5 TMJ Flashcards
arcs of opening
1st arc: rotation
2nd arc: translation
ginglymoid and arthodial joint
ginglymoid = rotation/hinging arthodial = translation, gliding
mandibular condyle dimensions
greater mediolateral dimension than anteroposterior
mandibular condyle poles
medial pole is More prominent
lateral pole is Less prominent
intersect at anterior portion of f. magnum
extend medially and posteriorly
mandibular condyle articular surface
posterior surface has larger articular surface
articular (glenoid) fossa and eminence
of zygomatic arch of temporal bone
eminence = functioning
fossa = nonfunctioning, ant. to dividing petrytympanic fissure
mandibular fossa = large depression behind articular fossa
innervation
trigeminal CN V mandibular branch (III)
masseteric, Auriculotemporal, deep temporal
irrigation of TMJ
superficial temporal a.
internal maxillary a.
middle meningeal a.
colateral/discal ligament attachments
two short ligaments: medial/distal pole –> disc
colateral/discal ligament functions
maintain disc and mandibular condyle
prevent excessive rotation
capsular ligament/fibrous capsule attachments
superiorly to temporal bone around border of articular surfaces of mandibular fossa and articular eminence –> inferiorly to neck on condyle
capsular ligament/fibrous capsule functions
surrounds TMJ
keeps articular surfaces in contact
temporal and mandibular fossa remain in contact
produce synovial fluid
lateral ligament OOP attachments
outer oblique portion
lateral surfaces of zygomatic arch and articular eminence –> posterior surface of condyle neck
lateral ligament OOP functions
prevents excessive rotation in 1st arc of opening
lateral ligament IHP attachments
inner horizontal portion
outer surface of zygomatic arch and articular eminence –> lateral surface of disc or lateral pole
lateral ligament IHP functions
prevents posterior movement (of condyle into mandibular fossa)
assists/prevents straining of lateral pterygoid m.
sphenomandibular ligament attachments
sphenoidal/angular spine (sphenoid) –> lingula
sphenomandibular ligament functions
prevents excessive opening (a little)
stylomandibular ligament attachments
styloid process (temporal) –> posterior border of mandible
stylomandibular ligament functions
oblique orientation: prevents excessive protrusion
masseter function
elevate mandible, close teeth together
masseter origin
zygomatic arch (inferior and medial)
masseter insertion
lateral surface of rami and angle of mandible
masseter fibers
deep vertical and superficial oblique
two movements: elevation and protrusion
temporalis function
elevate (teeth contact) and retrude mandible
temporalis origin
temporal fossa on cranium
temporalis insertion
coronoid process, anterior border of ramus, temporal crest
temporalis fibers
anterior (vertical) E
middle (oblique) E & R
posterior (horizontal) R
medial pterygoid function
elevate (teeth contact)
medial counterpart to masseter
medial pterygoid origin
pterygoid fossa (sphenoid)
medial ptergyoid insertion
medial angle of mandible
lateral pterygoid function
one: move mandible laterally
both: depress, protrude
lateral ptergyoid origin
lateral pterygoid plate (sphenoid) and greater wing
lateral pterygoid insertion
pterygoid fovea (condylar process)
anterior part of articular disc
capsular ligament
digastric posterior O –> I
mastoid notch –> hyoid
digastric anterior O –> I
medial and inferior surface of mandible close to midline –> hyoid
suprahyoids
genioyhoids, mylohyoids, digastric
suprahyoid functions
depress
digastric function
holds mandible in place, hyoid elevates to assist in swallowing
infrahyoids
omohyoid, sternohyoid
infrahyoid functions
hold hyoid in place
all hyoid mm.
open mouth, depress mandible
elevation mm (3)
masseter
temporalis (ant vert and mid oblique)
medial pterygoids
depression mm (2)
both lateral pterygoids
supra and infrahyoids together
retrusion (2)
temporalis (post horiz)
suprahyoids (w/ help from infras)
protrusion (2)
bother lateral pterygoids
masster
medial ptergyoid
lateral excursion
right lateral ptergyoid moves mandible left
biomechanics: 3 orthopedic principles
- Ligaments do not participate actively in function of TMJ. They restrict/permit movements.
- Ligaments do not stretch, they elongate if traction force is applied, causing normal joint function to be compromised.
- The articular surfaces of TMJ must maintain contact (achieved by elevator muscles, capsular ligament).
