knee Flashcards
2 joints of the knee
tibiofemoral patellofemoral
movements of the knee joint
flexion-extension rotation (during flexion only)
why is there no rotation of the knee during extension
because the ligaments of the knee are tight and wont allow rotation
what is the close packed position of the knee
extension (most stable)
3 support structures of the knee
cruciate ligaments collateral ligaments menisci
explain the shape of the articular surfaces of the femur
medial condyle is longer than lateral lateral condyle is wider than medial
what is the function of the notch in the intracondylar space of the femur
where the anterior cruciate ligament lies
explain the movement of the femur on the tibia during extension
the femur orates medially on the fixed tibia during the last 15-20 degrees of extension around tight ACL (passive screw-home mechanism)
explain the movement of the femur on the tibia during flexion
femur rotates laterally on the fixed tibia - requires active contraction of popliteus muscle
what are the structures that are enclosed in the knee joint capsule
- menisci - cruciate ligaments (intracapsular but extrasynovial) - synovial membrane - synovidal fluid
what are the anterior reinforcements of the capsule of the knee
the patellar tendon and retinacular fibres
what are the lateral reinforcements of the capsule of the knee
popliteus muscle biceps femoris muscle iliotibial tract
what is the medial reinforcement of the capsule of the knee
pes anserinus tendons
what is the posterior reinforcement of the capsule of the knee
oblique popliteal ligament
what are the muscle insertions of the pes anserinus tendons reinforcing the knee joint capsule
sartorius gracilis bursa semiTendinosus “Say Grace Before Tea”
explain the deficiencies in the knee joint capsule
2 deficiencies: - above patella for suprapatellar bursa - posteriorly for popliteus tendon and semimembranousus bursa
attachments of the ACL
from the anterior part of the tibia to the lateral condyle of the femur
attachments of the PCL
from the posterior tibia up to the medial condyle of the femur
functions of the ACL
(passively rotates lateral condyle in medial direction) - stops the tibia from being displaced anteriorly from the femur or the femur being displaced posteriorly from the tibia - assists internal rotation of the femur - contributes to locking in extension
function of the PCL
stops the femur from sliding forwards off the tibial plateau during extension and stops posterior displacement of the tibia during flexion
how does ACL injury occur
when rotation occurs laterally (opposite direction) during extension on a weight bearing leg
how does PCL injury occur
- fall on flexed knee - bumper bar impact
function of medial collateral ligament
- resists abduction forces of the knee and lateral rotation of the tiba - limits anterior displacement of the tibia when ACL damaged
why is it that when the medial collateral ligament is damaged you often get damage to the medial meniscus
because the medial collateral ligament deep fibres attach to the medial meniscus
