When I went to college, there were 2 teachers charged with teaching anatomy to freshmen, and they had very different schools of thought about it. One teacher had a textbook approach to making students memorize body parts. I'm glad I had Mr. Larrabee instead. We drew from models, then located the bones and muscles in our drawings. I found this extremely helpful because prior to this I had only thought about the outside skin of the people I drew. This technique did a lot to flatten my ego about how well I thought I could draw at that time, but it also made me a much better artist.
Anatomy class gave me heart palpitations at first. I stopped in my tracks and did the "uh, uh, uh" the first time I saw a naked woman smoking outside of class. My suburban/rural upbringing must've been obvious because she rather casually put on her robe while I tried to scrape my jaw off the ground. She didn't bother to tie it though. My 17-year-old self will never forget her sagging breasts, stretch marks, and C-section scar. At that age I didn't really understand gravity, and I'm pretty sure the stretch marks and scar promoted my feelings about proper use of contraceptives. Later on, I laughed when I saw new crops of freshmen staggering in shock of their first naked models. I wonder if teachers ever get tired of seeing freshmen at their first anatomy class?
I think a lot of people never get to live that memorable moment or learn basic anatomy. Here are some basic rules to live by, and I think they apply no matter what style an artist is working in...
1. Arms and legs have straight bones inside of them. Okay, if you really want to get into it, there's 2 major bones in the forearm, and 2 in the calf, but let's stick with the basic principle. If you're trying to draw something that looks vaguely human, you should be able to draw straight lines from shoulder to elbow, elbow to wrist, hip to knee, and knee to ankle. In other words, avoid breaking bones in your subjects.
2. We've gotten used to distortions in photos, but viewers are less forgiving when they look at art. If a leg looks small in a reference photo, does it look like a deformity in your drawing? If you're going to make a hand huge, do it on purpose because it's aimed at the viewer. In general, body parts should look like they belong on the same body.
3. Avoid cutting off hands, feet, arms, and legs with the edge of the picture. Doing so makes your subject look like they've had an amputation. It makes people uncomfortable, even if that discomfort is on a subliminal level. Especially avoid blunt crops at joints, and show both arms and/or legs when it makes sense to show them. Otherwise the absence of a limb can also look like an amputation.
4. Muscles are convex, meaning they bulge out. They never curve in. Think of a bicep. Every muscle acts the same way, just on a lesser scale. And remember, the muscles attach to the bones inside. Imagine beginning and ending points for those muscles.
5. Practice makes perfect. Find people and pictures to study. Get an anatomy book for artists, but avoid fashion photography. That has been highly distorted in PhotoShop.
Rules were made to be broken, but if you break the rules, know what you're breaking and why. 5 rules seemed like enough for this posting, but I'd be happy to hear any other suggestions people have.
And how this ties to "acrobat"? Because basic anatomy is essential to trapeze artists, sports figures, and dodging whatever is coming your way. Both pictures are from college days. The painting is oil on canvas.