Question

For the atmospheric air to go into our body, a low pressure is created when the internal intercostal muscles ______ and external intercostal muscles______ .

• A. Relax, contract
• B. Contract, relax
• C. Contract, contract
• D. Relax, relax

Answer 1

The correct option is A Relax, contract

The intercostal muscles are located in between the ribs and facilitate breathing. There are two types of intercostal muscles - internal intercostal muscles and external intercostal muscles. The internal intercostal muscles relax and external intercostal muscles contract during inhalation. This action combined with that of diaphragm and rib cage decreases the pressure in the thoracic cavity by increasing the volume, allowing atmospheric air to flow inside.