Foot
Foot Movement
Active movements of the foot is limited to the movements associated with the toes. The arches of the foot allow the foot to efficiently support the weight of the body while simultaneously allowing flexibility for movement and balance. The space created underneath the arch allows for the passage of muscles, tendons, and ligaments which act as springs that provide shock absorption and store energy to be returned during movement. The arches are formed by the position and shape of the foot bones, and strengthened by tendons and ligaments. There are two distinct longitudinal arches in the foot that run from front to back: the medial (inside) arch and the lateral (outside) arch.
Muscles
Medial Arch
Its weakest part (i.e., the part most liable to yield from overpressure) is the joint
between the talus and navicular, but this portion is braced by the plantar
calcaneonavicular ligament, a.k.a. spring ligament, which is elastic and is thus able to quickly restore the
arch to its original condition when the disturbing force is removed. The ligament is strengthened medially by blending with the deltoid
ligament of the ankle joint, and is supported inferiorly by the tendon of the Tibialis
posterior, which is spread out in a fanshaped insertion and prevents undue
tension of the ligament or such an amount of stretching as would permanently
elongate it. The arch is further supported by the plantar
aponeurosis, by the small muscles in the sole of the foot, by the tendons of
the Tibialis anterior and posterior and Peronæus longus,
and by the ligaments of all the articulations involved.
Lateral Arch
The lateral arch is composed of the calcaneus, the cuboid, and the fourth and fifth metatarsals. Two notable features of this arch are its solidity and its slight elevation. Two strong ligaments, the long plantar and the plantar calcaneocuboid, together with the Extensor tendons and the short muscles of the little toe, preserve its integrity.
Evaluating movement dysfunction
Posture evaluation
Look for low arch (flat foot). Is often associated with foot inversion (pronation). Flat feet (also called pes planus or fallen arches) is a postural deformity in which the arches of the footcollapse, with the entire sole of the foot coming into complete or near-complete contact with the ground.