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If you look at the illustration on the right, you will notice two 'twisting' ligament that inserts from the center of the thigh bone to the middle of the shin bone. The Anterior Cruciate Ligament (ACL) is the one in the front. Because of its location, it resists Anterior Translation (also shown in the illustration). The second 'twisting' ligament on the back is the Posterior Cruciate Ligament (PCL), which resists Posterior Translation of the joint.

I apologize for not being clear. I hope this explanation helped.

Thanks for getting through the post, I know it was a bit long. I hope you found it interesting though.

Damned it was on the picture and I missed it! I will hide in shame now. Thanks for having taken the time to answer, even if this was a stupid question.

Nothing to worry about. I should have explained things in both the text as well as the illustrations. I get so used to using the anatomical language, I forget that not everyone is fluent in it. I will expand all the abbreviations in the next post.

I will expand all the abbreviations in the next post.

Yep this is a good practice (to be used everywhere, btw :p)