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.
A second pectoral muscle, the pectoralis minor, lies beneath the pectoralis major. The pectorals are predominantly used to control the movement of the arm, with the contractions of the pectoralis major pulling on the humerus to create lateral, vertical, or rotational motion.