of the sphenoid to the mandible, is posterior to the mandible
- provides primary passive support to the mandible
stylomandibular ligament - position
runs from styloid process to the mandible
lateral ligament - function
-Strengthens TMJ laterally
-With postglenoid tubercle prevent posterior dislocation
why is anterior dislocation of TMJ more likely than posterior dislocation?
postglenoid tubercle (with help from lateral ligament) prevents posterior dislocation
4 muscles of mastication
temporalis
masseter
medial pterygoid
lateral pterygoid
4 MOMs are derivatives of what?
1st pharyngeal arch
temporalis - action and innervation
- retracts and elevates mandible (closing mouth) , lateral movements (side to side)
-innervated by deep temporal nerves from anterior trunk of CN V3
masseter - action and innervation
- elevates mandible and protrudes mandible
- innervated by masseteric nerve from the anterior trunk of CNV3
medial pterygoid - position, action and innervation
- situated posterior to mandible, has deep and superficial head
- elevates mandible and assists with lateral movement (side to side)
- innervated by nerve to medial pterygoid from the main trunk of CNV3
(only MOM innervated by main trunk of CNV3, not anterior)
