TMJ Flashcards
what is the TMJ?
- temporomandibular joint
- joint on each side of the head that allows for movement of the mandible for speech and mastication
what are disease/disorders of the TMJ called?
- TMD
what bones are involved in the TMJ?
- the 2 temporal bones and the 2 condyles of the mandible
what is fibrocartilage?
- surfaces of the TMJ are covered in strong and durable cartilage called fibrocartilage
where does the condyle fit into on the temporal bone?
- the articular fossa or the glenoid fossa
what is a fibrous joint capsule?
- completely encloses the TMJ
- membranes inside the capsule secrete synovial fluid to help lubricate the joint
- 2 portions of the joint capsule
what are the 2 portions of the joint capsule?
- superior: wraps around articular eminence and articular fossa
- inferior: wraps around mandibular condyle
what is the disc of the joint?
- the fibrous disc of the joint is located between the temporal bone and the condyle of the mandible
- shape conforms with the shape of the adjacent bones (cap shape)
2 compartments of the disc of the joint
- upper synovial cavity
- lower synovial cavity
where does the disc attach to?
- the lateral and medial poles of the mandibular condyle but not to temporal bone (only indirectly through the capsule)
how does the joint stay lubricated?
- membranes inside the capsule secrete synovial fluid to help lubricate the joint
how is the mandible joined to the cranium?
- through ligaments, which is a band of fibrous tissue that connects bones
3 pairs of ligaments connecting the mandible to the cranium
1 - TMJ ligament
2 - sphenomandibular ligament
3 - stylomandibular ligament
where are the TMJ ligaments located?
- on the lateral side of each joint reinforcing lateral side of joint capsule
- goes from zygomatic process to neck of condyle
- prevents excessive retraction of the mandible
- provides strength to the joint
where are the sphenomandibular ligaments located?
- spine of the sphenoid bone to lingula of mandibular foramen
- limits protrusion
- this ligament is a landmark for the administration of inferior alveolar local anesthetic block
where are the stylomandibular ligaments located?
- styloid process to angle of mandible
- also limits protrusion
what do gliding movements allow the jaw to do?
occurs mainly between disc and articular eminence in the upper synovial cavity. condyle moves down and up the articular eminence
allows the mandible to go forward and backwards
- protrusion: bilateral contraction of lateral pterygoid muscles
- retraction: temporalis
what do rotational (hinging) movements allow the jaw to do?
occurs between disc and condyle in the lower synovial cavity. condyle rotates up and down
- depression: anterior suprahyoid muscles; lateral pterygoid
- elevation: masseter; medial pterygoid; temporalis
opening and closing the jaw
- requires gliding and rotation of the TMJ
- open: protrude and depress
- close: retract and elevate
what is the power stroke and how does it occur?
- when teeth crunch the food
- moving from laterally deviated to midline
what occurs when there is food on the right side of the mouth?
- the mandible will be deviated to the right by the lateral pterygoid muscle
- then, the mandible will return to center involving a retraction of the left side (temporalis)
- at the same time, all the closing muscles on the right contract to crush the food (masseter, medial pterygoid, temporalis)
what is lateral deviation?
- shifting to one side
- must happen to chew food
- lateral deviation back to midline
resting position of the TMJ
- no teeth contact
- muscular balance
- space of 2-4 mm between teeth (freeway space)
- with reduced vertical dimension (teeth loss) = overclosed = muscular imbalance
- with increased vertical dimension (mouthbreathing/open mouth) - muscular imbalance
what is TMD? what are some symptoms?
- temporomandibular disorder
- tenderness, swelling, pain, muscle spasm. limited or deviated jaw opening
- important to recognize
- record habits; palpate, note deviations, clicking; symptomatic vs asymptomatic
