Flashcards in Knee Joint Deck (32):
What kind of joint is the knee joint?
It's a modified hinge joint, allowing some rotation to change direction of movement
When can rotation occur at the knee joint?
when the knee is in flexion
Is the patella enclosed in the joint capsule?
What are the three paired structures for stability at the knee?
What's the functional difference between epicondyles and condyles of the femur
epicondyles are located laterally, for attachment of muscles
condyles are articular surfaces with condyles of tibia
T/F The lateral condyle is larger than the medial condyle
False, medial one is larger`
When does the screw-home mechanism occur?
When the knee is in terminal extension, and ACL pulls the femur in medially to lock
T/F Flexion is passive
false, flexion is active, extension is passive
what is the function of popliteus muscle
unlocking the knee joint by providing lateral rotation on the femur
Are cruciate ligaments intra-synovial?
No, they are extra-synovial, but intracapsular
Why doesn't the synovial membrane cover the whole menisci?
menisci is the point of articulation, and synovial membrane has rich neurovascular supply. It doesn't cover the whole menisci so irritation can be prevented
Why is there bleeding in the joint when a ligament in the capsule is torn
synovial membrane is likely to get damaged as well, so there is bleeding
What are the anterior muscle reinforcing the joint?
quadriceps, the femoris muscle
what are the lateral reinforcements of the joint?
popliteus, biceps femoris, iliotibial tract
What are the medial reinforcements of the joint?
pes anserinus, complex of tendons composed of satorius, gracilis, bursa, semitendinosus
What does "say grace before tea" stand for
Tendon of semitendinosus
What are the posterior reinforcements of the joint?
tendon of semimembranosus
Does the suprapatellar bursa communicate with the joint cavity?
Yes, so any infection can travel into the capsule
What are the attachments of ACL
anteriorly on the tibia
lateral condyle of femur
What are the attachments of the PCL
posteriorly on the tibia
medial condyle of femur
What is the action of ACL?
stops anterior displacement of tibia or posterior displacement of femur
In what situation in the ACL most commonly injured
upper leg rotates while lower leg is stationary
What is the test for PCL injury?
posterior draw test
What does the deep medial collateral ligament blend with
The medial meniscus
How does medial collateral ligament act as a secondary restrain for ACL
because the course of collateral ligament runs slightly anteriorly to prevent anterior displacement of tibia
What is the unhappy triad?
ACL, medial collateral ligament, medial meniscus. Usually damaged due to lateral rotational movement
What is the function of lateral collateral ligament
resisting medial movement of the tibia
What is the function of menisci?
distribute weight by increasing area of contact
Why is the medial meniscus more likely to be injured?
because it is held in place by the MCL
What are the two passive structures maintaining the patella alignment
raised lip on lateral femoral condyle
medial patellar retinaculum
What is the active structure maintaining patella alignment