Question

Mark the correct pair of muscles involved in the normal breathing in humans.
a. External and internal intercostal muscles
b. Diaphragm and abdominal muscles
c. Diaphragm and external intercostal muscles
d. Diaphragm and intercostal muscles

Answer 1

Hint: The process of moving air in and out of the lungs of the body is called breathing. Human beings inhale oxygen and exhale carbon dioxide during the breathing process. The chest cavity size will increase while inhalation and decrease while exhalation.

Complete answer:
There are two stages which are involved in the breathing process:
- Inspiration in which atmospheric air is taken in.
- Expiration in which alveolar air is released.

The pressure within the lungs is less than the atmospheric pressure then inspiration takes place and the pressure is called intrapulmonary pressure. This pressure is also referred to as negative pressure in the lungs. The intramolecular pressure if higher than the atmospheric pressure then expiration takes place. The generation of various gradients between the ribs is done by the diaphragm and specialized set of muscles external and internal intercostal.

The ribs extend from the front and go around the back, bend in the ribs is called internal intercostal muscles whereas the ribs that wrap around the back of the rib almost to the bony end part in the front are called external intercostal muscles.

The intra-abdominal pressure controls the diaphragm by contraction with the abdominal muscles during the process of breathing. The muscles which are situated between the ribs and the pelvis on the front of the body is called abdominal muscles.

Hence, the correct answer is option (D).

Note: As we know that till now diaphragm is the part of the lungs that helps in the breathing process in humans. It creates the pressure during inspiration and expiration of oxygen and carbon dioxide. The internal intercostal muscles and diaphragm are the components that generate pressure. All the different processes during breathing take place in the lungs.