alleryStart learning →In which direction does the diaphragm move when it contracts?
AInferiorly, toward the abdominal cavity
BSuperiorly, toward the thoracic cavity
CLaterally, toward the costal surfaces
DAnteriorly, toward the sternal border
Answer & Solution
Correct answer: A. Inferiorly, toward the abdominal cavity
1. The diaphragm is a dome-shaped muscle at the base of the thoracic cavity.
2. Contraction flattens the dome and moves it inferiorly, toward the abdominal cavity.
3. That creates a larger thoracic cavity and more space for the lungs.
4. Moving superiorly would shrink the thorax, so the second option would produce expiration rather than inspiration.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 22 "The Respiratory System", section 22.3 The Process of Breathing_
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