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Biomechanics Exam 1 > First Ray > Flashcards

First Ray Flashcards

(90 cards)

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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
orientation of PL allows it to apply a --- and --pull to its insertion
plantar | lateral
26
the plantar pull allows the PL to --- the 1st ray or --- dorsiflexion of the 1st ray
plantarflex | resist
27
PL exerts a --- force that stabilizes the 1st ray on the navicular
posterior
28
PL exerts a --- force that stabilizes the 1st ray to the 2nd ray
lateral
29
subtalar joint pronation results in
medial column drops planatary | reduced plantarflexion moment of the PL on the 1st ray
30
more pronation of subtalar joint results in
less efficient at resisting dorsiflexory ground reactive forces unstable 1st ray
31
if the subtalar joint pronates enough to drop the medial column below the level of the cuboid, what happens to the PL
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
32
what happens to PL when the subtalar joint is pronated
PL can't provide plantarflexory moment on 1st ray | 1st ray is hypermobile
33
what is the biomechanics definition of hypermobility
a part that is moving when it should be stable | NOT increase ROM
34
when does 1st ray hypermobility occur
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
35
Kirby refers to 1st ray hypermobility as
lack of adequte 1st ray stiffness
36
hyermobility of 1st ray decreases the amount of
1st metatarsophalangeal joint dorsiflexion available
37
hypermobile 1st ray can lead to
1st MTPJ subluxation hallux limitus/rigidus hallux valgus
38
the width of the foot, particularly the forefoot, may have an effect on PL function by
increasing the length of the lever arm | makes the plantarflexion moment more effeicient
39
in order to have normal 1st ray function, the 1st MT head must be able to drop (plantarflex) below what
the plane of the MT heads 2-4
40
if the 1st ray can't plantar below the plane of MT heads 2-4 it can cause
hallux limitus
41
in order for the 1st ray plantarflexion to occur during gait
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
the calcaneus is represented by the calcaneal inclination angle, forms the
posterior aspect of the medial arch
43
the 1st ray is represented by the 1st MT declination angle, forms the
anterior aspect of the medial arch
44
the medial arch is partly maintained by
plantar fascia
45
plantar fascia is described as a
truss
46
what is a truss
a 3 sided structure w/ 2 compression sides (the calcaneus and the 1st ray) and 1 tension side (the plantar fascia)
47
as the subtalar joint pronates, the arch of the foot is
lowered and lengthened
48
increased length of the foot during subtalar joint pronation increases tension on the ---
plantar fascia
49
as the subtalar joint supinates what happens to the arch
arch comes up | tension on plantar fascia is reduced
50
what is the spanish windlass
incorporates the truss w/ a lever arm
51
the lever arm of the spanish windlass is the
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
1st MTPJ function is dependent on
proper function of 1st ray
53
anatomy of 1st MTPJ
comprised of: articular surfaces of the head of the 1st MT base of proximal phalanx of hte hallux medial and lateral sesamoids
54
what type of joint is the 1st MTPJ
biaxial
55
at the "transverse axis" of the 1st MTPJ motion occurs purely in what plane
sagittal plane
56
at the "vertical axis" of the 1st MTPJ motion occurs purely in what plane
transverse plane
57
what motion is available at the 1st MTPJ
dorsiflexion/plantarflexion | abduction/adduction
58
1st MTPJ ROM primarily in
sagittal plane motion
59
what degree of dorsiflexion of the 1st MTPJ is normal
65 °
60
the 1st 20-30° dorsiflexion on the 1st MTPJ is a result of what motion
pure rolling motion (ginglymus-type joint)
61
remaining 35° or greater dorsiflexion of 1st MTPJ occurs as a result of
1st ray plantarflexion allowing the base of the proximal phalanx to slide up and over the 1st MT head
62
what allows for sliding motion of the 1st MTPJ
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
during gait, the hallux is in a --- position
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
the Spanish windlass effect of the 1st MTPJ during gait lifts
the heel instead of the hallux
65
the spanish windlass effect of the 1st MTPJ during gait is normal if
the subtalar joint is supinating as the heel is listed | foot will be allowed to move over the hallux
66
the spanish windlass effect of the 1st MTPJ during gait is abnormal if
the heel is lifting, but the subtalar joint is pronating, tension on the plantar fascia will prevent proper dorsiflexion of the hallux
67
at push-off before the digits leave the floor the tibia is --- degrees anterior to vertical
45°
68
at push-off before the digits leave the floor the ankle joint is plantarflexed --- degrees
20°
69
what is the minimum amount of 1st MTPJ dorsiflexion required for normal gait
65 °
70
5th ray
5th MT | independent axis of motion
71
what type of joint is the 5th ray
uniaxial | triplanar
72
what motion does the 5th ray provide
pronation | supination
73
how is the 5th ray axis oriented
posterior, lateral, plantar to anterior, medial dorsal
74
5th ray axis is located: - - from transverse plane - - from the sagittal plane - - from frontal plane
20° 35° 70°
75
how do you measure 5th ray
measured relative to the plane of MT heads 2-4
76
5th ray axis is deviated greatest from
frontal plane, but motion that is measured is sagittal plane motion
77
where is the neutral position of the 5th ray
at its centre of ROM
78
NOTE
the function of the 5th ray during locomotion is not understood
79
rays 2 and 3 include
the MT and the corresponding cuneiform
80
ray 4 includes
MT 4
81
ray 2-4 provide purely --- plane motion
sagittal
82
during stance phase in a normal foot, rays 2-4 should be
maximally dorsiflexed | some plantarflexion motion is required during propulsion to allow for dorsiflexion of the associated MTPs
83
lesser MTPJ have similar motion to
1st MTPJ except less ROM is required for normal gait (b/c they leave the ground earlier than the 1st)
84
lesser MTPJ joints have vertical and horizontal axes providing --- and --- plane motion
transverse sagittal (bi-axial)
85
the deep transverse ligament of the lesser MTPJ may function similarly to
the sesamoids by allowing the MT heads to glide posteriorly as the lesser ray plantarflex
86
motion at the interphalangeal joint occurs about --- axes located in the phalax shaft just proximal to the joint
transverse
87
the axis of the digits is horizontal and provides --- plane motion
sagittal
88
the motion of the digits that occur is in the direction of
plantarflexion | no dorsiflexion beyond fully extended
89
minimal motion of the digits is required during gait bc the digits should be
fully extended during the propulsive phase
90
--- plays an important role in assisting the FDL and FDB in stabilizing the digits
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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