Question

During inspiration muscles of diaphragm

• A. Contracts
• B. Expands
• C. No effect
• D. Coiled like string

Answer 1

Answer: (A)

Contracts

During inhalation, the diaphragm contracts, thus enlarging the thoracic cavity. This reduces intra-thoracic pressure: enlarging the cavity creates suction that draws air into the lungs. When the diaphragm relaxes, air is exhaled by elastic recoil of the lung and the tissues lining the thoracic cavity in conjunction with the abdominal muscles, which act as an antagonist, paired with the diaphragm's contraction.

Hence the correct option is A.