Which muscle elevates ribs?

Which muscle elevates ribs?

• A. Sternocleidomastoid
• B. Sternohyoid
• C. External Intercostals
• D. Diaphragm

Answer: (C)

The muscle that elevates the ribs during inspiration is the external intercostals. These muscles run between adjacent ribs and, when they contract, they pull the ribs upward and outward. This action increases the thoracic cavity’s volume both in the front-to-back and side-to-side dimensions, helping air flow into the lungs. Their primary role is direct rib elevation, which is why they’re the best answer for elevating the ribs. Other options aren’t the main rib elevators. The sternocleidomastoid can assist with deep or labored inspiration by raising the upper chest, but it’s not a primary rib elevator. The sternohyoid hyoid-depressing muscles aren’t involved in moving the ribs. The diaphragm does not elevate ribs; it increases thoracic volume mainly by flattening to enlarge the vertical dimension of the thorax, while the external intercostals handle the direct rib elevation during breathing.

The muscle that elevates the ribs during inspiration is the external intercostals. These muscles run between adjacent ribs and, when they contract, they pull the ribs upward and outward. This action increases the thoracic cavity’s volume both in the front-to-back and side-to-side dimensions, helping air flow into the lungs. Their primary role is direct rib elevation, which is why they’re the best answer for elevating the ribs.

Other options aren’t the main rib elevators. The sternocleidomastoid can assist with deep or labored inspiration by raising the upper chest, but it’s not a primary rib elevator. The sternohyoid hyoid-depressing muscles aren’t involved in moving the ribs. The diaphragm does not elevate ribs; it increases thoracic volume mainly by flattening to enlarge the vertical dimension of the thorax, while the external intercostals handle the direct rib elevation during breathing.