Which muscle acts as the primary inverter of the foot, with assistance from tibialis anterior?

Which muscle acts as the primary inverter of the foot, with assistance from tibialis anterior?

• A. Tibialis anterior
• B. Tibialis posterior
• C. Fibularis longus
• D. Flexor digitorum longus

Answer: (B)

Inversion of the foot is produced mainly by a muscle whose tendon runs along the inside of the leg and inserts near the arch of the foot. The tibialis posterior does exactly that: its tendon passes behind the medial malleolus and pulls the midfoot bones medially and upward, making it the most effective inverter. It also helps support the medial longitudinal arch, which is crucial for stability during standing and walking. The tibialis anterior can assist with inversion, especially when the foot is dorsiflexed, but its primary job is to dorsiflex the foot rather than invert it. The fibularis longus on the outside of the leg tends to evert the foot, not invert it, and the flexor digitorum longus mainly flexes the toes (while contributing to plantarflexion and some arch support). So the main inverter is tibialis posterior, with assistance from tibialis anterior.

Inversion of the foot is produced mainly by a muscle whose tendon runs along the inside of the leg and inserts near the arch of the foot. The tibialis posterior does exactly that: its tendon passes behind the medial malleolus and pulls the midfoot bones medially and upward, making it the most effective inverter. It also helps support the medial longitudinal arch, which is crucial for stability during standing and walking. The tibialis anterior can assist with inversion, especially when the foot is dorsiflexed, but its primary job is to dorsiflex the foot rather than invert it. The fibularis longus on the outside of the leg tends to evert the foot, not invert it, and the flexor digitorum longus mainly flexes the toes (while contributing to plantarflexion and some arch support). So the main inverter is tibialis posterior, with assistance from tibialis anterior.