Question

during volume changes in the thoracic cavity, what is primarily responsible for changes in length?
multiple choice
the abdominal muscles
the diaphragm
the ribs and sternum
the intercostal muscles

Explanation:

The diaphragm is a dome - shaped muscle that separates the thoracic cavity from the abdominal cavity. When it contracts, it flattens, increasing the vertical (length) dimension of the thoracic cavity. The abdominal muscles are more involved in forced exhalation and core stability. The ribs and sternum, along with the intercostal muscles, are mainly responsible for the transverse (width) changes in the thoracic cavity. The intercostal muscles (external and internal) help in the movement of the ribs during breathing but do not primarily change the length of the thoracic cavity.

Answer:

The diaphragm