Muscles of expiration (mahe 98)

Muscles of expiration - (MAHE 98)


a. Diaphragm


b. Internal intercostal


c. External intercostal


d. Rectus Abdominis





(b) Internal intercostals
(d) Rectus Abdominis


Ref: Ganong 653
♦ A decrease in intrathoracic volume and forced expiration result
when the expiratory muscles contract
♦ The internal intercostals have this action because they pass
obliquely downward and posteriorly from rib to rib and therefore
pull the rib cage downward when they contract
♦ Contractions of the muscles of the anterior abdominal wall also
aid expiration by pulling the rib cage downwards and inward & by
increasing the intra-abdominal pressure, which pushes the
diaphragm upward