Physiologically breathing is of 2 types: Abdomino-thoracicand thoraco-abdominal. Females have thoraco-abdominal breathing while males have abdomino-thoracic breathing. There is 2 reason for thoraco-abdominal breathing in female first is that females have a greater inclination of ribcage than males. This causes the intercostal muscles to raise the ribs more effectively so increasethe action of intercostal muscles accounts for more prominent thoracic breathing also due to greater inclination of rib cage females have lesser thoracic dimension. But why do females have more inclined rib cage? Unlike males where the rib cage plays a role to accommodate lung volume displacement only. In females, the rib cage serves to do all purposes to accommodate both lung volume as well as abdominal volume displacement. This abdominal volume displacement is a functional adaptation to pregnancy, it minimizes the distending effect of the pregnant uterus on the lung and also decreases abdominal pressure. The second reason is that diaphragm length is 9% shorter in females than in males. So what about the males, who have more horizontally oriented rib cage. Abdomino-thoracic breathing is seen in males because breathing in them is chiefly by their long diaphragm which is 9% greater than females. The males have more horizontally oriented rib cage. So there is inefficient action of intercostal muscle, making thoracic breathing less prominent in them. During inspiration, the diaphragm descends that pushes the abdominal viscera down and, therefore, the abdominal wall is raised. Thus abdominal movement becomes prominent and contraction of abdominal muscles facilitates breathing. Diaphragmatic breathing could be a compensationfor inefficient action of intercostal muscles in males. The greater diaphragmatic action in males is linked to male thoracic morphology which is wider at the corner part, greater medial-lateral expansion of lower lungs, and more pyramidal shape of the male lung.