TMJ Flashcards
Dental Occlusion
How teeth fit together
Describe the diarticular synovial TMJ
Upper joint: Between articular eminence and disk
Lower joint: Between condyle and disk
Disk is attached to and travels with condyle
*Disk is thicker in the back
Articular capsule of TMJ
Lax anteriorly and posteriorly
Reinforced laterally
Inferiorly contributes to collateral ligaments
Collateral ligaments of TMJ
Reinforcement of inferior capsule
Hold disk to condyle
Must be torn for displacement of disk
Lateral ligaments of TMJ
Run at various angles, from zygomatic process to condyle
Lateral Tempro-mandibular ligament: Inner horizontal and outer oblique fibers
Primary reinforcing ligament
Stabilizes lateral joint
Accessory ligaments of TMJ
Sphenomandibular and Stylomandibular
- Minor suspensory role
Mandibular-Malleolar
- Tinitis?
Movement of the condyles during (R) lateral excursion
R condyle spins
L condyle drops and translates
TMJ Depression
Early phase (1/3): Lower joint rolling Late phase (2/3): Upper joint gliding forward (along with disk)
Lateral Pterygoid function
Assists anterior glide of disk
Disk Displacement with reduction (DDWR)
Patient symptoms:
- Joint noise during mandibular opening and closing
- Two “pops” or “clicks” (one on opening, one on closing)
Disk in out of place when mouth is closed, slips into place upon full opening
Disk Displacement without reduction (DDWoR)
Acute
-Depression: Opening limited to ~20 mm, deflection toward ipsilateral side
- Protrusion: Limited, deflection toward ipsilateral side
May feel just one pop
Disk doesn’t pop into place when mouth opens – it restricts the opening
Temporalis
From temporal fossa to coranoid process
Elevation, Retrusion, Ipsilateral excursion of mandible
Refers pain to teeth
Masseter
Superficial and deep components from zygomatic arch to ramus of mandible
- Adhesions can form between superficial and deep
Elevation, Retrusion, Ipsilateral excursion of mandible (powerful)
Medial/Internal Pterygoid
From pterygoid plate of sphenoid to medial ramus of mandible
Elevation, Protrusion, Contralateral Excursion of mandible
Forms a sling with masseter for powerful elevation
Lateral/External Pterygoid
Two heads from pterygoid plate of sphenoid to neck of mandible, articular disk, and capsule of TMJ
Protrusion, Contralateral Excursion of Mandibler
-Pierces the medial pterygoid
Supra-hyoid Muscles - Depressors
Digastric, stylohyoid, geniohyoid, mylohyoid
Digastric
From mastoid and lower mandible to hyoid (through sling on hyoid)
Primary depressor and retrusion
Stylohyoid
From styloid process to hyoid
Depression of mandible
Geniohyoid
From symphysis of mandible to hyoid
Depression of mandible
Mylohyoid
From floor of mandible to hyoid
Depression of mandible
Infrahyoid Muscles
Sternohyoid, thyrohyoid, omohyoid
Stabilize hyoid to facilitate manidbular depression
Maximal Rest Position
Desirable position of mandiblewith minimal tonus of jaw musculature and no occlusion of teeth
Freeway Space (Interocclusal Clearance)
Space between teeth at rest
Postural Position
Rest position of the tongue
Anterior-superior tip of tongue on hard palate behind incisors
TMJ relation with FHP
Infrahyoid muscles stretched
Mandible retruded and depressed
Suprahyoid shortened
