Respiratory Movements

• Respiratory movements are classified as eupnea or hyperpnea, based on whether expiration is passive or active
• During eupnea, expansion of the lungs stretches their elastic fibers
• Elevation of the rib cage stretches skeletal muscles and elastic fibers in the connective tissues of the body wall
• When inspiratory muscles relax, elastic structures recoil, returning diaphragm and rib cage to original positions
• During diaphragmatic breathing, or deep breathing, contraction of the diaphragm provides necessary change in thoracic volume
• In costal breathing, or shallow breathing, the thoracic volume changes because the rib cage changes shape
• During hyperpnea, accessory muscles assist with inspiration, and expiration involves contraction of the transversus thoracis and internal intercostal muscles
• SUMMARY - Respiratory Muscles

  • Pulmonary ventilation is movement of air of lungs. Important respiratory muscles are diaphragm, external / internal intercostal. Contraction of diaphragm increases volume of thoracic cavity; external intercostals assist in inspiration by elevating ribs; internal intercostals depress ribs and reduce thoracic cavity for expiration. Accessory respiratory muscles active when depth and frequency of respiration to be increased. Accessory muscles are sternocleidomastoid, serratus anterior, transversus thoracis, scalene, pectoralis minor, oblique, rectus abdominis.
• Athletes commonly try to catch their breath after strenuous exercise by standing with their hands on their thighs while breathing deeply. Is this the best way to increase the flow of air into their lungs?

  No. In order to increase the flow of air into their lungs, athletes should stand upright and use their diaphragm, external intercostals, and accessory respiratory muscles to increase the size of their thoracic cavity as much as possible.