Which list is described as the bones of the respiratory pump?

Which list is described as the bones of the respiratory pump?

• A. sternum, ribs, vertebrae
• B. diaphragm, external intercostals, scalenes, sternocleidomastoid, pectoralis major
• C. internal intercostals, abdominals
• D. front of body

Answer: (B)

The respiratory pump works by muscles that move the rib cage and sternum to enlarge the chest cavity for inhalation. The diaphragm contracts and moves downward, increasing vertical space. The external intercostals lift the ribs, widening the thorax. Accessory inspiratory muscles—scalenes lift the top ribs, sternocleidomastoid elevates the sternum, and, when the arms are fixed, pectoralis major can assist by expanding the chest further. This coordinated action increases thoracic volume in multiple directions, creating the negative pressure that draws air into the lungs. The bones themselves—such as the sternum, ribs, and vertebrae—provide the framework, but the pumping effect comes from these muscles expanding the chest. Internal intercostals and abdominal muscles are more linked to expiration or stabilization, not the primary inspiratory pump. The “front of the body” option doesn’t describe the muscular mechanism involved.

The respiratory pump works by muscles that move the rib cage and sternum to enlarge the chest cavity for inhalation. The diaphragm contracts and moves downward, increasing vertical space. The external intercostals lift the ribs, widening the thorax. Accessory inspiratory muscles—scalenes lift the top ribs, sternocleidomastoid elevates the sternum, and, when the arms are fixed, pectoralis major can assist by expanding the chest further. This coordinated action increases thoracic volume in multiple directions, creating the negative pressure that draws air into the lungs. The bones themselves—such as the sternum, ribs, and vertebrae—provide the framework, but the pumping effect comes from these muscles expanding the chest. Internal intercostals and abdominal muscles are more linked to expiration or stabilization, not the primary inspiratory pump. The “front of the body” option doesn’t describe the muscular mechanism involved.