WAEC - Biology (2001 - No. 21)
The effect of the contraction of the muscles of the diaphram is that
he volume of the thoracic cavity increases.
more carbon dioxide is expelled through the nostrils
the rib cage is drawn inwards
the intercostal muscle becomes relaxed
Uitleg
The diaphragm is the main inspiratory muscle, during inspiration(air intake) it contracts and moves in an inferior direction that increases the vertical diameter of the thoracic cavity and produces lung expansion, in turn, the air is drawn in.