[Normal and abnormal imaging of the foot's extensor system].

The extensor system of the foot is mainly composed by a powerful engine, the triceps surae muscle, equiped with a very sophisticated driving belt, the unit Achilles tendon-posterior part of calcaneus bone-plantar aponeurosis, in continuity with the fibrous skeleton of the triceps surae. The exact knowledge of the anatomy of this fibrous skeleton allows us to understand the occurence of the main anatomical lesions of the extensor system and its imaging. On these solid bases, it's possible to divide the lesions of the foot's extensor system in different subtypes with, for each one, a typical clinical feature, a characteristic imaging and an codified treatment. The pair radiography-ultrasonography is enough for diagnosis and follow-up of the majority of lesions. The others need MRI.