Our decision to dedicate several years to the writing of this Atlas was based on the professional acknowledgement of negative surgical results due to incorrect or incomplete approaches to the bones or joints requiring treatment. We are convinced that in order to obtain the best possible anatomic and functional results in surgery of the locomotor apparatus, it is necessary to obey several rules of behaviour con- stituting the basis for correct surgical execution: a) to respect the anatomy of the muscular and neural formations; b) to safeguard the vascularization of these anatomical elements and consequently of the osteoarticular apparatus; c) to use the most appropriate surgical approaches fully respecting the regional anatomy and the least traumatic exposure of the skeleton; d) to correctly perform surgery, thus creating the best conditions for the excel- lent recovery of the function of the limb. The anatomic findings and surgical approaches to the extremities described here are not complete: we have based our selection of the former on their frequency in the normal surgical activity of any specialised ward, and the latter on the surgi- cal approaches most commonly used by the 3rd Division of the Rizzoli Orthopaedic Institute. Wide surgical approaches for the surgical treatment of bone tumors have been excluded as they deal with specific "compartmental" methods which do not involve the anatomic rules to be followed in the normal treatment of orthopaedic and trau- matologic affections of the extremities.