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MSK 2 > 1i - TMJ anatomy > Flashcards

1i - TMJ anatomy Flashcards

1
Q

what is the most common complaint of someone w TMJ disorder

A

ear pain

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2
Q

what are examples of parafunctional habits

A

nail biting
clenching
grinding
lip biting
object biting
chewing gum
bruxism

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3
Q

what is bruxism

A

unconscious grinding, clenching teeth
- at night

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4
Q

what is a relevant characteristic of the TMJ capsule

A

thicker on outside

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5
Q

OIA of temporalis

A

O: entire temporal fossa
I: coronoid process & medial border of mandibular ramus

A: elevation, retrusion/retraction, ipsilateral lateral excursion (unilateral)

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6
Q

what is the main biting ms

A

temporalis

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7
Q

what are characteristics of the temporalis

A

thin but very large
dives behind zygomatic arch so can’t get to ms tendon junction

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8
Q

OI of masseter

A

superficial head
O: ant 2/3 of zygomatic arch
I: lat border of mandib angle

deep head
O: post 1/3 of zygomatic arch
I: superior border of mandibular ramus

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9
Q

actions of the masseter ms

A

elevation
ipsilateral lateral excursion (unilateral)

deep: retrusion/retraction
superficiala: protrusion

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10
Q

OI of medial pterygoid

A

O: lateral pterygoid plate of sphenoid bone and maxilla
I: medial surface of mandibular angle

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11
Q

what are the actions of the medial pterygoid

A

elevation
protrusion
contralateral lateral excursion (unilateral)

tonic contraction acts as a functional sling around angle of mandible

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12
Q

what holds the mandible in position

A

sphenomandibular lig needs a tonic contraction from the masseter, otherwise would just hang in fossa
- creates a functional sling

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13
Q

OI of lateral pterygoid

A

superior head
O: greater wing of sphenoid
I: disc

Inferior head
O: lateral border of sphenoid
I: condylar neck

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14
Q

what are the actions of the lateral pterygoid

A

protrusion (bilateral)
contralateral lateral excursion (unilateral)

superior: elevation
inferior: depression

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15
Q

what is the lateral pterygoid’s role in elevation

A

helps to eccentrically control disc tension and its position w closing

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16
Q

what is the lateral pterygoid’s role in depression

A

initiates open

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17
Q

what is the role of infrahyoid ms

A

stabilize the hyoid

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18
Q

what are the 4 infrahyoid ms

A

omohyoid
sternohyoid
sternothyroid
thyrohyoid

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19
Q

what are secondary ms to the TMJ and what is their role

A

infra and supra hyoids

aren’t directly acting on TMJ, but impact posture and way TMJ sits

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20
Q

what is the role of the suprahyoids

A

assist w mandibular depression

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21
Q

what are the 4 suprahyoid ms

A

digastric
geniohyoid
mylohyoid
stylohyoid

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22
Q

what are the primary ms innervated by and what are those ms

A

trigeminal (CN V) mandibular branch

masseter
temporalis
medial and lateral ptery
mylohyoid

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23
Q

what nerves innervate the secondary ms

A

hypoglossal n. (CN XII)
facial n. (CN VII)
ventral rami C1 via CN XII
ventral rami C1-3

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24
Q

what are the dermatomes relevant to the TMJ

A

C2-3: mandibular angle

mandibular branch of trigem (CN V) covers remainder of jaw

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25
Q

what are the mandible’s functional sling ms

A

masseter and medial pterygoid

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26
Q

what cervical ms impact the TMJ

A

suboccipital ms
SCM
scap ms
- UT, levator scap

27
Q

what cervical joints impact the TMJ

A

AO joint
cervical facet joints

28
Q

what ms are involved in elevation

A

masseter
temporalis
medial pterygoid
lateral pterygoid (superior fibers)

29
Q

what ms are involved with depression

A

lateral pterygoid (inferior fibers)
suprahyoids
infrahyoids

30
Q

what ms are involved with protrusion

A

masseter (superficial fibers)
medial pterygoid
lateral pterygoid

31
Q

what ms are involved w retrusion/retraction

A

masseter (deep fibers)
temporalis
suprahyoids (digastric)

32
Q

what ms are involved in lateral excursion

A

ipsi temporalis (uni contxn)
ipsi masseter (uni contxn)
contra med pterygoid (uni)
contra lat pterygoid (uni)

33
Q

what is the osseous articulation of the TMJ

A

superior aspect of mandibular condyle on mandibular fossa of the temporal bone

34
Q

what is the signficance of the coronoid process

A

important landmark for attachment poitns

35
Q

how is the fibrocartilage structured and what is the importance of this

A

high density collagen content which allows for repetitive forces thru jaw to be withstood

moving it constantly w talking, eating, swallowing
- have to withstand repetition and force of eating

36
Q

where is the fibrous capsule in relationship to the disc

A

fibrous capsule attaches to entire periphery of disc

37
Q

anterior articulations of the TMJ disc

A

temporal bone (articular eminence)
mandibular condyle
superior head of lat ptery

38
Q

posterior articulation of TMJ disc

A

retrodiscal lamina

39
Q

what is the main function of the fibrocartilage surrounding the TMJ disc

A

dissipate and endure loads and stresses

40
Q

why does the TMJ disc have such a high water content

A

dissipate forces

mobile when loaded
- if load front part of disc, water contents move post

41
Q

how does the thickness of the disc change and why

A

thin intermediate region
- accommodates convexity of condyle

thicker anteriorly and posteriorly
- maximize congruency to dec pressure

biconclave shape that accommodates the convexity of the joint and inc the surface area

42
Q

how does the vascularity and innervation change throughout the disc

A

thin intermediate region is avascular and not innervated
- can’t have pain which is good bc that is what contacts the fossa

thicker ant and post is vascular and innervated -> source of pain

43
Q

how does the elasticity change throughout the disc and how does this impact the functioning

A

superior portion elastic
- stretches w opening

inferior portion less elastic
- stabilizes joint

44
Q

what motions compose mastication

A

elevation and depression w lateral excursion and protrusion
- random and asymmetrical combo

45
Q

what does mastication cause at the jiont

A

joint compression

46
Q

what is mastication

A

tearing, chewing, and grinding motions via coordination of all ms

47
Q

what are the arthrokinematics of depression

A

early phase - post rotation
late phase
- rotation
- ant and inf translation of condyle and disc together

48
Q

when is there the greatest ligamentous tension in the TMJ joint

A

maximal opening

49
Q

how much motion is there in the early phase of depression

A

0-26mm

50
Q

how much motion is there in the late phase of depression

A

26-50mm

51
Q

what functions are possible with <10mm of depression

A

can only drink

52
Q

what functions are possible with 10-20mm of depression

A

push food in mouth

53
Q

what functions are possible with 20-30mm of depression

A

can eat food using fingers

54
Q

what functions are possible with 30-38mm of depression

A

can use fork and small pieces

55
Q

what functions are possible with >38mm of depression

A

can eat normally

56
Q

what initiates the arthrokinematics of elevation

A

tension in retrodiscal ligament

57
Q

what are the arthrokinematics of elevation

A

condylar head and disc translate post and superiorly

condylar body rotates ant

slight ant rotation of disc d/t eccentric contraction of superior head of lateral ptery (helps to sit back into place)

58
Q

what is the closed pack position of the TMJ

A

teeth clenched
- greatest joint congruency

59
Q

arthrokinematics of lateral excursion

A

ipsilateral condyle
- rotation/spine

contralateral condyle
- translation

60
Q

arthrokinematics of protrusion

A

ant translation

61
Q

arthrokinematics of retrusion

A

post translation

62
Q

what are protrusion and retrusion important components of respectively

A

protrusion - max opening
retrusion - max closing

63
Q

what ROM is necessary for protrusion and why

A

26mm
at the end range of opening

MSK 2 (20 decks)

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