(Latin, Eustachius). Born circa 1510; died August 1574. Italian anatomist and physician.

Eustachio studied in Rome. Later he was a professor of anatomy in the Sapienza in Rome. He was the papal physician in residence. Eustachio was one of the founders of scientific anatomy, which he based on the comparative-anatomical examination of human organs and the organs of human embryos and on pathologicoanatomic autopsy. In Writings on the Organ of Hearing (1563) he described the human organ of hearing in detail for the first time; he dis-covered the connecting canal between the inner ear and the nasopharyngeal cavity (the so-called eustachian, or auditory, tube) and the semilunar valve of the inferior vena cava. He studied and described the structure of other organs. He created the Tabulae anatomicae, which were published in 1714 (38 drawings). Eustachio was a follower of C. Galen and an opponent of A. Vesalius in his views.