It was always very clear to me from my basic anatomical knowledge that the "delts" are obviously divided in three section: anterior, middle and posterior.
Very easy to spot on muscular bodies with lower body fat or verifiable through palpation.
So understandably I was pretty shocked to find out that the deltoid actually has 7 (!) distinct segments ... like with all the anatomical details: tendons, insertions and function; not some weird artifact of dissecting the muscles, but real anatomic structures[0].
And thanks to super-physiological levels of steroids and testosterone it is even visually verifiable on extremely low-fat bodybuilders[1], once you know what to search for.
[0]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3042752/
[1]https://www.strengthlog.com/lateral-delts-muscles-exercises-...