Boyer diss 2009 1046..

on the astragalus. In anterior view the medial malleolus appears to have a “sharp” tip.
This is due to the presence of two prominent depressions on its distomedial surface.
Function.—Most features of the tibia suggest against leaping or cursorial
locomotion, including the relatively anteroposteriorly shallow tibial plateau, a concave
lateral tibial condyle, the absence of a prominent cnemial crest, a proximally situated
groove for the patellar tendon, and an ungrooved astragalar articular surface (Boyer and
Bloch, 2008).
The relative sizes of the tibial and femoral condyles have implications for
mobility at the knee (Sargis, 2002b). The ratio between the lengths of the medial femoral
and tibial condyles is 0.9 while that between the lateral condyles is 0.75. A lateral tibial
condyle that is enlarged and a corresponding lateral femoral condyle that is reduced,
compared to one another or the medial condyles, suggests that the capacity of the tibia to
axially rotate on the femur was enhanced, with the medial condyle serving as the axis of
rotation, and translation occurring between the lateral condyles. On the femur, the
relatively large pit for the popliteus tendon may indicate that this muscle had an
important role in causing or maintaining a certain degree of medial rotation. The
dramatic concavity of the posterior surface of the proximal tibial shaft may indicate a
robust tibialis posterior muscle or flexor digitorum tibialis. The former of these muscles
is a plantar flexor and invertor, while the latter is typically the most important muscle for
flexing the digits during powerful grasping in certain primates (Boyer et al., 2007). The
concavity of the lateral surface would have held part of the attachment of tibialis anterior,
a dorsiflexor and pedal invertor, but this surface is not unusual in its proportional size or
morphology. The distal end of the tibial shaft is notable in the roughened surface of the
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