Lecture 13: Ankle and Foot Arthrology and Musculature (Test 3) Flashcards
describe the midtarsals or Chopart’s joint
consists of talonavicular and calcaneocuboid joints
very versatile; 3 planes of movement
allows weight bearing foot to adapt/contour
functions closely with subtalar joint to allow for supination/pronaiton
describe the talonavicular joint
resembles a ball and socket (convex talus and concave navicular/spring ligament)
motion at talonavicular joint
provides substantial mobility to medial and lognitudinal column with twisting and bending of midfoot to rearfoot (Inversion/eversion and flexion/extension)
describe the calcaneocuboid joint
less motion than the talonavicular joint
provides stability to lateral foot
supported by ligaments
describe how the transverse tarsal joint moves
moves with subtalar (can isolate by holding calcaneus in place)
navicular spins at talonavicular joint
allows calcaneus to move and both the subtalar and transverse tarsal joints to provide pronation and supination
describe how the rearfoot directs the transverse tarsal joint of the foot with pronation and supination
full supination restricts overall flexibility of the midfoot (lateral side drops/twists and is more rigid)
full pronation increases overall flexibility of the forefoot (untwists medial and lateral near foot; nearly parallel)
axis of the transverse tarsal joint
2 seperate ones
longitudinal (almost anterior/posterior) for inversion and eversion
oblique (vertical/medial) for abduction/DF and adduction/PF
inversion and eversion ROM present at the transverse tarsal joint
20-25 inversion
10-15 eversion
inversion arthrokinematics of the transverse tarsak joint
spin of navicular around the conves head of the talus
lifts the medial arch
pull via post tibialis
eversion = reverse with pull of peroneus
purpose of the medial longitudinal arch
primary load bearing/shock absorbing structure
bones making up medial longitudinal arch
calcaneus
talus
navicular
cuneiforms
3 medial metatarsals
what would happen if there was no medial longitudinal arch
the large/rapid loading forces of running would exceed physiological weight bearing capacity of the bones
what structures assist in load absorption of the medial longitudinal arch
fat pads
sesamoids
olantar fascia
when are small vs high muscle forces required for the medial long arch support
quiet standing = small
high stresses of jumping/tip toes/running = large forces
describe the plantar fascia
primary passive support for arch
dense connective tissue in superficial and deep platers
2-2.5 mm thick
longitudinal/transverse collagen fibers
very strong
blends with first layer of intrinsic muscles
strength of plantar fascia
can withstand 810 N (180lbs)
where do the central bands of the plantar fascia blend
into metatarsal heads and with plantar plates and ligaments of the MTP joints, flexor tendon sheaths, and fascia of toes
extension of the toes stretches the central fibers of the plantar fascia and this puts stress on what
tension on the medial arch
in normal stance how is body weigth spread out
through talonavicular joint and spreads out to fat pads and thick dermis over metatarsal heads and heel
describe the comressive forces of the rearfoor and forefoot
rear = 2x compressive force as the forefoot
in forefoot, it is generally greatest at the heads of the 2nd and 3rd metatarsals
cutting plantar fascia decreases arch stiffness by how mcuh
25%
describe what happens at the arch of the foot during standing
BW pushes talus inferiorly and lowers arch
tension in fascia acts as a spring
when arch is depressed the rearfoot pronates a few degrees
what is pes planus
flat foot/dropped medial arch
due to joint laxity combined with overstretched/torn/weak fascia, spring ligament, or posterior tibialis
results in excessive subtalar pronation
forefoot abduction can occur and depress talis and make the navicular rib against inside of foot
Importance of subtalar joint in gair cycle
drives foot to capacity to transform it from a rigid lever to a flexible shock absorber
how is the ST joint adding flexibility to the foot in the gait cycle
during first 30-35% it pronates (everts)
how does the foot transfer to stabilitvs flexibility in the late phase of gait
arch rises sharply and supinates addign stability to the foot
how does the subtalar joint move immedialtely after heel contact in the early to midstance portion of gait
rapidly plantar flexes and pronates 4-9 degrees
calcaneus everts and pronates in response to the GRF just lateral to midpoint of calcaneus
head of talus pushes medially and inferior
ST joint prontates
AND tibia and fibula internally rotate after heel contact
What happens if there is excessive pronation at the stance phase
center of pressure falls medially
this can stress tissue ; especially the fascia, talonavicular joint, and posterior tibialis tendon
can involve muscle weakness in foot/arch or laxity in arch structures
may have excessive subtalar motion in horizontal and frontal planes
when in the gait cycle does the entire stance limb begin to reverse the hroizontal plane motion from internal to external RT
15-20% into gait cycle
describe how the stance leg shifts from IR to ER in the gait cycle
stance foot is secured
ER of femur then tibia
talus reverses into ER
then subtalar joint moves toward supination
mid and forefoot still in contact with floor for push off
then mid and forefoot move into relative pronation
medial and longitudinal arch are lifted and mid/forefoot move into rigid supination which allows the force of the muscles to transfer into the push off
theory for orthosis to prevent excessive pronation
theory is that it optimizes mid stance alignment to reduce musculature demands and optimize bony alognment
in order to use you need sufficient mobility, good eccentric control of post tib, and good mobility in forefoot
what joints for the transverse arch
3 at the cuneonavicular and 1 at calcaneocuboid
what are lisfrancs joints
seperate fore and mid foot
from the base of the metatarsals to teh cuneiforms/cuboids
least motion is found at the 2nd/3rd
describe the intermetatarsal joints
have plantar, dorsal, and interosseous ligaments
3 lateral are synovial joints
the 1st and second are NOT synovial
describe the metatarsal phalangeal joints
convex head of the metatarsals to shalow concavity of the phalanx
have a capsule, collateral ligamentsl and a plantar plate (passage for flexor tendons)
2 deg of freedom: flex/ext and abd/add
what is halluz limitus or rigidus or turf toe
marked limited in motion and pain at MTP (<55 deG)
need 45 deg for walking so pt may adapt by walking on outside of foot
caused by frequent forceful hyperext
can cause sesamoid fx
what is hallux valgus
progressive lateral deviation of great toe/adduction of metatarsal
tendons are displaced relative to joint and can promote greater deformation
tigh achilles, incorrect footwear, excessive rearfoot valgus, instability of 1st ray can be causative and secondarily can get hemmer 2nd toe, metatarsalgia, and bursitis at “bunion”
describe the interphalangeal joints
proximal and distal IPs
convex head and convex base of distal one
have ligamens/capsules/plates
flex and extend
important for windless mechanism where fascia transmits force from calcaneus to base of toes for push off
describe the windless effect
contraction of extrinisc platar muscles lifts calcaneus
BW is transferred over metatarsal heads
resulting extension stretches/winds up plantar fascia
increased tension raises arch and strengthens mid and fore foot
intrinsic muscles also reinforce arch
how does flat foot affect the windless effect
medial arch is poorly supported
forfoot sags when going onto toes
this reduced the extension of the MTP joints and limits the usefullness of the windless effect
arch remains flat and midfoot is unstable as a result
difference between extrinsic and intrinsic muscles of the leg
extrinsic only have proximal attachment in leg
intrinsic have proximal and distal attachments in leg
roots of common fibular n
L4-S2
muscles that contribute to DF and inversion
tibialis anterior
extensor hallucis longus
tibial n roots and innervation
L4-S3
muscles that contribute to DF and eversion
extensor digitorum longus
peroneus tertius
muscles that contribute to PF and inversion
tibialis post
flexor digitorum longus
flexor hallucis longus
achilles tendon
muscles that contribute to PF and eversion
peroneus brevis and longus
what muscles are in the anterior compartment of the leg
tibialis anterior
extensor hallucis longus
extensor digitorum longus
peroneus tertius
what is in the lateral compartment of the leg
peroneus longus and brevis
where do peroneus longus and brevis run
from the lateral fibula they wrap around the lateral malleolus (acts as a pully)
brevis attaches to 5th metatarsal head
longus runs through the groove of the cuboid bone between the long and short plantar ligaments to the 1st tarsometatarsal joint
what is on either side of the 1st metatarsal
anterior tibialis and peroneus longus
importance of peroneus longus and brevis functionally
primary evertors
main source of active stability of ankle and they stabilize the first ray
they are active through much of the gait cycle
-eccentric following heel strike, midstance, and heel off
what muscles form a sling that supports the transverse arch and medial longitudinal arch
fibularis longus and tibialis posterior
what do gastroc and tibialis posterior do when someone runs on tip toes
their pull causes a slight supination of the rearfoot which adds further stability to the foot
what is the superficial group of the posterior compartment of the leg
gastroc
soleus
achilles
plataris
what is in the deep group of the posterior compartment of the leg
posterior tib
flexor digitorum longus
flexor hallucis longus
characteristics of the achilles tendon
strongest tendon in the body
75% of ruptures are people over 55
it is compliant and can store energy when stretched
describe how there is a large mechanical advantage for the gastroc when standing on tip toes
gastroc has short internal moment arm from the talocrural joint
gastroc has long internal moment arm on metatarsophalangeal joints
once on tip toes, LOG falls posterior to axis of MTP joints; thus body weight acts with relatively small external moment arm
what is the one layer of intrinsic muscles on the dorsum of the foot
extensor digitorum brevis
what are the layers of intrinsic mucsles on the plantar surface
layer 1: Flexor digitorum brevis, abductor hallucis, and abductor digiti minimi
layer 2: Quadratus plantae, lumbricals
layer 3: adductor hallucis, flexor hallucis brevis, flexor digiti minimi
layer 4: plantar interossei and DI??
a weakened soleus can cause what problem with knee flexion while standing with foot on ground
weak soleus cant decelerate DF
