Arches of the Foot
The arches of the foot function as shock absorbers, weight distributors, and levers for propulsion. They are maintained by the shape of the bones, strong ligaments (e.g., plantar calcaneonavicular/spring ligament), and active muscle support.
Types of Arches
- Medial Longitudinal Arch: Higher and more flexible. Composed of the calcaneus, talus, navicular, three cuneiforms, and the first three metatarsals.
- Lateral Longitudinal Arch: Lower and flatter. Composed of the calcaneus, cuboid, and the fourth and fifth metatarsals.
- Transverse Arch: Formed by the cuboid, cuneiforms, and the bases of the metatarsals.
Key Support Structures
| Structure | Role |
|---|---|
| Spring Ligament | Supports the head of the talus; essential for the medial longitudinal arch. |
| Plantar Aponeurosis | Provides passive tension to maintain arch integrity. |
| Tibialis Posterior | Active muscle support; pulls the navicular and medial cuneiform superiorly. |
High-Yield Exam Pearl:
Pes planus (flat foot) is frequently caused by dysfunction or insufficiency of the tibialis posterior tendon. This failure leads to collapse of the medial longitudinal arch and a characteristic “too many toes” sign when viewed from behind.