Contraction of which muscle normally accounts for around 75% of the air movement in normal quiet breathing?
A) diaphragm
B) rectus abdominis
C) internal intercostals
D) external intercostals
E) internal obliques

Question

Quizplus · Accepted Answer

The diaphragm is the main muscle responsible for the majority of air movement in normal quiet breathing. It contracts and flattens during inhalation, increasing the volume of the thoracic cavity and creating a negative pressure gradient that allows air to flow into the lungs. The other muscles listed also play a role in breathing, but to a lesser extent.

Contraction of Which Muscle Normally Accounts for Around 75% of the Air