What is the relationship between the contraction of external intercostal muscles and the volume of the…

What is the relationship between the contraction of external intercostal muscles and the volume of the thoracic chamber?
  1. The contraction of external intercostal muscles decreases the volume of the thoracic chamber
  2. The contraction of external intercostal muscles has no effect on the volume of the thoracic chamber
  3. The contraction of external intercostal muscles increases the volume of the thoracic chamber
  4. The contraction of external intercostal muscles increases the pressure of the thoracic chamber

Solution

The contraction of external intercostal muscles lifts up the ribs and the sternum, causing an increase in the volume of the thoracic chamber in the dorso-ventral axis.

Asked in: NCERT

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