Question

Contraction of diaphragm during inhalation

• A. It decreases the volume of the thoracic chamber in the anteroposterior axis.
• B. It increases the volume of the thoracic chamber in the dorso-ventral axis.
• C. It increases the volume of the thoracic chamber in the anteroposterior axis.
• D. It decreases the volume of the thoracic chamber in the dorso-ventral axis.

Answer 1

Answer: (C)

Inspiration is initiated by the contraction of diaphragm which increases the volume of the thoracic chamber in the anteroposterior axis. 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.