other joints of the ankle and foot Flashcards
foot is the
terminal joint of the lower kinetic chain
lower extremity should distribute and dissipate
compressive
tensile
shearing
rotary forces
what can inadequate distribution of forces lead to
abnormal movement
produces excessive stress
results in breakdown of connective tissue and muscles
what do the foot and ankle have to be
both mobile and stable
stable –> WB and gait
mobile
what do the foot and ankle have to be mobile
allow ground adaptation
shock absorption
compensate for rotation movements
allow ground adaptation
foot must adapt to the different surfaces we walk on
shock absorption
when the foot hits the ground
compensate for rotation movements
that occur proximally at the hip during gait
how is the ankle/foot complex divided
3 functional segments
3 fxnal segments of the ankle-foot complex
hind foot
mid foot
forefoot
hindfoot
posterior segment
hindfoot
posterior segment
talus and calcaneus
mid foot
middle segment
navicular, cuboid and 3 cuneiforms
forefoot
anterior segment
metatarsals and phalanges
talocalcaneonavicular joint
functional joint that ties together the talonavicular joint and the subtalar joint
talonavicular joint
head of the talus w/ the navicular
how does the calcaneus connected to the navicular
by the spring ligament
medial portion of the bifurcate ligament
function of the TCN
motion at the WB talus at one articulation will cause motion at the other articulations
what does the TCN do
helps what happens in the back of the foot occur in the front of the foot
mechanical link
transverse tarsal joint (midtarsal joint)
compound joint
formed by the talonavicular and calcaneocuboid joints
what do these two joints of the midtarsal joint form
“S-shape”
divides the hind foot from the midfoot and forefoot
midtarsal –> movement of the bones
cuboid and navicular are immobile in WB positions
in WB positions –> movement of the talus and calcaneus on the navicuolocuboid unit
calcaneocuboid joint
anterior calcaneus and the posterior aspect of the cuboid
has its own capsule that is reinforced by ligaments
ligaments of the midtarsal joint
lateral band of the bifurcate lig
dorsal calcaneocuboid lig
plantar calcaneocuboid (short plantar lig)
long plantar lig
long plantar lig –> midtarsal joint
attaches the back of the foot to the front of the foot
important for transverse tarsal joint stability
support of the longitudinal arch of the foot
fxn of the midtarsal joint
mechanically linked with TCN by a shared talonavicular joint
subtalar and TCN motion involves the entire transverse tarsal joint
when TCN is supinated and locked
transverse tarsal joint is also locked
when TCN is pronated and loose-packed
midtarsal joint is also mobile and loose packed
what is the transverse tarsal joint to the hind and forefoot
transitional link
will add supination and pronation
tarsometatarsal joints
plane synovial joints formed by the distal row and the base of the metatarsals
1st TMT
base of the first metatarsal w/ the medial cuneiform
has its own joint capsule
2nd TMT
base of the 2nd metatarsal w/ the middle cuneiform and the sides of the medial and lateral cuneiforms
strong and motion is more restricted = more stable
3rd TMT
base of 3rd metatarsal w/ the lateral cuneiform
shares a joint capsule with the 2nd TMT
4th and 5th TMT
bases of the 4th and 5th metatarsals with the cuboid
share a joint capsule
what reinforce each TMT joint
numerous dorsal, plantar and interosseous ligs
fxn of the TMTS
continuation of the transverse tarsal joint
will assist in regulating positions of the metatarsals and phalanges relative to the WB surface
if the transversetarsal joint motion is adequate
TMT join motion is not required
when rear foot motion is extreme
TMT join may rotate to provide further adjustment of forefoot position
Ray
fxnal unit formed by a metatarsal and its assocaited cuneiform
3 rays
1st ray
1MT w/ medial cuneiform
2nd ray
2nd MT w/ middle cuneiform
3rd ray
3rd MT w/ lateral cuneiform
4th and 5th rays
not associated w/ a cuneiform
formed by the metatarsal alone
TMT action
contribute to hollowing and flattening the foot
help compensate for read foot position if the transverse tarsal joint motion is not adequate
metatarsophalangeal joint (MTP)
condyloid synovial joints
2 degrees of freedom
allow for flexion/extension and ABD/ADD
1st MTP ROM
45 degrees of flexion
70 degrees of extension
why is adequate extension of first MTP important
late stand phase of gait
2-5th MTP ROM
approx 40 degrees of flexion and extension
sesamoid bones –> MTP
first MTP has two sesamoid bones
anatomic pulleys for the flexor hallucis brevis
protect the flexor hallucis longus from WB trauma
also share the WB load with the head of the first MT
MTP joint fxn
allow the foot to hinge at the toes
2 structural aspects of MTP that enhance hinging at toes
metatarsal break
plantar aponeurosis
metatarsal break
single oblique axis for MTP flexion/extension that passes through the 2-5 MT heads
oblique b/c MT get smaller as we go from 2-5
where the foot hinges when the heel rises
plantar aponeurosis
dense fascia that runs from the calcaneus to the toes
as the toes are extended @MTP –> the fascia is pulled tight
tension will draw the heal towards the toes and contribute to rigidity of the foot (windless mechanism) –> makes it more stable by pulling into supination
interphalangeal joint
synovial hinge joints
one degree of freedom
flexion/extension allowed
IP fxn
smooth weight shift to the opposite foot in gait
help maintain stability by pressing against the ground