TMJ Kinematics Review Flashcards

1
Q

Cranial Nerves Mnemonics

A

Oh Oh Oh To Touch And Feel Virgin Girls Vaginas And Hymens

Some Say Marry Money But My Brother Says Big Boobs Matter More

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2
Q

What is wrong with saying “I have TMJ”

A

EVERYONE has TMJ bc its a joint→ actually TWO of them

We refer to it as TMD or TemporMandibular Disorder/Dysfunction

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3
Q

TMJ Structure

Mandibular Fossa and Articular Eminence

A
  • Articular Eminence
    • forms Anterior border of mandibular fossa and serves as point of functional contact for TMJ
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4
Q

TMJ Structure

Styloid Process

A

Attachments for muscles of tongue and pharynx and stylohyoid lig

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5
Q

TMJ Structure

Mastoid Process

A

Facial Nerve (CN VII) exits skull @ stylomastoid foramen

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6
Q

TMJ Structure

External Auditory Meatus→ Middle ear→ Inner ear

*Clinical Relevance?

A
  • TMJ dysf→ ear sx’s (due to direct pressure on ear, OR referral)
    • ear ache/pain
    • tinnitus
    • hypobaroacusis→ water in ear feeling
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7
Q

TMJ Structure

Mandible

A
  • U-shaped body
  • angle
  • vertically oriented rami→ ea. w/ condylar processes (head of mandible) and coronoid processes→ for attachment of temporalis tendon
    • Ant and Sup surface of head form articular surface for articulation w/ disc/articular eminence of temporal bone
    • Head narrows inferiorly (forming “neck”) for attachment of lateral pterygoid muscle
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8
Q

2 TMJs→ “Compound” joint

A
  • BOTH move simultaneously w/ any mandibular mvmt
    • swallowing, vocalizing, chewing
  • Articular surfs covered w/ fibrocartilage
    • protects from damage when sliding/translating
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9
Q

TMJ Structure

Articular Disc and Superior Head of Lateral Pterygoid

A

Lateral pterygoid attaches DIRECTLY to Biconcave articular disc ANTERIORLY

*see pics

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10
Q

Articular Disc

General Overview

A
  • Biconcave→ divides joint into upper/lower compartments
    • UPPER→ SUP surf of disc + articular eminence
    • LOWER→ INF surf of disc + condylar head
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11
Q

Biconcave articular disc divides TMJ joint into UPPER/LOWER compartments

explain…

A
  • UPPER→ SUP surf of disc + articular eminence
  • LOWER→ INF surf of disc + condylar head
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12
Q

Articular Disc

Capsular Attachements

A
  • Attached to medial and lateral aspects of capsule
  • Sup/Inf anterior caps ligs
  • Sup/Inf posterior caps ligs
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13
Q

Articular Disc

Attached MORE FIRMLY to ______

A

Head of mandible

  • Med/Lat bands→ aka medial and lateral collateral ligs
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14
Q

Articular Disc

ANT. margin attached to _______

A

Superior head of lateral pterygoid muscle

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15
Q

Articular Disc

Attachments allow for easy _________

A

Easy ANT. translation of disc

Limited POST glide

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16
Q

Bilaminar retrodiscal pad is essential what?

A

A posterior continuation of the disc

17
Q

Bilaminar Retrodiscal Pad

*post continuation of disc

A
  • Sup fibroelastic layer attach disc TO post aspect of mandibular fossa (temporal bone)
  • Inf INelastic layer attach disc TO condyle of mandible
  • Fuses w/ post aspect of TMJ capsule
  • Highly vascularized and innervated**
    • Clinical implications:
      • Retrodiscitis→ assoc’d w/ TMD
      • if overstretched→ can contribute to disc instability or derangements
        • sublux or disloc’s
        • Remember the hat will fall forward!!!
18
Q

TMJ Structure

Capsule

A
  • LOOSE Inferiorly
  • STRONG Laterally
  • Highly innervated
    • Clinical Imps:
      • Capsulitis
19
Q

TMJ Structure

Ligaments

Temporomandibular

A
  • Temporomandibular
    • Strong “suspensory” lig
    • Checks→ downward, post, lateral motion of mandible
20
Q

TMJ Structure

Ligaments

Stylomandibular and Sphenomandibular

A
  • Stylomandibular and Sphenomandibular
    • MINOR roles in stability
    • MAY help check protrusion of mandible
21
Q

TMJ Structure

Ligaments

Oto-ligaments

*think connect malleaus of middle ear TO TMJ

A
  • Malleomandibular
  • Disco-mallear
  • Clinical Implication
    • Connect inner ear→ mandible = ear sx’s
22
Q

TMJ Structure

Innervation

Trigeminal Nerve (CN V)

A
  • Trigeminal Nerve
    • Trigeminal-cervical complex
    • Clinical Implications?
      • TMJ probs cause pain in upper CS OR CS refers to TMJ
      • Direct neural relationship***
23
Q

TMJ

Muscles of Mastication

Everything***

A
  • ALL have somewhat oblique orientations relative to axis of TMJ
    • Masseter
    • Temporalis
      • ANT Vertical fibers→ mandibular elevation
      • INF Horizontal fibers→ ipsilateral lateral deviation
    • Med pterygoid
    • Lat pterygoid
      • *SUP head attached to ANT margin of disc
        • contracts ecc. during closing
  • Innervated by mandibular branch of Trigeminal N.
    • Clinical Implication: Trigeminal Neuralgia (Tic douloureux)
      • pain triggered by chewing
  • With chewing, only mandible moves
    • bc CS mm’s prevent head from moving→ act as stabilizers
24
Q

TMJ Rest Position

A
  • SOME mm activity req’d to keep mouth closed w/ body upright
  • Neg. Air Pressure @ point of contact b/w tongue and hard palate reduces mm forces needed to support jaw
    • Clinical Implication?
      • Clenching mm’s dont need to work as hard
  • Position: tongue up, teeth slightly apart, lips together
    • Say “EMMA” and bring lips together
25
Q

TMJ Kinematics:

Opening→ Mandibular DEPRESSION

AROM

A

40-55mm; normally symmetrical

26
Q

TMJ Kinematics:

Opening→ Mandibular DEPRESSION

Produced by:

A

Digastrics

Lateral pterygoid

Gravity

27
Q

TMJ Kinematics:

Opening→ Mandibular DEPRESSION

2 components

A
  1. Anterior Rotation of condyle UNDER disc (and/or post rotation of disc relative to condyle
    1. occurs in LOWER compartment
    2. accts for 11-25mm of opening
    3. in MOST→ this occurs FIRST, typ overlaps THEN FOLLOWED BY:
  2. Translation of disc/condyle complex
    1. occurs in UPPER compartment
    2. disc is firmly against head due to lig tension from rotation
    3. disc/condyle glides ANT and INF along articular eminence of temporal bone
    4. accts for remainder of opening
    5. retrodiscal pad limits excess forward motion of disc during translation
28
Q

TMJ Kinematics:

Opening→ Mandibular DEPRESSION

Abnormal Trajectories

*it is normal to be “abnormal”

A
  • Deviation
  • Deflection
    • does NOT return to middle
29
Q

TMJ Kinematics:

Closing→ Mandibular ELEVATION

Produced by:

A
  • Temporalis
  • Masseter
  • Medial pterygoid
30
Q

TMJ Kinematics:

Closing→ Mandibular ELEVATION

Everything else

A
  • Reverse kinematics of OPENING
    • FIRST
      • post/sup Translation of disc/condyle in UPPER COMPARTMENT followed by:
    • SECOND
      • post Rotation of condyle underneath disc in LOWER COMPARTMENT
  • Elastic fibers in the SUP lamina of bilaminar retrodiscal pad help return the disc to its POST pos after opening
  • SUP Head of Lat Pterygoid is ACTIVE (eccentrically) during closing to control posterior movement of disc
31
Q

TMJ

Protrusion

A
  • Controlled by bilateral action of Lateral Pterygoids, medial pterygoids, masseters
  • Forward movement→ Ant/Inf translation of disc/condyle in upper compartment of joint
  • “freeway space” req’d
32
Q

TMJ

Retrusion

A
  • Opposite of protrusion
  • Checked by:
    • ligamentous tension and space occupying function of bilaminar retrodiscal pad
  • Min. mm activity required to retrude
    • temporalis contributes
33
Q

TMJ

Lateral Deviation

ROM?

A

10-15mm each side

34
Q

TMJ

Lateral Deviation

controlled by:

A
  • Controlled by:
    • contralateral medial and lateral pterygoids
    • ipsilateral temporalis (post fibers)
    • ipsilateral lateral pterygoid
    • ipsilateral masseter
35
Q

TMJ

Lateral Deviation

further elaborate on movement…

A
  • Contralateral pterygoids
    • produce ANT/INF/MED translation of contralateral condyle
  • Ipsilateral temporalis (post fibers) and ipsilateral lateral pterygoid
    • Force Couple (2 mms acting on joint in opp. directions) acting on the ipsilateral condyle causing it to spin while the contralateral condyle translates ANT
36
Q

Frontal Plane tilting of mandible

A
  • allows for chewing of bolus
  • implications for JRFs?
    • Greatest on side where mandible moves UP
      • ex. if you chewing food on right side, the LEFT SIDE will have greatest JRFs!
37
Q

Mastication

A
  • Chewing stroke: elliptical loop of mandibular depression→ lateral dev→ elevation to help crush/grind food
  • Automatic and complex interplay of mms of mastication, tongue, suprahyoids, buccinator, and CS mm’s
    • working side→ chewing food
    • balancing side→ exp’s large compressive forces:
      • mm activity
      • lateral tilt of mandible
      • bolus on chew side→ narrows joint space on balancing side (non-chew side)
38
Q

TMJ

Relationship w/ Head/Neck Posture

A
  • FHP→ stretches ANT tissues including suprahyoids, tending to create a retrusive force
  • Chronic retrusion→ irritates retrodiscal pad→ inflammation→ pain