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Biomechanics Exam 1 > First Ray > Flashcards

First Ray Flashcards

1
Q

the biomechanical definition of the 1st ray includes

A

1st MT
1st cuneiform
articularions btwn the navicular-cuneiform joint
MT-cuneiform joint

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2
Q

surgical definition of the 1st ray does not include what

A

the cuneiform

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3
Q

the axes for the navicular-cuneiform joint and the MT-cuneiform joint are

A

equal

motion in one joint does not occur w/o motion in the other - therefore they are treated as one unit

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4
Q

very little motion occurs at what joint (navicular cuneiform or MT-cuneiform)

A

MT-cuneiform

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5
Q

what type of joint is the 1st ray

A

uniaxial

triplanar

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6
Q

the 1st ray axis is in what direction

A

axis passes anterior, lateral and plantar to posterior, medial and dorsal

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7
Q

does the 1st ray provide for pronation and supination

A

NO

axis is directed opposite to those joints that provide pronation and supination

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8
Q

1st ray axis is deviated — from sagittal and frontal planes allowing for — amounts of inversion w/ dorsiflexion and eversion w/ plantarflexion

A

45

equal

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9
Q

1st ray is deviated — from the transverse plane allowing for what

A

9

adduction with inversion/ dorsiflexion and slight abduction w/ eversion/plantarflexion

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10
Q

1st ray axis is independent of the

A

lesser ray axes

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11
Q

neutral position of the 1st ray axis is at

A

the centre of its ROM (evaluated in the sagittal plane)

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12
Q

how do you calculate the neutral position of the 1st ray

A

subtract the amount of dorsiflexion MINUS amount of plantarflexion DIVIDE by 2

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13
Q

how do you measure the 1st ray ROM

A

compare excursion of 1st ray dorsally and plantarly relative to plane of 2nd through 4th MT heads w/ subtalar neutral position and the midtarsal joint maximally pronated

remember: equal amounts of inversion and eversion are also occuring

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14
Q

total range of motion of 1st ray should be

A

1cm with 1/2 cm in direction of dorsiflexion and 1/2 cm in the direction of plantarflexion

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15
Q

minimum ROM of 1st ray

A

for gait is not known

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16
Q

***first ray function is very dependent upon

A

position of other joints, particularly the subtalar joint:
PL function is dependent upon normal subtalar joint function
1st ray function is dependent upon normal PL function

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17
Q

PL applies a — and — force to the 1st ray

A

plantarflexion

abduction

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18
Q

in OKC the PL — the 1st ray and the ankle joint — the subtalar joint

A

plantarflexes

pronates

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19
Q

*in CKC PL applies a — moment to the 1st ray but a — moment at the subtalar joint

A

plantarflexion

supination

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20
Q

in CKC the 1st ray cannot plantarflex through the floor, instead the proximal aspect of the 1st ray is

A

raised

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21
Q

as the medial column is elevated, the talus is

A

dorsiflexed

a component of CKC subtalar joint supination and ankle joint pronation

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22
Q

PL may initiate — during the gait cycle, and stabilizes the 1st ray against the ground

A

resupination

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23
Q

peroneus longus passes — and — to the cuboid

A

lateral

inferior

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24
Q

PL passes — and — to its insertion at the base of the 1st MT and medial cuneiform

A

suepriorly

medially

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25
Q

orientation of PL allows it to apply a — and –pull to its insertion

A

plantar

lateral

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26
Q

the plantar pull allows the PL to — the 1st ray or — dorsiflexion of the 1st ray

A

plantarflex

resist

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27
Q

PL exerts a — force that stabilizes the 1st ray on the navicular

A

posterior

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28
Q

PL exerts a — force that stabilizes the 1st ray to the 2nd ray

A

lateral

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29
Q

subtalar joint pronation results in

A

medial column drops planatary

reduced plantarflexion moment of the PL on the 1st ray

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30
Q

more pronation of subtalar joint results in

A

less efficient at resisting dorsiflexory ground reactive forces
unstable 1st ray

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31
Q

if the subtalar joint pronates enough to drop the medial column below the level of the cuboid, what happens to the PL

A

the PL as it passes around the cuboid will not be dorsal to its insertion
will then pass dorsal lateral to planar medial
may apply a dorsiflexory force on the 1st ray

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32
Q

what happens to PL when the subtalar joint is pronated

A

PL can’t provide plantarflexory moment on 1st ray

1st ray is hypermobile

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33
Q

what is the biomechanics definition of hypermobility

A

a part that is moving when it should be stable

NOT increase ROM

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34
Q

when does 1st ray hypermobility occur

A

when the subtalar joint is excessively pronated, the PL loses its pull allowing the 1st ray to dorsiflex when it should be stable against the ground

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35
Q

Kirby refers to 1st ray hypermobility as

A

lack of adequte 1st ray stiffness

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36
Q

hyermobility of 1st ray decreases the amount of

A

1st metatarsophalangeal joint dorsiflexion available

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37
Q

hypermobile 1st ray can lead to

A

1st MTPJ subluxation
hallux limitus/rigidus
hallux valgus

38
Q

the width of the foot, particularly the forefoot, may have an effect on PL function by

A

increasing the length of the lever arm

makes the plantarflexion moment more effeicient

39
Q

in order to have normal 1st ray function, the 1st MT head must be able to drop (plantarflex) below what

A

the plane of the MT heads 2-4

40
Q

if the 1st ray can’t plantar below the plane of MT heads 2-4 it can cause

A

hallux limitus

41
Q

in order for the 1st ray plantarflexion to occur during gait

A

The subtalar joint needs to be supinated
The heel needs to lift
The sesamoids must function properly
The second metatarsal should be longer than the first

42
Q

the calcaneus is represented by the calcaneal inclination angle, forms the

A

posterior aspect of the medial arch

43
Q

the 1st ray is represented by the 1st MT declination angle, forms the

A

anterior aspect of the medial arch

44
Q

the medial arch is partly maintained by

A

plantar fascia

45
Q

plantar fascia is described as a

A

truss

46
Q

what is a truss

A

a 3 sided structure w/ 2 compression sides (the calcaneus and the 1st ray) and 1 tension side (the plantar fascia)

47
Q

as the subtalar joint pronates, the arch of the foot is

A

lowered and lengthened

48
Q

increased length of the foot during subtalar joint pronation increases tension on the —

A

plantar fascia

49
Q

as the subtalar joint supinates what happens to the arch

A

arch comes up

tension on plantar fascia is reduced

50
Q

what is the spanish windlass

A

incorporates the truss w/ a lever arm

51
Q

the lever arm of the spanish windlass is the

A

hallux
The hallux can dorsiflex much easier when the subtalar joint is supinated and tension on the plantar fascia is reduced
If the foot is pronated, tension is increased on the plantar fascia, and hallux dorsiflexion range of motion will be reduced

52
Q

1st MTPJ function is dependent on

A

proper function of 1st ray

53
Q

anatomy of 1st MTPJ

A

comprised of:
articular surfaces of the head of the 1st MT
base of proximal phalanx of hte hallux
medial and lateral sesamoids

54
Q

what type of joint is the 1st MTPJ

A

biaxial

55
Q

at the “transverse axis” of the 1st MTPJ motion occurs purely in what plane

A

sagittal plane

56
Q

at the “vertical axis” of the 1st MTPJ motion occurs purely in what plane

A

transverse plane

57
Q

what motion is available at the 1st MTPJ

A

dorsiflexion/plantarflexion

abduction/adduction

58
Q

1st MTPJ ROM primarily in

A

sagittal plane motion

59
Q

what degree of dorsiflexion of the 1st MTPJ is normal

A

65 °

60
Q

the 1st 20-30° dorsiflexion on the 1st MTPJ is a result of what motion

A

pure rolling motion (ginglymus-type joint)

61
Q

remaining 35° or greater dorsiflexion of 1st MTPJ occurs as a result of

A

1st ray plantarflexion allowing the base of the proximal phalanx to slide up and over the 1st MT head

62
Q

what allows for sliding motion of the 1st MTPJ

A

The instantaneous axis of rotation moves more superiorly and posteriorly within the metatarsal head
With plantarflexion of the first ray, the 1st metatarsal head also glides posteriorly on the sesamoids

63
Q

during gait, the hallux is in a — position

A

fixed
The rest of the body must then pass over the hallux
Movement of the proximal segment of the joint allows for the motion

64
Q

the Spanish windlass effect of the 1st MTPJ during gait lifts

A

the heel instead of the hallux

65
Q

the spanish windlass effect of the 1st MTPJ during gait is normal if

A

the subtalar joint is supinating as the heel is listed

foot will be allowed to move over the hallux

66
Q

the spanish windlass effect of the 1st MTPJ during gait is abnormal if

A

the heel is lifting, but the subtalar joint is pronating, tension on the plantar fascia will prevent proper dorsiflexion of the hallux

67
Q

at push-off before the digits leave the floor the tibia is — degrees anterior to vertical

A

45°

68
Q

at push-off before the digits leave the floor the ankle joint is plantarflexed — degrees

A

20°

69
Q

what is the minimum amount of 1st MTPJ dorsiflexion required for normal gait

A

65 °

70
Q

5th ray

A

5th MT

independent axis of motion

71
Q

what type of joint is the 5th ray

A

uniaxial

triplanar

72
Q

what motion does the 5th ray provide

A

pronation

supination

73
Q

how is the 5th ray axis oriented

A

posterior, lateral, plantar to anterior, medial dorsal

74
Q

5th ray axis is located:

    • from transverse plane
    • from the sagittal plane
    • from frontal plane
A

20°
35°
70°

75
Q

how do you measure 5th ray

A

measured relative to the plane of MT heads 2-4

76
Q

5th ray axis is deviated greatest from

A

frontal plane, but motion that is measured is sagittal plane motion

77
Q

where is the neutral position of the 5th ray

A

at its centre of ROM

78
Q

NOTE

A

the function of the 5th ray during locomotion is not understood

79
Q

rays 2 and 3 include

A

the MT and the corresponding cuneiform

80
Q

ray 4 includes

A

MT 4

81
Q

ray 2-4 provide purely — plane motion

A

sagittal

82
Q

during stance phase in a normal foot, rays 2-4 should be

A

maximally dorsiflexed

some plantarflexion motion is required during propulsion to allow for dorsiflexion of the associated MTPs

83
Q

lesser MTPJ have similar motion to

A

1st MTPJ except less ROM is required for normal gait (b/c they leave the ground earlier than the 1st)

84
Q

lesser MTPJ joints have vertical and horizontal axes providing — and — plane motion

A

transverse
sagittal
(bi-axial)

85
Q

the deep transverse ligament of the lesser MTPJ may function similarly to

A

the sesamoids by allowing the MT heads to glide posteriorly as the lesser ray plantarflex

86
Q

motion at the interphalangeal joint occurs about — axes located in the phalax shaft just proximal to the joint

A

transverse

87
Q

the axis of the digits is horizontal and provides — plane motion

A

sagittal

88
Q

the motion of the digits that occur is in the direction of

A

plantarflexion

no dorsiflexion beyond fully extended

89
Q

minimal motion of the digits is required during gait bc the digits should be

A

fully extended during the propulsive phase

90
Q

— plays an important role in assisting the FDL and FDB in stabilizing the digits

A

intrinsic musculature
Consider the wing and sling mechanisms
Consider the role of plantar and dorsal interossei
Consider the powerful dorsifexory force provided by the long extensors

Biomechanics Exam 1 (12 decks)

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