Shoulder Blade Alignment

If I stand next to a wall with my arms straight down by my side I can feel my right shoulder blade poking into the wall. From brief research the area of the scapula sticking out is the inferior angle. If I lift my arms up I cant feel it anymore. This can be annoying sitting in a chair or lying on my back. I was wondering what muscles are particularly weak and need stregthening?

All my research leads to a Winged Scapula but the definitions I find are "A winged scapula is a shoulder injury or condition in which the scapula or shoulder blade sticks out at the back, particular when pushing". Yet mine seems fine while pushing only during rest.

It has come to my attention due to an attempt to improve my posture.

The medial border of the scapula is help down by the serratus anterior muscle. Trauma to neural structure can cause dysfunction in that muscle leading to a winging of the scapula. That said many people with slight physiques have winging scapulae at rest. This does not mean they are dysfunctional and indeed yours seems normal as it does not wing when you perform a press movement. In injury or dysfunction to the mm group would still exhibit winging during a pressing activity e.g. push-ups. Usually a trauma would result in only one side winging whilst a system disease process would show winging in both.

There are many exercises that can build muscle in that area, the push-up being one of them. It's best to consult someone directly for that.