Proko has this annoying intro music. You will be mentally damaged by it. I wish I was kidding. There are plenty of classical anatomy videos on youtube. Thing is that you have to draw everyday, hour everyday, to get got at it.
This one is a classic and is as much about artistic sensitivity as it is about the technical side about how each bone and muscle relates with the surrounding parts. It was written in the fifties, and almost everything on it was hand drawn at the time.
Loads of content and a bit of medical jargon here and there, but if you were to start studying anatomy today and could only choose one source, i’d point to this one.
the classic technique below, for example, was popularized by him
While they’re made to teach drawing, many concepts translate really well to 3d sculpting (proportions, dynamic poses, “make your drawing tell a story”, etc.
The content is in a bit of a grey area, though: he died in 59 and his last book was released in 61. They became a bit rare phisically, but the internet archive still keeps copies of the age-old versions and it wasn’t taken down even today. This made much of the content popular for drawing courses and such, even if it isn’t public domain.
Only recently (less than a decade ago) new editions were released in US (most other countries are out of luck).