Anatomy is the scientific study of the structures of the body. All physicians must master anatomy in medical school. It started to develop as a science during the Renaissance, when several scholars, including Leonardo da Vinci, started dissecting corpses to study muscle structure in living bodies. The subsequent development of anatomy as a science is what eventually allowed western style medicine to surpass both Arabic and eastern traditions of medicine, which did not develop past the stage of studying superficial anatomical features.
Gray's Anatomy, which was first published in 1858 and has been continuously updated since, is considered to be the definitive work on human anatomy.