Correlation between the Morphology of the Feet and Muscle Fiber Composition in the Anterior Tibial Muscle

Functional differences among the shapes of the feet in mammals, i.e. plantigrade, digitigrade and unguligrade types, were investigated in terms of muscle fiber composition, in specimens of the anterior tibial muscle, obtained from 17 species of mammals. The number of muscle fibers per unit area was the largest in the digitigrade type (on the order of 990 cells), followed by the unguligrade type (on the order of 750 cells) and was the smallest in the plantigrade type (on the order of 540 cells). With respect to the muscle fiber type, red muscle fibers for slow contraction were most frequently seen in the unguligrade type, white muscle for fast contraction in the plantigrade type and intermediate muscle fiber for plastic contraction in the digitigrade type.