Ankle and Foot: Frontal-Plane Muscle Function

0%

Heel strike

0% · Heel strike

Tibialis posterior (deep, dashed)
Controls pronationTibialis anterior
Lowers the forefoot
Net internal torque≈ 0Right leg · highlights show activity windows, not EMG or contraction type
Schematic muscle activity (relative scale)

Tibialis posterior, fibularis group and tibialis anterior; schematic activation

+ Increasing activity− Not plotted

Schematic relative amplitude; not measured values.

Schematic muscle activity00%20%40%60%80%100%
Gait cycle: 0%

Heel strikeControl pronation • Accept body weight

Graph explanations and references

— Tibialis posterior — Fibularis longus & brevis — Tibialis anterior
Timing windows from the text; heights separate the lines and are not measured EMG.

Net joint values — do not identify which muscle is active

Combined ankle-and-foot values: approximate readings of Fig. 15.43, course textbook, ch. 15 (full citation pending), data attributed there to Winter et al. (1996). Not individual-muscle activity; small and variable between individuals. The foot is not moved by the torque.

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Chapters
Learning objectives

Read early eversion, midstance inversion and pre-toe-off eversion torque, and the ~50% energy absorption, as combined ankle-and-foot effects.

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