(Chapter 21) Footnote 68:

In the ancient Greek authors most often cited by Vesalius, the e)pwmi/j is not the (deltoid) muscle but the point of the acromion in the region of the acromioclavicular joint (where portions of the deltoid muscle originate), e.g. in Hipp. De articulis 1.14, 10.16, 11.8-10, etc., Galen De usu partium 4.123.4, 134.9-11, 136.5, 255.16, 257.8, 304.9, 305.2-7, 309.6; in De anat. admin. the deltoid is regularly β€œthe muscle of the e)pwmi/j.” In Aristotle HA 493a9, the e)pwmi/j is the back of the neck. In the 1555 edition Vesalius adds a parenthetical concession β€œ(and likewise sometimes this process itself).”