In many countries, PAP machines are only available by prescription. A sleep study at an accredited sleep lab is usually necessary before treatment can start. This is because the pressure settings on the PAP machine must be tailored to a patient's treatment needs.
The pectoralis major muscle also performs internal rotation -- turning your arm in toward your body. This action, also called medial rotation, is important for reaching behind your back to tuck in your shirt and combing your hair on the opposite side of your head.
Upper Versus Lower Pecs. The upper and lower pecs are simply different sides of the same muscle. The pectoralis major muscle is a wide, fan-like muscle that covers the upper rib cage and lung area. What is commonly understood as the lower pecs is the lower part of the pectoralis major. The pectoralis minor, while hidden beneath the major muscle, tightens the chest by supporting and firming the lower pecs.