The sternal part lowers the costal cartilages, facilitating inhalation by increasing the upper body cavity.???? ?? ???? ???? ??? ?? ?????? ?????? ?? ????? ???? ?? ??? ???? ?? ????? ???? ???? ??? ?? ?? ?????? ???? ???? ?? ????? ???? ???? ??.The diaphragm is really a dome-shaped muscular partition that is found at The bottom of your thoracic cavity.