Sycra Yasin is a literal godsend to this earth and I love him to death. If you want comprehensive muscle tutorials, THIS GUY is YOUR GUY.
Second, let me introduce you to George Bridgman:
Studying this kind of structural anatomy is super helpful for learning and simplifying any kind of figure.
I’ve compiled some hand/arm tutorials from both myself and mod goji for some further study:
As for posing the arm with the body, I like to use this simplified form of the arm to create my sketch poses so I know what the overall will look like.
It’s not a direct science, and it is a lot of muscle memory. Knowing how long the arms should be in conjunction with the torso is still a struggle for me. When in doubt, do the pose yourself! See how you look in a mirror 🙂
Wanted to draw Ishida from chapter 33, and also need to give props to the wonderful @2ki8h1 because how they drew Ishida with fluffy hair just made me wanna draw him even more.