B6.047 Hip, Knee, and Ankle Joints + Erect Stance and Walking Gait Flashcards
only motion in a healthy ankle joint
dorsiflexion
plantarflexion
where do eversion and inversion occur?
joints intrinsic to the foot
acetabulum
deep, bony socket
makes hip a very stable joint
surrounded by a soft tissue “o ring’ or ‘gasket’ to make it deeper
where is the head of the femur
NOT on the shaft
on the femoral neck
what is the “Q” angle
axis of femoral shaft is not aligned with gravity in the anatomical position
neck of femur is inclined about 120 deg with respect to the shaft
this creates an angle between the femoral shaft and the vertical line of gravity (the Q angle, about 18 deg)
what gender has a larger Q angle
female
pelvis is wider
where is bone density the greatest in hip joints
along lines of gravitational load
what is the iliofemoral ligament
thickest and strongest ligament in the body
thickening in the hip joint capsule that is named as a ligament
keeps trunk from flopping backwards
blood supply to the hip joint
retinacular arteries that stretch across the neck, sending twigs to the femoral head
most common hip injury in elderly
fracture of femoral neck
due largely to osteoporosis
retinacular blood vessels are highly susceptible to injury
most common hip complaints
OA
bursitis
multiple bursae situated around the hip joint including the greater trochanter
tuberculosis infection of the spine
can infiltrate the hip joint cavity via the capsule of the iliospsoas muscle, where it communicated with bursae and the joint cavity
patella
floating bone that serves as a pulley and an attachment site for tendons and ligaments at the knee
shape of femoral condyles
not perfectly circular
important for knee joint integrity (or laxity)
what leg bone receives the weight of the upper body
tibia alone
fibula not part of the knee joint
upper surface of tibial condyles
shallow depressions
receive femoral condyles
are the articular surfaces in the knee joint complex?
yup
can the articular surfaces in the knee joint be easily summarized?
nope
functions of the menisci
wafers of fibrocartilage on the tibial plateau
help center condyles of femur on tibia
1st line of defense to help create a stable knee joint
deep investing fascia of the thigh (fascia lata)
sleeve of dense connective tissue including the posterior and popliteal fascia
lateral and medial patellar retinacula
major thickenings of fascia that extend from the thigh across the knee to anchor into the crural fascia
fibular collateral ligament
stands apart from the joint capsule
attaches to lateral femoral condyle and head of fibula
thickenings in knee joint capsule
anterior -patellar ligament intrinsic -tibial collateral ligament -oblique popliteal ligament
what is the intrinsic joint capsule
stabilizes the posterior knee
dense, tough covering
deep to popliteal structures
tibial collateral ligament
attaches to medial epicondyle and medial tibia
attaches to medial meniscus, making it a part of the joint capsule
bursae in the synovial space
suprapatellar
prepatellar
infrapatellar
location of cruciate ligaments
outside the synovial space but within the fibrous joint capsule
named for their tibial attachments
function of PCL
resist forward displacement of the femur off of a fixed tibia when in flexion
function of ACL
resists backward displacement of a femur off of a fixed tibia when in extension
can ACL and PCL resist blows from the side?
no lol
poorly positioned
motions that can occur at the knee joint
flexion-extension
medial-lateral rotation
gliding-sliding
when during the gait is the femur fixed with a mobile tibia
swing phase
what happens during the last few degrees of leg extension during swing phase
lateral spin of the tibia on a fixed femur
difference in femoral condyle sizes
articular cartilage of the medial femoral condyle reaches further forward than the corresponding lateral cartilage
1 cm extra room
when is the knee joint more stable?
during extension
ligaments are tighter during extension
looser joint would be more susceptible to injury (flexed)
what is locking the knee?
resting femur onto tibia
not using any muscles
very little energy required in this position due to stability of joints
how do you unlock your knee joint?
shorten fibers of popliteus muscle when standing on a fixed tibia
femur rotates laterally
condyles of the femur spin on top of the tibia
function of healthy ankle joint
flexion and extension only
no medio-lateral or side to side motion
dozens of ligaments surround the joint to stabilize and resist side to side motion
where does side to side motion in the foot occur
sub talar joint (distal to ankle joint)
inversion and eversion occur here due to smooth upper surface of calcaneous
overlooked function of the interosseous membrane
stabilization of the ankle joint
most commonly injured joint in the body
ankle
usually due to excessive inversion injury involving fibular ligaments
why aren’t there ligament tears in the medial ankle as often?
deltoid ligament is so strong that the medial malleolus typically breaks instead of the ligament tearing
ankle sprain
abnormal loads that cause excessive side to side ankle movements can tear collateral ligaments, resulting in a sprain
ankle fracture
high velocity or overly powerful blows that involve twisting forces at the ankle lead to fracture, including avulsion of the lateral malleolus
pott’s fracture
common athletic injury
distal fibula snaps a few centimeters above the inferior tibiofibular joint
in severe eversion injury, medial malleolus is avulsed
axis of standing posture
axis of knee joint is behind the hip joint
trunk center of mass is in front of the knee
when standing in a knee locked posture, the weight of the upper body acts to keep the knee joint stable
why do humans often stand shifted onto one hip
minimize effort
can stand on their ligaments with very little muscle activity
tightening of iliotibial tract of the opposite thigh is one way to do this
unloaded limb maintains balance but does little active work
picture George’s gait
lol
what % of the gait is a double foot stance
60% stance phase
40% swing phase (1 foot off the ground)
ground reaction
generated to propel body mass forward
lengthen trailing limb to generate a pushing force by flexing the ankle and big toe
max walking speed
6 mph
3 mps
running gait needed to exceed this
why does the biceps femoris contract before heel strike
to slow down the limb
effect of high heels
change gait
extreme plantar flexion requires compensation
shoulders are pulled back with increased spinal curvature ( ass out ladies)
what determines gait width
femoral inclination angle
places human knees close together, angle smaller in females
function of gluteus medius and minimum
controlled pelvic tilt on unsupported side during normal gait
Trendelenburg sign
hip drop on the unsupported side caused by a loss of hip abductors on the supported side (drop is opposite side of injury)
pelvic rotation in gait
critical component
reduces side to side displacement of mass
running gait
leading limb fully flexed at the hip
both feet off the ground
most powerful ground reaction
spine has to be horizontal to the ground
similar to 4 footed vertebrates
