ACL/PCL attachment

[shigella123]

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I need help with this question. It always confuses me. Why is the answer D?

Here's the original question with answer:



I chose B. Here's what I was thinking: If it's right knee then Fibula would be laterally and Tibia would be medially and so ACL is on top of Fibula and PCL would be on top of Tibia and so the attachment site would be B for PCL:

 

[MrWhatupDoc]

At the tibia. PCL attaches directly posteriorly and ACL attaches directly anteriorly. They cross coming up to the femur.

 

[MrWhatupDoc]

So PCL would run from D to B if B was at the level of the femur and ACL would run from A to E if E was at the level of the femur

 

[thehundredthone]

I chose B. Here's what I was thinking: If it's right knee then Fibula would be laterally and Tibia would be medially and so ACL is on top of Fibula and PCL would be on top of Tibia and so the attachment site would be B for PCL

The ACL and PCL don't cross each other in the axial plane. The ACL is on top of the fibula only in the sense that it attaches to the later femoral condyle, and the PCL to the medial condyle. So even if you say that the PCL is above the tibia then B would be the wrong point, being more lateral.

At the tibia. PCL attaches directly posteriorly and ACL attaches directly anteriorly. They cross coming up to the femur.

Exactly. The level of the MRI is important.

Here's a diagram:

 

[shigella123]

Great, it makes sense now. This pic also helped me see why I was wrong.