TMD- Anatomy + Biomechanics Flashcards
(23 cards)
What % of ppl with TMD require tx
3.6-7% of indvs
What % of TMD is due to internal derangemnt and muscular disorder
int derangment- 26-51%
Muscular disorder- 30-33%
What type of jt is the TMJ
ginglymaorthroidal (hindge + gliding)
What is the ant and post wall of mandibular fossa
ant- articular eminence of squamous temporal bone
post- Tympanic plate
What is the load bearing portion of the TMJ + where will most degerneration occur
the articular eminance (articular surface)
–mandibular condyle and lower jt space.
What does the articular disk split and what mm attaches to it
Firm, oval fibrous plate bw condyle and articular fossa–splits it into upper (discotemporal) and lower compartments (discomendibular)
Sup head of lat pterygoid
What is found posterior to disk and feature of it
bilaminar zone (retrodiscal)- very well innervated and vascularized. - causes pain/problematic
What allows rotational movement at the tmj
Medial and lateral attachments to the condyles through collateral ligaments allow rotational movement of the disc on the condyle during opening and closing.
What does the articular capsul form and where is it thickest and what does it limit
Froms tempomandibular lig
-Thick anterolat and lat (thin anteromed, med + post)
-limits movement of the mandible
What are the 2 accessory ligs of the mandible and what is there function
- sphenomandibular- no influence on madibular mvmt (protects blood vessels and nerves)
- Stylomandibular lig- limits end ranges of protrusion
What are the 2 main movement of the TMJ
Rotary/hinge- axis around centers of condyle
Translatory- mvmt of mandible in the AP/ML directions
what compartment does rotation and translation typically occur
- Rotation is primarily between the disc and condyle in the LOWER compartment. (1st step)
- Translation is primarily between the articular eminence and disc (and mandible) in the UPPER compartment.
What is the primary and secondary movers in depression of mandible
Prime- gravity
Secondary- Supra/infrahyoid mm, lat pterygoid, digastric, geniohyoid, mylohyoid
What mm are used in elevation of the mandible (3)
Tempralis
Masseter
Medial pterygoid
how wide should u be able to open your mouth and how much do u need for ADLs
3 fingers (40-60mm)
need 25-35mm for adls
What is the typical opening sequence of the TMJ
condyles rest on disk
as madible moves ant with opening the disc moves med and post untill collateral ligs and lat pterygoid stop its mvmt (disc is not seated)
if there is a c curve while opening what does it indicate
Hypomobility to towards side of deviation (displaced disc without reduction/unilat hypomobility)
if there is a s curve while opening what may it be due to
- mm imbalance/ spasm
- late deviation due to capsulitis
What should be the primmary mm in protrusion and what measurement should it be over
Protrusion primarily by LP and should be over 7mm
What should be the normal amount of retrusion
1-2mm
if laterally moveing to the right what side would be the working and balancing side
R- Working side (but esentially resting/not moveing)
L- balancing side (but moving inf + medially)
On what side of the jt does DJD and disc perforations typically occur
along lat aspects of the TMJ
With unilateral tmj pain what side should u chew on
On same side as pain (as Working Side actually has less mvmt than balancing side)
