Lab 3-5 Flashcards
Ultrastructural features of the tubular components of the nephron
Proximal convoluted tubule
Distal convoluted tubule
Loop of Henle
Collecting duct
Effect of the popliteus muscle on the femur (in relation to the tibia) when this muscle contracts
Medial (internal) rotation of the tibia on the femur in non-weight-bearing conditions (open-chain).
Lateral (external) rotation of the femur on the tibia in weight-bearing conditions (closed-chain).
Attachment of biceps femoris in humans
Lateral condyle of tibia
What happens to the point of articulation between the femoral and tibial condyles during knee flexion?
The contact points move posteriorly on the tibial plateau as the femoral condyles roll backward and slide forward.
What happens to the point of articulation between the femoral and tibial condyles during knee extension?
The contact points move anteriorly on the tibial plateau as the femoral condyles roll forward and slide backward.
Where are the contact points located during deep knee flexion (beyond 90 degrees)?
The posterior portions of the femoral condyles are in contact with the tibial plateau.
Where are the contact points located in full knee extension?
The anterior portions of the femoral condyles are in contact with the tibial plateau.
How do the contact points move from full extension to 90 degrees flexion?
The contact points shift from the anterior to the posterior regions of the femoral condyles.
Why is the variation in contact points important for joint stability?
The coordinated rolling and gliding movements help maintain joint stability and distribute loads across different areas of the cartilage, reducing wear and tear.
How does the variation in contact points affect the knee’s range of motion?
It allows a smooth transition between flexion and extension, facilitating the full range of knee motion.
What role do the menisci play in relation to the changing contact points during knee movement?
The menisci adjust their position and shape to enhance congruence and absorb shock, accommodating the changes in contact points.
When is the knee joint most stable and why?
The knee joint is most stable in full extension because the collateral and cruciate ligaments are taut, the bony congruence between the femur and tibia is optimal, the menisci are positioned to distribute load evenly, the joint capsule is tight, and stabilizing muscles like the quadriceps are activated.
Why can’t the femur and tibia be separated when the patella is removed and collateral ligaments have been cut?
The femur and tibia cannot be easily separated due to the stability provided by the anterior and posterior cruciate ligaments, which prevent excessive anterior and posterior movement. Additionally, the menisci, joint capsule, and surrounding musculature contribute to maintaining the alignment and stability of the knee joint.
The femur can only be rotated in one direction in relation to the tibia. Which direction is this and why?
The femur can only be rotated laterally (externally) in relation to the tibia. This lateral rotation is facilitated by the popliteus muscle, which unlocks the knee joint from full extension, allowing it to flex.
What structure completes the superior arch of the shoulder arch of the shoulder joint in the living?
Coracoacromial ligament
