Gas expands, volume increases (surface area increases) as P = F/A. Clearly force also needs to increase to keep P constant. A greater force means a greater rate of change of momentum, so the molecules must have a greater mean kinetic energy. Therefore the gas must be at a higher temperature meaning heat energy (Q) must be supplied.
When the shoulder is shrugged, this muscle is at work. When a heavy bag is carried, the levator scapulae muscle helps the body bear the burden. This muscle begins at the vertebrae just below the skull, called the cervical vertebrae. It is attached to the transverse processes of the cervical vertebrae.
This side of the scapula is relatively unremarkable, with a concave depression over most of its surface, called the subscapular fossa. The subscapularis muscle, one of the rotator cuff muscles, originates from this side. Originating from the superolateral surface of the costal scapula is the coracoid process.