Anatomy is the branch of biology concerned with the study of the structure of organisms and their parts; with further division into zootomy and phytotomy. Anatomy is related to embryology and comparative anatomy, which itself is closely related to evolutionary biology and phylogeny. Human anatomy is one of the basic essential sciences of medicine. The discipline of anatomy is divided into macroscopic and microscopic anatomy. The history of anatomy is characterized by a progressive understanding of the functions of the organs and structures of the human body.