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Z MD1 Hip and leg anatomy > knee > Flashcards

Flashcards in knee Deck (32):

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


how does MCL injury occur

usually with a rotational injury with a force in a lateral direction


function of lateral collateral ligament

resists adduction forces (movement medially of the tiba in respect to the femur)


why is the LCL not as often damaged compared to the MCL

because it is separated from the joint by the tendon of popliteus


function of the menisci of the knee joint

- shock absorb - weight distribution


why is the medial meniscus more commonly injured compared to the lateral

- attachment to MCL - longer - horns are further apart - less mobile


what is the normal alignment of the patellofemoral joint maintained by

- vastus medialis muscle (active) - medial patellar retinaculum (passive) - raised lip on lateral femoral condyle (passive)


how does dislocation of the patella occur

patella pulled laterally by the strong quadriceps muscle


how does chondromalacia patella predispose to subluxation/dislocation of the patella

because there is a mechanical problem of tracking of the patella in the femoral groove due to degeneration of cartilage