TMJ Anatomy/Common Presentations Flashcards
Describe the structure of the disc of the TMJ:
biconcave fibrocollagenous structure between mandibular condyle and mandibular fossa of temporal bone
Anterior attachment of disc of TMJ:
Anteriorly attached to anterior capsule and lateral pterygoid
Posterior attachment of disc of TMJ:
Posteriorly attached to retrodiskal laminae - pulls disc back when lateral pterygoid muscle relaxes
Lower portion of joint capsule attaches what to what?
mandibular condyle to disc
Upper portion of joint capsule attaches what to what?
attaches disc to temporal bone
The TMJ is thin where?
posteriorly and anteriorly
The TMJ is thick where?
laterally and medially (collateral ligaments)
Describe movement in TMJ in first half of motion:
roll first half of motion in lower joint
Describe movement in TMJ in second half of motion:
glide in upper joint
Function of the TMJ disc:
- Separates joint cavity into two functional components
- Upper joint is a plane gliding joint for translation of mandible condyles
- Lower joint is a hinge joint that permits rotation of condyles - Force dispersion
What are the 2 layers of the retrodiscal laminae?
- Upper retrodiscal lamina
- Inferior layer curve behind the condyle & attach to capsule
Function of retrodiscal laminae?
- Stabilize the disk
- Prevents excessive translation of the disc over the condyle
- With anterior dislocation of the disc, the highly innervated laminae may be approximated between the mandibular condyle and mandibular fossa
Tempromandibular Ligament -
Function?
Counters what?
- Thickening of anterior joint capsule from neck of mandible to zygomatic arch
- Helps prevent posterior dislocation of the joint
- Prevents medial slippage of disc
- Counter lateral pterygoid pull
Temporalis:
Origin -
Insertion -
Action -
- Origin: temporal fossa
- Insertion: coronoid process on anterior ramus of mandible
- Action: elevate mandible (mouth closing)
Masseter:
Origin -
Insertion -
Action -
- Origin: Inferior and medial zygomatic arch
- Insertion: coronoid process of lateral ramus of mandible
- Action: elevation and protrusion of mandible
Medial Pterygoid:
Origin -
Insertion -
Action -
- Origin: medial surface of lateral pterygoid plate, pyrymidal process of palatine bone, tuberocity of maxilla
- Insertion: medial aspect of mandibular ramus
- Action: elevate and protrude mandible
Lateral Pterygoid:
Origin -
Insertion -
Action -
- Origin: superior head to lateral surface of greater wing of sphenoid bone, inferior head to lateral surface of lateral plate
- Insertion: neck of mandible, articular disc, TMJ capsule
- Action: protrude and depress mandible (open), lateral deviation of mandible (unilaterally)
Infrahyoid muscles:
Innervation -
Action -
Innervation - C1-C3
Action - Depress hyoid
Suprahyoid muscles action -
Elevates hyoid
Digastric action -
depresses mandible against resistance and elevates hyoid
Mandibular nerve:
Sensory -
Motor -
- Branch of trigeminal
- Sensory: teeth, temporal region, external auditory meatus, tympanic membrane, lower lip, lower face, mucosa anterior 2/3rds of the tongue, floor of oral cavity
- Motor: muscles of mastication
T/F During first 50% of motion of TMJ opening the disc remains stationary.
True
What occurs to disc during last 50% of TMJ opening?
- Disc pulled anteriomedially by lateral pterygoid
- Disc slides along with condyle
Normal opening of TMJ -
35-50 mm
Normal lateral deviation of TMJ -
10-15 mm
Normal protrusion of TMJ -
3-6 mm
Normal retrusion of TMJ -
3-4 mm
Open pack position for TMJ -
Slight opening (tongue resting on roof of mouth)
T/F 65% - 85% of the U.S. population experience some TMD symptoms during their lives.
True
T/F An estimated 5% - 12% of the population has progressed from acute to chronic TMD symptoms
True
Chronic TMD is more commonly seen in what sex?
Women: 8-15%
Men: 3-10%
TMD Group 1: Masticatory Muscle Disorders -
Myofacial:
- With normal opening
- With limited opening
TMD Group 2: Disc Displacements -
Disc displacement:
- With reduction
- W/o reduction with limited opening
- W/o reduction w/o limited opening
TMD Group 3: Joint dysfunction -
Degenerative/Inflammatory:
- Arthralgia
- Osteoarthritis
- Osteoarthrosis
What 3 mechanisms of masticatory muscle disorders?
- Strain (acute)
- Direct trauma (blow to the face, excessive widening with dental procedure, etc.) - Overuse injury: (chronic with insidious nature)
- Parafunctions (grinding, nail biting, etc.)
- Guarding - Centrally mediated pain
T/F Masticatory Muscle Disorders can result in trigger points with pain referral to face, teeth, auricular area, temporal area, periocular area, & upper cervical area.
True
Physical examination for Masticatory Muscle Disorders:
- Tenderness & increased turgor of muscles of mastication
- Aberrant (less coordinated) motion pattern with AROM testing
- Limited ROM when stretching involved structure (or normal motion)
- Painful at end-range motion - Pain with resistance testing to involved structure
- Pain with tongue depressor biting on ipsilateral side
Joint dysfunctions of the TMJ involve what structures?
Involve the disc, joint surfaces, capsule, ligaments, retrodiscal tissue, and/or synovium.
Examples of mechanisms that can cause Joint dysfunction of TMJ:
- Macrotrauma
- Microtrauma
E.g. repetitive loading with condyle sliding over disc, repetitive compression/ tensile loading of retrodiscal tissue
Disc Displacements & Joint Dysfunctions general findings (pain where/when?)
- Preauricular pain (pain in and around ear) commonly primary complaint
- Painful palpation of joint line
- Pain with tests that place compressive load on joint structures
DDWR -
- Audible clicking and/ or palpable clicking (1/3 trials)
- Joint motion typically intact
DDWOR -
- (without reduction – remains anteriorly displaced)
- Report of catching sensation with opening/ closing
- Limitations in opening ROM: prevents anterior translation of condyle
C-type curve -
- Anterior displacement of a disc (ipsilaterally) without reduction or unilateral muscle hypomobility
- Hypomobility of ipsilateral joint
- Rolling during first half but no anterior sliding due to disk blocking
S-type curve -
- Muscular imbalance or medial displacement
- Condyle “walks around the disc”
Early deviation of the TMJ can mean what?
Spasm
Late deviation of the TMJ can mean what?
capsulitis/ tight capsule
What is the clicking during TMJ opening?
- Partial anterior displacement or dislocation of the disc in resting position
- Opening click indicating reduction of the disc as the mandibular condyle passes over the posterior border
Reciprocal clicking -
- Clicking occurs with closing
- Condyle slips posteriorly over (anteriorly) displaced disc
With DDWOR, will expect compression loading where?
Retrodiscal lamina
Open lock pathomechanics -
- Condyle moves over the anterior rim of the disc at max opening
- The disc lies posterior to the condyle outside of the fossa, preventing the condyle from sliding back (mouth stuck open)
During open lock, will see guarding in what muscles?
Masseter and temporalis guard
Need what for relocation of disc in open lock TMJ?
Distraction for relocation necessary
Closed lock pathomechanics -
- Disc displacement without reduction
- Partial anterior displacement or dislocation of the disc in resting position
- Mandibular condyle unable to pass over the posterior border of the disc with opening (disc remains bunched anterior to the mandibular condyle)
Category 3: Joint dysfunctions include what?
- Degeneration
- Osteoarthritis
- Osteoarthrosis
- Acute on chronic
Category 3 Joint dysfunctions: Degeneration
excessive loading, prolonged chemical irritation
Category 3 Joint dysfunctions: Osteoarthritis
active inflammatory process (acute)
Category 3 Joint dysfunctions: Osteoarthrosis
no active inflammatory process (chronic with failed healing response)
Category 3 Joint dysfunctions: Acute on chronic
osteoarthrosis with acute irritation -> acute inflammatory response
Clinical manifestations of category 3 joint dysfunctions:
- May report crepitus (clicking/popping)
- Unilateral vs. bilateral
- Deviation with opening, protrusion, contralateral deviation (unilateral)
