The Overhead Extension exercise works your shoulders and triceps.
This exercise works your tricep, the muscle down the back of your arm that extends your elbows. Your pitch slightly forward with your torso that your bend makes a diagonal from your hands down to the door. As you work here, you wanna make sure that your shoulders stay plugged down your back and that your elbows stay still. You should also feel a lot of added benefit for your core if you're working those arms with enough resistance overhead.