TMJ Anatomy and Clinical Presentation Flashcards
the joint capsule of the TMJ is divided into ____ portions. Describe each
two portion
upper → attaches disc to temporal bone
lower → attaches mandibular condyle to disc
the joint capsule itself is thin A/P and thickened/supported M/L by collateral ligaments
describe the structure and function of the disc at the TMJ
bi-concave and flexible
oval fibrocartilage plate
made up of A/P and intermediate bands
function is to separate joint cavity into 2 functional components and disperse force
where is the disc located in the TMJ?
positioned between the mandibular fossa of the temporal bone and condylar process of the mandible
describe the attachments of the disc in the TMJ
posterior attachment → retrodiscal lamina
anterior attachment → lateral Pterygoid (pulls disc forward during mouth closure) and anterior articular capsule
describe the structure of the retrodiscal lamina
ligament from temporal bone to the posterior border of the disc
made up of 2 layers divided by a loose connective tissue
has elastic fibers that aid in disc recoil during mouth closing
what is the function of the retrodiscal laminae?
- stabilize the disc
- prevent excessive translation of the disc over the condyle
describe the structure and function of the temporamandibular ligament
- Structure → fan shaped, thickening of anterior joint capsule from neck of mandible to zygomatic arc
- Function
- helps prevent posterior dislocation of the joint
- prevents medial slippage of disc
- counters lateral pterygoidpull
List the muscles of mastication
- Temporalis
- Masseter
- M/L Pterygoid
List the origin, insertion and action of the Temporalis
- Origin → temporal fossa
- Insertion → coronoid process on anterior ramus of mandible
- Action → elevate mandible
List the origin, insertion and action of the Masseter
- Origin → inferior and medial zygomatic arch
- Insertion → coronoid process of lateral ramus of mandible
- Action → elevation and protrusion of mandible
List the origin, insertion and action of the medial pterygoid
- Origin
- medial surface of lateral pterygoid plate
- pyramidal process of palatine bone
- tuberosity of maxilla
- Insertion → medial aspect of mandibular ramus
- Action → elevation and protrusion of mandible
List the origin, insertion and action of the lateral pterygoid
- Origin
- superior head to lateral surface of greater wing of sphenoid
- inferior head to lateral surface of lateral plate
- Insertion → neck of mandible and articular disc as well as TMJ capsule
- Action
- protrude and depress mandible
- lateral deviation of mandible (unilaterally)
What innervates the infrahyoids and what is their gross action?
branches of C1-C3
depress hyoid
what is the role of the Digastric?
depress mandible against resistance and elevates hyoid
what innervates the muscles of mastication?
Mandibular nerve (V3 → branch of trigeminal)
The Mandibular nerve provides sensory info for what areas?
- Teeth
- Temporal region
- external auditory meatus
- tympanic membrane
- lower face and lip
- mucosa anterior 2/3rds of the tongue
- floor of oral cavity
Desribe the arthrokinematics of the TMJ joints
- 50% of motion occurs as rolling in the lower joint
- condyle on temporal bone
- disc remains stationary
- 50% of motion occurs in upper joint as gliding
- begins at mid-opening
- disc pulled anteriomedially by lateral pterygoid
- condyle along sigmoid-shaped temporal bone
- disc slides along w/condyle
List the osteokinematic motions and their normative values for the TMJ
- Opening → 35-50 mm
- Lateral deviation → 10-15 mm
- Protrusion → 3-6 mm
- Retrusion → 3-4 mm
what is the resting (open pack) position for the TMJ?
slight opening (tongue resting on roof of mouth)
how common is TMD?
65-85% of US population experience some TMD symptoms during their lives
more common in women (8-15%) than men (3-10%)
Your differential list for someone who presents with TMJ issues includes what broad categories?
- Musculoskeletal
- Myofacial
- Internal derangement
- degenerative arthropathy
- Intra-oral → refer to dentist
- C-Spine referral
- Neurogenic
- Peripheral neuralgia (trigeminal normally)
- Vascular
- cardiac referral (angina, MI)
- HA
- Other
TMD can be broken down into what 3 broad categories and subcategories?
- Masticatory Muscle disorders
- with normal opening
- with limited opening
- Disc displacements
- with reduction
- without reduction and with limited opening
- without reduction and without limited opening
- Joint Dysfunction
- arthralgia
- osteoarthritis
- osteoarthrosis
Masticatory Muscle Disorders can be caused by what?
- Acute → strain
- direct trauma (blow to the face, excessive widening with dental procedure, etc.)
- Chronic → overuse injury
- parafunctions
- guarding
- Centrally mediated pain
define parafunctions
clenching, grinding teeth, nail biting, etc
behaviors relating the jaw movements that are not normal
what can result from masticatory muscle disorders?
- reduced motion and altering of occulsion
- trigger points with pain referral to:
- face
- teeth
- auricular area
- temporal area
- perioccular area
- upper cervical area
List some physical exam findings for an individual with masticatory muscle disorders
- tenderness and increased turgor of muscles of mastication
- aberrant motion pattern with AROM testing
- Limited ROM when stretching involved structure
- painful at end-range motion
- pain w/resistance testing to invovled structure
- pain w/tongue depressor biting on ipsilateral side
describe the TMD category of joint dysfunction
invovles the disc, joint surfaces, capsule, ligaments retrodiscal tissue, and/or synovium
Mechanisms involve micro/macrotrauma
can lead to guarding
List the general findings for Disc displacements and Joint Dysfunction
- Perauricular pain commonly primary complaint
- painful palpation of joint line
- pain with tests that place compressive load on joint structures
list clinical findings for DDWR
- audible clicking and/or palpable clicking (1/3 trials)
- joint motion typically intact
list clinical findings for DDWOR
- report of catching sensation with opening/closing
- limitations in opening ROM
describe the pathomechanics of an C-type curve
anterior displacement of disc (ipsilaterally) without reduction or unilateral muscle hypomobility
hypomobility of ipsilateral joint
describe the pathomechanics of an S-type curve
muscular imbalance or medial displacement
condyle “walks around the disc”
describe what is going on during DDWR
- Clicking:
- 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
describe what is occuring during DDWOR
the disc no longer reduces, but remains anteriorly reduced
this can limit mouth opening
result in compression loading on retrodiscal lamina
Describe what occurs with Open Lock
the condyle moves over the anterior rim of the disc at max opening
the disc lies posterior to the condyle outside of the fossa which prevents the condyle from sliding back
masseter and temporalis guard
Describe what occurs with closed lock
disc displacement w/o 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)
what is Joint dysfunction? What are the types that can occur at the TMJ?
inflammation of capsule, ligaments, retrodiscal tissue, synovium of the TMJ
structural changes of joint surfaces, 3 types:
Degenerative, Osteoarthritis, Osteoarthrosis
Describe the clinical presentation for joint dysfunction of the TMJ
- May report crepitus
- unilateral vs bilateral
- deviation with opening, protrusion, contralateral deviation (unilateral)
