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Multiple Choice
Which of the following muscles are primarily responsible for normal resting state (quiet) breathing?
A
Scalene muscles
B
External intercostal muscles
C
Diaphragm
D
Sternocleidomastoid
Verified step by step guidance
1
Understand the process of normal resting state (quiet) breathing, which primarily involves the movement of the diaphragm and intercostal muscles.
Recognize that the diaphragm is the main muscle responsible for quiet breathing. It contracts and moves downward, increasing the volume of the thoracic cavity and allowing air to flow into the lungs.
Identify the role of the external intercostal muscles, which assist in elevating the ribs and expanding the chest cavity during inspiration, but are not the primary muscles for quiet breathing.
Note that the scalene muscles and sternocleidomastoid are accessory muscles of respiration, typically engaged during deep or labored breathing, not during quiet breathing.
Conclude that the diaphragm is the primary muscle responsible for normal resting state breathing, as it is the most efficient muscle for this process.