FORCES AND FUNCTIONAL ANATOMY HIGH YIELD

Question 1

what are the ground reactive forces?

Answer 1

vertical forces

linear/shear forces

Question 2

which of newtons laws is applicable to ground reactive forces?

Answer 2

newtons 3rd law

Question 3

what are the two peaks of the vertical force of ground reactive forces?

Answer 3

1st
peak at end of contact period when BW is supported by one foot when the heel and metatarsals are loaded

2nd
midway through propulsion

Question 4

what are the types of linear/shear forces?

Answer 4

contact (posterior shear force)

propulsion (anterior shear force)

Question 5

what stance do linear/shear forces occur?

Answer 5

stance phase of gait

Question 6

what happens during the contact portion of linear/shear forces?

Answer 6

heel strike causes posterior shearing when moving foot is stopped by ground friction

Question 7

what happens during the propulsion portion of linear/shear forces?

when does this peak

Answer 7

heel lift and push off of propulsion

soft tissue slides anterior relative to the metatarsal heads

fat pad under ball of foot disperses shear of propulsion

*all help for propulsion and peaks at the moment when the opposite foot contacts the ground

Question 8

when forces produce a turning effect, this is also observed as a moment and so is called?

Answer 8

torque

Question 9

T/F, the subtalar joint is a torque converter?

Answer 9

T

Question 10

what direction is the leg rotating during heel strike?

Answer 10

its internally rotating

Question 11

what is the effect of subtalar joint on torque?

on external rotation of leg?

Answer 11

it decreases it BUT
internal torque develops between the ground and sole of foot, peaks at early contact period

starts at midstance and internal torque develops again, this peak is larger than the first peak

Question 12

when does lateral shear peak?

Answer 12

end of contact period and peaks again during propulsion, clinically insignificant and caused bu shift in body weight

Question 13

what are the two primary factors in stability?

Answer 13

osseous structure
muscle activity

note that muscle resists abnormal motion of bone

Question 14

abnormal shear leads to what type of joint disorder? this leads too?

Answer 14

abnormal subtalar joint pronation

hypermobility

Question 15

the foot can be referred with respect to what two columns?

Answer 15

medial column

lateral column

Question 16

what does the medial column consist of?

Answer 16

the cuneiforms and metatarsals 1-3

Question 17

in the medial column, what dorsiflexes?

Answer 17

1st ray dorsiflexes to compensate for STJ pronation and to alleviate stress on sesamoids

4-6 degree dorsiflexion

Question 18

what does the lateral column consist of?

Answer 18

cuboid and metatarsals 4 and 5

Question 19

what is the importance of the lateral column?

Answer 19

balance for adapting to terrain

Question 20

what axis are involved in planal dominance?

Answer 20

vertical OMTJ axis

STJ axis

Question 21

what happens when the vertical OMTJ axis is deviated so that its more vertically oriented? significance?

Answer 21

the axis is more perpendicular to the transverse plane

we see more abduction/adduction of forefoot on the rear foot with pronation/supination of the OMTJ

Question 22

what is the affect when the STJ axis becomes more perpendicular to the transverse plane?

Answer 22

supination
ankle, knee, hip compensate
more transverse plane motion

Question 23

what is the affect when the STJ axis is deviated more horizontally becoming more perpendicular to the frontal plane?

Answer 23

more frontal plane motion as a result of more angulation

increased stability, hyper mobility, and subluxation

cyma line has anterior deviation at talonavicular joint and decreased calcaneal inclination on x-ray

Question 24

what is the affect of transverse deviation of the STJ?

Answer 24

so medial/lateral deviation leading to greater pronation and supination

Question 25

what are the important lateral ankle ligaments?

Answer 25

ATFL, PTFL, calcaneofibular ligaments

Question 26

what can result from lateral instability?

Answer 26

short lateral column or forefoot valgus causing calcaneus to invert to bring metatarsals to ground and inversion around the STJ

Question 27

structure is made of abductor hallucis, abductor digits minimi, plantar aponeurosis

make up the medial, lateral, central bands and attach at the plantar process of the calcaneus

Answer 27

plantar fascia

Question 28

this is associated with plantar aponeuorsis and is passive supination with no energy used?

Answer 28

windlass mechanism

Question 29

windlass mechanism is _____?

Answer 29

passive supination

Question 30

the oblique toe break is associated with what axis?

Answer 30

MPJ axis

Question 31

what degrees does MPJ motion need?

Answer 31

MPJs need approx 62 degrees (+/- 10 degrees) of dorsiflexion of lesser digits on lesser metatarsals heads

Question 32

this contributes to toebreak?

Answer 32

windlass mechanim

Question 33

ontogenetic dysfunction is compensated or uncompensated?

abnormal STJ loading?

Answer 33

compensated

yes!!

Question 34

what are the types of compensatory forefoot varus?

Answer 34

congenital
uncompensated
compensated
partially compensated

Question 35

name this compensatory ontogenetic dysfunction

foot can’t dorsiflex the 10 degrees needed at midstance

will see pronation at heel contact with equines

patient walks with knee flexed

heel lift in midstance due to tight gastroc, medial or lateral hamstring

Answer 35

equines

Question 36

name this compensatory ontogenetic dysfunction

congenital

compensates at MTJ by dorsiflexing the 1st ray or STJ supination

if MTJ we see lesions sub 2

if STJ we see lesions sub 1,5 or both

Answer 36

forefoot valgus

Question 37

name this compensatory ontogenetic dysfunction

plane of met head 1 and 5 everted to rearfoot

1st ray plantarflexed in relation to met heads 2-5

due to contracture state of peroneus or tight medial slips of plantar fascia

compensation is STJ supination, lesions seen under 1st and 5th metatarsal heads

Answer 37

plantar flexed 1st ray

Question 38

what are the types of abnormal STJ loading?

Answer 38

medial and lateral loading

Question 39

can be caused by external forces

obesity

tibial valgus

Answer 39

medial loading

Question 40

forces directed laterally due to inverted nature of calcaneus (what is this), and then so STJ pronates or supinates to get rest of foot on the ground

forefoot valgus or plantar flexed 1st ray directs forces laterally through the foot

Answer 40

lateral loading

Question 41

name the gear

prosed by Finn bojsen Moller

transverse axis made of met heads 1 and 2 and operates at high speed like for sprinting

Answer 41

high gear

Question 42

name the gear

oblique axis made of a line from met heads 2-5

operates for low speed power like for uphill climbing, carrying heavy loads

Answer 42

low gear

Question 43

when is low and high gear used? like in walking

Answer 43

initially in propulsion we use low gear axis then shift medially to high gear for the actual propulsion

both used

Question 44

what are the types of auto supports?

Answer 44

beams

truss

Question 45

this type of auto support resists bending

ends not secure so,

• foot can elongate during contact and midstance
• foot at contact becomes beam allowing motion at joints to adapt to terrain without bending the foot abnormally

Answer 45

beam

Question 46

this type of auto supports structure, braces it, makes it rigid

causes internal compression

ends are secured and so foot can’t elongate because of ground, osseous structure, phasic muscle activity plus windlass mechanism results in rigid lever for efficient propulsion

Answer 46

truss