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Does fibula participate in rotational movement of ankle or not (just like the radius in forearm)? If not, what is the purpose of that bone? lower leg

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  • $\begingroup$ The Tibia is just like the Radius bone in the forearm, which combined with the biceps, enables the hand to rotate. Could there be a similarity? $\endgroup$ – user27740 Dec 2 '16 at 20:26
  • $\begingroup$ the Tibia is just like the Ulna. $\endgroup$ – Gleb Voronchikhin Dec 3 '16 at 19:54
  • $\begingroup$ @GlebVoronchikhin - The tibia is not really like the ulna. If you take a closer look at the articulation of the tibia/fibula with the talus, you'll see that the fibula allows a nice fit with stability. $\endgroup$ – anongoodnurse Dec 3 '16 at 22:57
  • $\begingroup$ @anongoodnurse so the fibula's main function is not rotation of the foot? $\endgroup$ – Gleb Voronchikhin Dec 4 '16 at 7:24
  • $\begingroup$ Two bones in lower limb (forearm or leg) is the ancestral condition for mammals. But, depending on size, there can be some degree of fusion between the two bones. Mammoth and rhino skeletons can show this. The hypothesized biomechanical trade-off is stability on uneven terrain (so, joint flexibilty is useful) vs weight support (robust limb is useful). Need to hunt down appropriate refs and skeleton images, though. $\endgroup$ – Kara Apr 6 '17 at 13:23
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It does function in the rotation and stabilization of the foot, but that is not why we have it, even species in which it serves no function still have it. A bone does not necessarily have to have a purpose in an organism, instead it can have on in its ancestors.

We have this arrangement becasue we inherited the basic limb bone arrangement from our fishy ancestors. Basically all tetrapods share the same pattern of bones in their limbs, one bone, two bones, many small bones, followed by several groups of long thing bones. this goes for front and hind limbs.
enter image description here

tetrapod evolution

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