Topographic anatomy. Leonardo began the formal study of the topographical anatomy of the human body when apprenticed to Andrea del Verrocchio.As a student he would have been taught to draw the human body from life, to memorize the muscles, tendons and visible subcutaneous structure and to familiarise himself with the mechanics of the various parts of the skeletal and muscular structure.
Leonardo used light brush strokes and no lead. When the Annunciation was x-rayed, Verrocchio's work was evident while Leonardo's angel was invisible. The product of collaborative efforts in Verrocchiio's studio, this picture is nonetheless a masterful achievement and proof of Leonardo da Vinci's innate pictorial talent.