Muscle of expiration
a. During expiration, the diaphragm simply relaxes, and the elastic recoil of the lungs, chest wall, and abdominal structures compresses the lungs.
b. During heavy breathing → Expiration →extra force is achieved mainly by contraction of the abdominal muscles
c. Muscles that pull the rib cage down ward are classified as muscle of expiration: - are
i. Abdominal recti →powerful effect
ii. Internal intercostals muscles.
a. Contraction of Diaphragm is a most important in inspiration.
b. Muscle that elevate the chest cage are classified as Muscles of inspiration:- are
i. External intercostals→ most important muscles that raise the rib cage
ii. Sternocleidomastoid, Anterior serrati, and scaleni~ that help in the raising the ribs cage.