Orangutans, together with chimpanzees and gorillas, are our closest living relatives. Photographic and Descriptive Musculoskeletal Atlas of Orangutans, the first photographic and descriptive musculoskeletal atlas of the genus Pongo, adopts the same format as the photographic atlases of Gorilla, Pan and Hylobates previously published by the same authors. These four books are part of a series of monographs that will set out the comparative and phylogenetic context of the gross anatomy and evolutionary history of the soft tissue morphology of modern humans and their closest relatives. The present atlas, which includes detailed high-quality photographs of musculoskeletal structures from most anatomical regions of the body as well as textual information about the attachments, innervation, function and weight of the respective muscles, is based on dissections of five orangutans and on an extensive review of the literature. It provides an updated review of the anatomical variations within orangutans as well as an extensive list of the synonyms used in the literature to designate the structures we discuss. It will be of interest to students, teachers and researchers studying primatology, comparative anatomy, functional morphology, zoology, and physical anthropology and to medical students, doctors and researchers who are curious about the origin, evolution, homology and variations of the musculoskeletal structures of modern humans.