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.
Movements of the scapula are brought about by the scapular muscles. 1  The scapula can perform six actions: 2  Elevation: upper trapezius and levator scapula. 3  Depression: lower trapezius. 4  Retraction (adduction): rhomboids and middle trapezius. 5  Protraction (abduction): serratus anterior. 6  Upward rotation: upper and middle trapezius.