Knee Joint Flashcards
Name the 2 joints in the knee?
Tibiofemoral & Patellofemoral
What is the femur covered by?
Hyaline Cartilage
What is the tibia covered by?
Articular Cartilage
The paatellofemoral joint is enclosed by the same capsule as the one that encloses the _______ .
“Knee joint proper”; femoraltibial joint
Communication can be seen between the knee joint space and the ______ .
Bursa (above it)
Do articular surfaces provide little or a lot of support?
Little (due to the shape)
Name the supporting structures of the knee joint
Cruciate ligament (ant & post), Collateral ligament (med & lat), Menisci (med & lat)
Describe the structure of the femur.
Distal end: has a surface with which the patella will articulate. The surface is reciprocally shaped (triangular)
Femur terminates as the condyles.
Describe the femoral condyles
They differ in shape.
Medial femoral condyle is longer than the lateral (Lateral is also wider).
The length is about 1cm different.
Why is it important that the condyles differ in size?
It’s important for when the joint is going from the flex -> ext position
What is between the condyles?
Intercondylar area (the notch is closer to the lateral side). It contains the ACL.
What can happen to the intercondylar area narrows?
The surrounding ligaments become irritated and frayed as it passes in the notch
Describe the tibial plateau
Medial surface is larger and longer, and the lateral surface is also shorter to correspond with lateral condyle of femur.
Are the structures in the tibial plateau articular or not?
They are non-articular. The region has an elevation in the centre. It is a site of attachment of two of the pairs of supporting structures.
It’s also the site of attachment of menisci and cruciate ligamnets
Describe when the knee extends
Femur rotates medially on fixed tibia, passive “screw-home” mechanism. This occurs in the last 15-20 degrees of extension.
Describe the ligaments during knee extension.
All ligaments are tight when the knee is extended. The Screw-home mechanism occurs about the ACL. Thus, ACL is most prone to injury if anything goes wrong while the knee extends.
Describe what happens when the knee flexes.
This is an active contraction of the Popliteus muscle.
Femur rotates laterally on flexed tibia. The rotation can only occur after the joint is unlocked.
Describe how the popliteus runs through the knee joint
It runs through the capsule, attaches to the tibia and passes up to attach to the lateral surface of condyle.
Describe the coloured areas
Purple: synovial membrane
Dark green: PCL (larger), ACL
Light green: capsule (incorporate the patellofemoral joint)
Blue: Menisci
Describe the movement of cruciate ligaments during development
They commence on the posterior aspect of the joint and migrate in. As they move forwards, they push the synovial membrane in front of them (but don’t become completely enclosed). Hence, they end up between ligament and membrane. Since synovial membrane is highly vascular; ACL tear -> bleeding.