Deviation of STJ axis etc..

Hello, As a student just getting to grips with the biomechanics side of the job I would just like to clarify if I have an understanding of how a medially/lateraly deviated STJ axis affects the muscles that control the moments about the axis. We haven’t been taught a great deal about this in uni, I was actually shown on a placement how to plot the axis by putting the foot in neutral and trying to eliminate any frontal plane motion when pressing on the heel…..Anyway the pod i was with said (although not definitively) that the muscles inserting around the axis would change functionally if the axis was medially or laterally deviated due to longer/shorter moment arms created by the deviation. For example if the axis was medially deviated then the peroneous brevis muscle would gain a greater mechanical advantage and pronate the foot further….That bit seems clear, but the functioning of tibialis posterior not acting to invert the foot??

Hello, As a student just getting to grips with the biomechanics side of the job I would just like to clarify if I have an understanding of how a medially/lateraly deviated STJ axis affects the muscles that control the moments about the axis. We haven’t been taught a great deal about this in uni, I was actually shown on a placement how to plot the axis by putting the foot in neutral and trying to eliminate any frontal plane motion when pressing on the heel…..Anyway the pod i was with said (although not definitively) that the muscles inserting around the axis would change functionally if the axis was medially or laterally deviated due to longer/shorter moment arms created by the deviation. For example if the axis was medially deviated then the peroneous brevis muscle would gain a greater mechanical advantage and pronate the foot further….That bit seems clear, but the functioning of tibialis posterior not acting to invert the foot??

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Deviation of STJ axis etc..