TMJ Flashcards
TMJ is considered a modified hinge jt because a ________ separates the jt into ________ and _________ articulations with the ________________ and _______________ .
Disc
Upper and lower
Mandibular condyle and mandibular fossa of the temporal bone
The disc in the TMJ functions to:
Cousin the large repetitive force of mastication
The osteology of the TMJ consists of
Mandibular condyle
Mandibular fossa
Articular eminence of the temporal bone
TMJ joint classification:
Synovial
The articular eminence and mandibular condyle are both _________ resulting in an ________________
Convex
Incongruent jt
The articulating surfaces are covered in ____________ instead of hyaline cartilage because…..
Fibrocartilage
The jt must withstand repeated and high-level stress
The incongruency of the TMJ is addressed by a …
Biconcave disc!
Purpose of the articular disc in the TMJ
Allow for congruency through full ROM Increase stability Minimize loss of mobility Reduces friction Decrease biomechanical stress on TMJ
The inferior TMJ is a _______ jt that articulates…
Simple hinge
The mandibular condyle and inferior disc
The superior TMJ is a __________ jt that ariculates…
Gliding
The articular eminence and superior disc
The articular disc of the TMJ is attached to ________&_________ poles of condyle. This allows the condyle to…..
Medial and lateral
Rotate on the disc in an AP direction
The articular disc of the TMJ attaches to ________&____________. This will restrict posterior translation of the disc.
Joint capsule and lateral pterygoid anteriorly
The articular disc of the TMJ attaches to what posteriorly?
The bilaminar retrodiscal pad
The posterior attachment of the articulating disc of the TMJ has 2 parts. What are they and what do they do?
Superior lamina- assists the disc in translating anteriorly with mandibular depression
Inferior lamina- limits forward translation
The TMJ capsule is relatively ______ medial/laterally and is _______ & _______ anterior and posteriorly. What does this allow for
Firm
Thin & loose
Allows for anterior translation when mouth is open
The TMJ is predisposed to ____________________ due to lack of _________ of the anterior capsule and the _____________ of jt surfaces
Anterior dislocation of the mandibular condyle
Strength
Incongruence
Primary ligaments of the TMJ
Lateral (TM) ligament
Stylomandibular ligament
Sphenomandibular ligament
What ligament stabilizes the lateral potion of the capsule and helps guide movement of condyle during opening?
Lateral (TM) ligament
What TMJ ligament is weakest?
Stylomandibular ligament
What TMJ ligament is a swinging hinge that suspends the mandible?
Sphenomandibuliar ligament
What is the normal resting position of the TMJ and how is it maintained?
Lips closed, teeth several mm apart
Maintained by low activity of the temporalis muscle
List the Osteokinematics of the TMJ
Depression/elevation
Protrusion/retrusion
L&R lateral excursion (deviation)
Arthrokinematics of mandibular depression at the TMJ
Early phase- roll posterior (lower jt)
Late phase- glide anterior (upper jt)
Arthrokinematics of mandibular elevation at the TMJ
Early phase- glide posterior (upper jt)
Late phase- roll anterior (lower jt)
Arthrokinematics of mandibular protrusion at the TMJ
Anterior and slight inferior glide of condyle and disc
Arthrokinematics of mandibular retrusion at the TMJ
Posterior and slight superior glide of condyle and disc
Why is there no rotation (rolling) with protrusion and retrusion
Actions involve the upper jt only
Lateral excursion of the mandible at the TMJ involves primarily _________________________ of the condyle and disc within the fossa.
Side to side translation
During lateral excursion of the mandible the _________________ condyle serves as a relatively fixed pivot point
Ipsilateral
Arthrokinematics of lateral excursion (deviation)
Contralateral condyle glides anterior and to the side of deviation
Ipsilateral condyle spins
What works on the mandible to produce mandibular depression?
Gravity
Digastrics
Suprahyoids
Lateral pterygoid
What muscles act in the mandible to produce protrusion?
Masseters
Medial pterygoids
Lateral pterygoids
What muscles act in the mandible to produce retrusion?
Temporalis
Masseter
Digastric (assist)
What muscles work on the mandible to produce lateral deviation?
Contralateral med/lat pterygoid
Ipsilateral temporalis
Ipsilateral masseter
The _________ and ____________ form a functional sling around the angle of the mandible. Contracting both will create a powerful bite with a max force of _______.
Masseter and medial pterygoid
422 N or 95 lbs
Interaction with the Masseter and medial pterygoid can be effective at _______________________.
Grinding/crushing food
Shear force
Normal depression at the TMJ is ________, but only _______ is required for normal mastication.
35-50 mm
18 mm
The ability to fit 2 knuckles between your teeth is __________. 3 knuckle are ________.
Functional
Normal
Normal protrusion at TMJ is _______. A functional way to screen is to ___________________________.
3-6 mm
See if your lower teeth surpass your upper teeth
Normal retrusion at the TMJ is ________
3-4 mm
Normal lateral deviation at the TMJ is __________
10-15mm
S/Sx of temporomandibular dysfunction
Pain, popping, reduced bite force, reduced ROM wiyh mouth opening, headaches, tinnitus trigger points
Factors associated with TMD
Stress/emotional Daily oral parafunctional habits Asymmetric muscle activity Skeet bruxism Chronic forward head posture C-spine pathology
Describe Deviation of the mandible
Motion that produces an “s” curve with depression or protrusion
Describe deflections of the mandible
Motion that produces a “c” curve with depression or protrusion
Deviations and deflections at the TMJ may result from differently shaped __________________ or it may indicate ________________.
mandibular condyle heads
Pathology
Articular disc displacement occurs when?
The disc subluxes beyond articular eminence
Disc displacement with TMJ reduction results in a __________ when?
What is this called?
Clicking during mandibular depression and mandibular elevation
Reciprocal click
Disc displacement without reduction
Disc doesn’t relocate and patient will demonstrate limited mandibular motion due to mechanical obstruction (disc)
With disc displacement in the TMJ, the later the click occurs in the opening phase, the _____________ degree of dislocation
Greater
Patients coming in with TMJ complaints should also have their __________ and ____________ examined because ______________________ may affect tension in the ___________________ which can influence the function of the mandible
C-spine and upper quarter
Head and neck position
Cervical muscles
