Foundation Structures Flashcards
3 planes of mand motion
Midsagittal- down midline
Transverse- horizontal, top to bottom
Coronal- frontal, front and back
TMJ moves in the
Transverse, horizontal plane
TMJ
Area where mand condyle articulates at the base of cranium w temporal bone squamous portion
Bones of skull
Temporal (zygomatic process)
Sphenoid
Zygomatic (cheek bone)
Mandible (condyle and coronoid processes)
What muscle inserts on the coronoid process? Condylar process?
Coronoid- temporalis
Condylar- lateral pterygoid
What forms the inferior part of the TMJ
Condylar process of the mandible
What does the rod through the typodont represent?
The transverse axis that the mandible rotates around
What forms the upper portion of the TMJ
Mandibular fossa of the temporal bone
Articulate eminence
Convex Area directly anterior to the mand fossa of the temporal bone
STF
Squamo- tympanic fissure
Posterior roof of mandibular fossa
Sphenoid bone
Middle portion of cranial base
Pterygoid process
Why is pterygoid process important
Of sphenoid bone
Important because it is the origin for 3 mastication muscles
Zygomatic bone
Cheek bone
Second most commonly fractured bone of face
Masseter origin
Where does the masseter originate
Zygomatic bone
What makes up the TMJ
Mandibular fossa of temporal bone
Articulate disc- dense fibrous CT
Condylar process of mandible
What moves with the head of the condyle
The articulate disc
Functions of the articular disc of TMJ
Splits TMJ into functional compartments
Upper= translation
Lower= rotation
Stabilizes condyle, Helps lubricate TMJ
Absorbs shock
Reduces physical wear/strain
Regulates movement
Functional compartments of TMJ
Upper= translation
Lower= rotation
Split by the articular disc
TMJ fibrous capsule
Tube of tissues that encloses TMJ
Inner layer secretes synovial fluid
Outer layer is thick tissue that protects and limits movement
4 muscles of mastication
Masseter
Temporalis
Medial pterygoid
Lateral pterygoid
Masseter
O= zygomatic arch I= lateral angle of mandible
Function- elevates mandible
Temporalis
O= temporal fossa I= coronoid process of mandible and anterior Ramos
Function- anterior elevates mandible, posterior retrudes the mandible
Medial pterygoid
O= medial surface of lateral pterygoid plate of sphenoid I= medial angle of mandible
Function- elevates mandible
Lateral pterygoid upper vs lower
Upper
O= great wing of sphenoid bone
I= articular disc and condyle
Function= opens mandible, pulls articular disc forward
Lower
O= lateral pterygoid plate of sphenoid
I= neck of condyle
Function- symmetrical= opening and protrusion
Asymmetrical= lateral movement of mandible
Articular disc attachments
Posterior- retrodiscal tissue (bilaminar zone), loose ct that is highly innervated/vascular that attaches disc to tympanic plate and capsule
Anterior- lateral pterygoid
Medial- condyle and capsule
What is the position of the articular disc determined by
Elastic fibers of the retrodiscal tissue bulling back
Vs
Lateral pterygoid pulling forward
A contraction of the right lateral pterygoid results is what movement of the mandible
A left movement
Mandible movement in each plane
Sagittal- symmetrical movement of mandible, muscles on both sides are working, opening and closing
Transverse- rotation
terminal hinge movement is when mouth is all the way open without mand moving forward, 25 mm
Translation- disc moves anteriorly to protrude mandible, about 10mm
Complex movement- movement of the mandible that combine rotation and translation
Posselts diagram
Extreme mand motion record
Recorded in three planes and 3 points
Aka incisor, molar, and condylar
Retruded contact
RC
Superior limit of terminal hinge movement
Aka centric relation or centric occlusion
Stages of opening
- Pure rotational opening - rotational movement with condyles in terminal hinge position, without translation
- Rotation and translation- condyle is positioned down articular eminence, slightly protrudes
- Yawning- Extent of opening is limited by sphenomandibular ligament
Anterior guidance
Occurs during protrusion when mandible moves and causes mand teeth to glide along lingual of max teeth, disoccluding posterior teeth
Protrusive interference
Premature contact from MI to protrusive
Between mesial aspects of mand teeth and distal aspects of max teeth
No slip from MI to RC?
Condyles are naturally in centric relation
Optimal condylar position
When MI = RC
