Handstand question

Which are the muscles that are mostly worked when simply holding a handstand for as much as you can, with or without a wall?

Delts/Traps. However, it's a movement that works everything so it can be different weaknesses for some people.

These are all the muscles

The table is taken from The Handstand: a four stage training model by Valentin Uzunov and just edited all muscle names with links from wikipedia.

Thanks a lot you both.