Can you get your arms overhead? Move the sliders and see where it comes from

Raising your arm overhead is three movements at once: the upper arm turns in its socket, the shoulder blade rotates upward, and the upper back straightens a little.

Move the sliders on a simple side-view model to see how each part adds up to a full reach, and how arching the lower back can make a stuck shoulder look fine. Then try a quick wall check and learn what gentle practice helps, and when to see a doctor or physio.