L12: The lower limb; the knee Flashcards
the largest synovial joint in the body=
the knee
2 joints in the knee
patellofemoral
tibiofemoral
where do fractures on the tibial plateau nearly always happen
on the lateral side as the medial side is supported by bone
what does a sesamoid bone mean
it forms within a tendon
what does the patella enable
more efficient extension of the knee
genu valgum=
knees together
genu varum=
knees apart
what is the medial collateral ligament attached to
- part forms the capsule
- part inside the capsule is attached to the medial meniscus
what forces does the medial collateral ligament resist
valgus forces
is the lateral collateral ligament intracapsular
no (its extracapsular)
not attached to a meniscus
what forces does the LCL resist
varus forces
what kind of stability do cruciate ligaments provide
static stability
rotational stability
where are cruciate ligaments
intracapsular but extrasynovial
where does the anterior cruciate ligament attach
anterior intercondylar region of tibia and ascends posteriorly to femur
where does the posterior anterior cruciate ligament attach
posteriorly on the intercondylar region of the tibia and ascends anteriorly to attach to the femur in the intercondylar fossa
when is the anterior cruciate ligament taut
extension
what does the anterior cruciate ligament prevent
posterior displacement of femur on fixed tibia
tests for ACL rupture
Lachman’s test
anterior draw test
when is the PCL taut
in flexion
what does the posterior cruciate ligament prevent
prevents anterior displacement of femur on fixed tibia
when is PCL injured
blow to the knee whilst flexed
shape of medial menisci
C - cresent
shape of lateral menisci
O - oval shape
what is the medial menisci attached to
MCL
what is the lateral menisci attached to
popliteus tendon
which menisci is fixed
medial (lateral is mobile)
how are the menisci connected anteriorly
transverse ligament
3 things menisci do
- increased stability
- increased weight distribution
- decreased loading stress
what are menisci surrounded by
synovial fluid (they are within the capsule)
terrible triad =
torn medial collateral ligament, medial meniscus and ACL
knee locking mechanism=
- medial rotation of femur on tibia = screw-home locking mechanism
most stable knee position=
taut ligaments- ACL,MCL, oblique popliteal
key to the knee=
popliteus
what does popliteus do
- laterally rotates the tibia underneath the femur to unlock it
- simultaneously retracts lateral meniscus to prevent impaction
what does the deep 1/2 of popliteus do
helps pull the lateral meniscus out of the way
what does the superficial 1/2 of popliteus do
can pull the tibia in an internal rotation
innervation of popliteus
tibial nerve
the vastus muscles work only on_____
the knee
which quadricep works on the hip
rectus femoris
where do quadricep muscles come into
the patella tendon
where does the patella tendon insert into
tibial tuberosity
where does the iliotibial band run from and to
iliac crest to lateral tibial condyle
what is the iliotibial band
thickening of fascia lata
2 muscles the iliotibial band is acted on by
tensor fascia lata
gluteus maximus
what do the muscles acting on the iliotibial band do
pull knee into hyperextension
3 hamstrings
semitendinosus
semimembranosus
biceps femoris
what is pes anserinus
goose foot
3 muscles from each thigh compartment that attach on medial proximal aspect of tibia
- gracilis
- semitendinosus
- sartorius
which bursa of the knee if often inflamed in repetitive movement
suprapatellar bursa
what does the anterolateral ligament do
attach femur to tibia on lateral side
which direction of patellar dislocation is more likely
lateral dislocation
