The fasciae of the foot

The fascia of the leg passes directly into the fasciae of the foot. On the dorsum of the foot, the superficial plate of the dorsal fascia of the foot (fascia dorsalis pedis) is poorly developed. The deep plate of the dorsal fascia of the foot (interosseous fascia), covering the dorsal interosseous muscles, tightly fuses with the periosteum of the metatarsal bones. Between both plates of the dorsal fascia of the foot are the tendons of the anterior tibialis muscle, the long and short extensors of the toes with their synovial sheaths, blood vessels and nerves.

On the sole of the foot, the thick skin is connected by connective tissue bridges to the plantar aponeurosis, which is part of the proper fascia of the sole of the foot. Directly under the skin of the sole of the foot is a thick superficial fascia called the plantar aponeurosis (aponeurosis plantaris) and is tightly fused along almost its entire length with the lower surface of the short flexor of the fingers, which begins from the calcaneus. At the level of the metatarsal bones, the plantar aponeurosis expands, thins and divides into 4-5 flat bundles that are directed toward the toes and are woven into the walls of their fibrous sheaths. The longitudinal bundles of the aponeurosis at the level of the heads of the metatarsal bones are reinforced by transverse bundles that form the superficial transverse ligament of the metatarsus. From the upper surface of the aponeurosis facing the muscles of the sole in the sagittal plane, two intermuscular septa extend, separating the middle group of muscles from the medial and lateral.

The medial intermuscular septum (of the sole) fuses with the periosteum of the calcaneus, navicular, medial cuneiform, and first metatarsal bones. The lateral intermuscular septum attaches to the fibrous-osseous canal of the peroneus longus tendon and to the periosteum of the fifth metatarsal bone.

The medial compartment contains two muscles: the abductor hallucis and the short flexor hallucis, as well as the tendon of the long flexor hallucis. Between the calcaneus (laterally) and the abductor hallucis muscle (medially), there is a 3-3.5 cm long calcaneal canal, through which the medial vascular-nerve bundle (medial plantar artery, veins, and nerve) passes.

The middle fascial bed is divided by the deep fascia plate into two parts: the deep (upper) part, in which the interosseous muscles are located, and the superficial (lower) part, in which there are two layers of muscles. In the first layer (lower) are the short flexor of the toes and the quadratus plantaris muscle. Above them, in the second (upper) layer, are the tendons of the long flexor of the toes, the lumbrical muscles, the muscle that adducts the big toe, as well as the tendon of the long peroneus muscle, surrounded by its own synovial sheath.

In the lateral fascial compartment are the abductor digiti minimi muscle and the flexor digiti minimi brevis muscle.

At the level of the fingers, from the line of the metacarpophalangeal joints to the base of the distal (nail) phalanges, the tendons of the long and short flexors of the fingers (IV) are surrounded (each in its own bone-fibrous canal) by the synovial sheaths of the tendons of the toes (vaginae tendinum digitorum pedis).

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