Which muscles are located between the ribs and assist in breathing?

Which muscles are located between the ribs and assist in breathing?

• A. Abdominals
• B. Intercostal muscles
• C. Pectoralis major
• D. Serratus anterior

Answer: (B)

The muscles between the ribs are responsible for changing the size of the thoracic cavity to allow air to move in and out. These intercostal muscles include the external intercostals, which lift the ribs during inspiration to expand the chest, and the internal intercostals (aided during forced expiration) that help depress the ribs to reduce chest volume. While the diaphragm does most of the work in quiet breathing, the intercostals provide the necessary rib cage movement to increase or decrease thoracic volume and thus drive ventilation. Other muscles listed aren’t located between the ribs. Abdominals sit in the abdomen and mainly help force expiration by pushing the diaphragm upward; pectoralis major and serratus anterior are chest wall muscles that can assist with breathing in certain deep or resisted efforts, but they aren’t the muscles directly between the ribs.

The muscles between the ribs are responsible for changing the size of the thoracic cavity to allow air to move in and out. These intercostal muscles include the external intercostals, which lift the ribs during inspiration to expand the chest, and the internal intercostals (aided during forced expiration) that help depress the ribs to reduce chest volume. While the diaphragm does most of the work in quiet breathing, the intercostals provide the necessary rib cage movement to increase or decrease thoracic volume and thus drive ventilation.

Other muscles listed aren’t located between the ribs. Abdominals sit in the abdomen and mainly help force expiration by pushing the diaphragm upward; pectoralis major and serratus anterior are chest wall muscles that can assist with breathing in certain deep or resisted efforts, but they aren’t the muscles directly between the ribs.