The most important and detailed anatomical work of Galen, based on dissections he himself performed on the bodies of monkeys. The first book provides some general information about anatomy and the way the work is written. It also examines the anatomy of the muscles of the hand. In the second book, the anatomy of the muscles of the leg is examined, while in the third book, the anatomy of the nerves, veins, and arteries of the hand and leg is examined.