Which muscles do pull-ups work?

Being able to do a pull-up is a common fitness goal but which muscles do pull-ups work and why are they so difficult?

What muscles do pull-ups work? And how to use a pull-up bar - The Mail

Pull Ups Muscles Worked - Looking at Muscle Activation In Depth

What Muscles Do Hammer Grip Pull Ups Work? The Complete Guide – DMoose

Muscle-up - Wikipedia

Which muscles group does pull ups grow? - Quora

What groups of muscles does a reverse grip pull up work? - Quora

What Muscles Do Pull Ups Work & Benefits – Intent Sports

What Muscles Do Pull-Ups Work?

What Muscles Do Pull Ups Work?

Which muscles do pull-ups work?

How To Do Pull-Ups For A Bigger And Shredded Back