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Biomechanics Winter 2024 > TMJ & Ventilation > Flashcards

TMJ & Ventilation Flashcards

1
Q

List all the structures that attach to the TMJ disc

A

Posterior:
- inferior/superior retrodiscal lamina

Anterior:
- mandible + capsule
- superior head of lateral pterygoid
- temporal bone

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2
Q

Name the ligaments of the TMJ and their respective jobs

A

Primary:
- lateral ligament (horizontal & oblique fibers)
- stabilizes lateral aspect of capsule

Accessory:
- stylomandibular
- sphenomandibular
- helps suspend mandible from cranium

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3
Q

What are the osteokinematics, arthrokinematics and muscles of protrusion?

A

Osteo:
- anterior translation

Arthro:
- anterior slide, no rotation

Muscles:
- Masseter (bilateral)
- medial pterygoid (bilateral)
- lateral pterygoid (bilateral)

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4
Q

What are the osteokinematics, arthrokinematics and muscles of retrusion?

A

Osteo:
- posterior translation

Arthro:
- posterior slide

Muscles:
- oblique/posterior fibers of temporalis

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5
Q

What are the osteokinematics, arthrokinematics and muscles of lateral excursion?

A

Osteo:
- side-to-side translation (slight horizontal plane rotation)

Arthro:
- contralateral anterior slide of one condyle; ipsilateral condyle acts as pivot

Muscles:
- masseter (unilateral ipsilateral excursion)
- temporalis (unilateral ipsilateral excursion)
- medial pterygoid (unilateral contralateral excursion)
- lateral pterygoid (unilateral contralateral excursion)

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6
Q

What are the osteokinematics, arthrokinematics and muscles of depression?

A

Osteo:
- translates anterior and downward

Arthro:
Early Phase
- rotation (condyles roll posteriorly)

Late phase:
- slides anterior & inferior
- disc moves anterior
- limited by superior retrodiscal lamina

Muscles:
- suprahyoids (if stabilized by infrahyoids)
- inferior head of lateral pterygoid

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7
Q

What are the osteokinematics, arthrokinematics and muscles of elevation

A

Osteo:
- translates posterior and superior

Arthro:
Early phase
- initiated disc movement by superior retrodiscal lamina
- slides posterior & superior

Late phase
- rotation (condyles roll anterior)

Muscles:
- masseter (bilateral)
- Temporalis (bilateral)
- medial pterygoid (bilateral)

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8
Q

During elevation of the mandible what does the superior retrodiscal lamina do?

A
  • initiates the start of pulling the disc back into the mandibular fossa
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9
Q

During elevation of the mandible what does the superior head of the lateral pterygoid do?

A
  • acts eccentrically to slowing control the disc back into the mandibular fossa
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10
Q

How does the lateral pterygoid adjust to different bite resistances?

A

Low-resistance:
- intermediate disc region positioned between condyle and articular eminence

High-resistance:
- momentary reduction in joint pressure (contralateral side)
- superior head of lateral pterygoid pulls disc forward
- thicker, posterior disc between condyle and articular eminence

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11
Q

Walk through the steps of what happens to the TMJ disc during a full cycle of opening and closing

A

Opening:
- disc is still until later stage of opening when disc is pulled anteriorly by superior head of lateral pterygoid
- fully open, the disc sits between the articular eminence and mandibular condyle

Closing:
- superior head of lateral pterygoid acts eccentrically to slowly return disc back into the mandibular fossa

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12
Q

How does capsular fibrosis of the TMJ develop?

A

unresolved/chronic inflammation of fibrous capsule
- leads to overproduction of fibrous connective tissue = capsular fibrosis

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13
Q

Describe the sequence of events involved with TMJ internal disc derangement

A

Reduction:
- at rest, disc is anterior to mandibular condyle (condyle touching retrodisctal tissue, NOT disc)
- depression occurs, moves past inferior posterior disc & clicks onto disc for normal relationship (contact remains normal throughout depression)
- with elevation, condyle translates posteriorly and slips out from under the disc again (second click)

Without reduction:
- retrodiscal structures/ligaments are too lax to reduce disc to normal position
- results in block from fully opening mouth

later the click the more severe

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14
Q

What is Temporomandibular disorder (TMD)?

A

broad fake term to cover a multitude of issues associated with TMJ

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15
Q

Explain how a forward head posture affects the TMJ

A
  • stretches the infrahyoid muscles
  • pulls hyoid inferior and posterior (this tension is transferred to mandible via suprahyoids
  • mandible is then pulled into retrusion & depression
  • omohyoid places more pull on mandible via scapular attachment
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16
Q

What is the result of the effects of a forward head posture on the TMJ

A
  • posterior displacement of condyles compresses retrodiscal tissues = inflammation
  • lateral pterygoid pulls mandible into protrusion to avoid inflammation = spasms
  • causes internal derangement of disc
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17
Q

How could you help a patient with chronic forward head posture?

A
  • manual therapy if hypomobility is present
  • strengthening to deep neck flexors and mid-lower traps
18
Q

What are some symptoms of internal derangement of the disc?

A
  • pain
  • popping/clicking
  • labored/reduced jaw movement
19
Q

What is the difference between quiet and force expiration?

A

Quiet:
- sedentary, at rest, low metabolic demands

Forced:
- strenuous activities, rapid exchange of air

20
Q

What is total lung capacity?

A
  • total amount of air your lungs can hold
  • about 5.5-6.0L
21
Q

What is vital capacity?

A
  • max volume exhaled after max inhalation
22
Q

What is tidal volume?

A
  • air moved in/out of lungs during each ventilation cycle
  • at rest is about .5L
23
Q

What is Boyle’s law?

A
  • volume is inversely proportional to pressure
  • EX: increase in volume = decrease in pressure
24
Q

How is quiet inspiration achieved?

A
  • diaphragm
  • scalenes
  • external intercostals
25
Q

Explain the difference between muscles of inspiration vs expiration

A

Muscles of inspiration:
- increase intrathoracic volume

Muscles of expiration:
- decrease intrathoracic volume

26
Q

Why is it harder to breathe in rather than breathing out?

A
  • inspiratory muscles have to overcome the elastic recoil of the lungs and connective tissues
  • quiet expiration is passive so it is easier for the body to release the air rather than pull it in
27
Q

How does quiet expiration occur?

A
  • passively from the elastic coil of lungs, thorax, and relaxing diaphragm
28
Q

How does forced inspiration occur?

A
  • diaphragm
  • external intercostals (dorsal/upper regions)
  • serratus posterior superior/inferior
  • SCM
  • levator costorum
  • Latissimus dorsi
  • iliocostalis throacis + cervicis
  • QL
29
Q

What are the indirect abdominal effects of force inspiration?

A
  • increases intra-abdominal pressure
  • compresses abdominal viscera
30
Q

How does forced expiration occur?

A
  • internal intercostals
  • abdominals
  • transversus thoracis
31
Q

What are the direct abdominal effects of forced expiration?

A
  • depresses ribs
  • flexes thorax & sternum
32
Q

Explain how the costovertebral joints move during ventilation

A
  • AoR lies parallel with transverse processes
  • upper 6 perform the pump handle motion
  • lower 6 perform the bucket handle motion
33
Q

What is the pump handle motion?

A
  • more in an anterior to posterior fashion
  • upper 6 ribs that are connected to the sternum
34
Q

What is the bucket handle motion?

A
  • more medial to lateral motion
  • lower 6 ribs
35
Q

Explain how the sternocostal joints move during ventilation

A
  • bending/twisting of sternocostal joint cartilages

costochondral:
- permit little movement

chondrosternal:
- first rib -> very stable
- 2-7 -> synovial in nature; permits slight gliding motions

36
Q

How does the rib cage keep from collapsing during inspiration?

A
  • contraction of scalenes & external internal intercostals prevents collapsing
37
Q

What is paradoxical breathing?

A
  • describes the restriction rather than normal expanding of the rib cage
  • C4 spinal cord injury = paralyzing intercostals/abdominals
  • diaphragm then creates suction in chest which constricts upper thorax (especially in A&P direction)
  • usually presents w/ forward protrusion of abdomen during inspiration
  • intercostals will eventually become rigid & act as splint to thoracic wall
38
Q

Explain the pathomechanics of COPD

A
  • No elastic recoil -> air trapped in lungs -> thorax remains inflated (barrel chest) -> diaphragm chronically lowered -> changes resting length & line of force -> diaphragm draws ribs inward instead of lifting them outward
  • often use secondary muscles for breathing
39
Q

How does a closed upper extremity chain assist with breathing?

A
  • fixes distal attachments on arms (lats, pecs minor/major) which allows use of proximal attachments to act on ribs to help with ventilation
  • helps elevate sternum & ribs
40
Q

What are normal ROM’s for TMJ protrusion, lateral excursion, and opening?

A

Protrusion: 7mm

Lateral Excursion: 9mm

Opening: 43mm

Biomechanics Winter 2024 (6 decks)

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