Julius Caesar Aranzi (Giulio Cesare Aranzio, Arantius) (1529/1530 – April 7, 1589) was a leading figure in the history of the science of human anatomy.
Owing to the poverty of the family, he studied with his uncle Bartolomeo Maggi (1477–1552), a famous surgeon who was a lecturer at the University of Bologna as well as court physician to Julius III.
From Aranzio came the first correct account of the anatomical peculiarities of the fetus, and he was the first to show that the muscles of the eye do not, as was previously imagined, arise from the dura mater but from the margin of the optic hole.
Aranzio was the first anatomist to describe distinctly the inferior cornua of the ventricles of the cerebrum, who recognizes the objects by which they are distinguished, and who gives them the name by which they are still known (hippocampus) in 1564; and his account is more minute and perspicuous than that of the authors of the subsequent century.
His books (in Latin) covered surgical techniques for many conditions, including hydrocephalus, nasal polyp, goitre and tumours to phimosis, ascites, haemorrhoids, anal abscess and fistulae.