As the thoracic muscles relax, what happens to the volume of the thoracic cavity?

1 Answer
Nov 13, 2016

Comes to its normal position

Explanation:

As the thoracic muscles relax thoracic volume comes to its normal position.http://archive.cnx.org/contents/b166b84c-33fa-40cb-8d2b-0566172d5caf@1/the-process-of-breathing

During inspiration

  • Diaphragm contracts leading to increase in volume of thoracic chamber in the antero-posterior axis
  • Contraction of external inter-costal muscles lifts up the ribs and sternum causing an increase in the volume of the thoracic chamber in the dorso-ventral axis
  • Hence there is an increase in pulmonary volume

During expiration

  • Relaxation of Diaphragm and external inter-costal muscles returns the diaphragm and sternum to their normal positions and reduces the pulmonary volume.