Breathing/ventilation

internal and external intercostal muscles


Inspiration

  • external intercostal muscles contract

  • pulls ribcage upwards

  • diaphragm contracts

    • domed → flat shape

  • volume of thorax and lungs increases

  • pressure decreased

  • air enters down pressure gradient


  • inspiration


Expiration (relaxed)

  • external intercostal muscles relax

  • ribcage falls under own weight

  • diaphragm relaxes and abdominal pressure pushes it back to domed shape

  • elastic recoil of lung tissue

  • volume of thorax and lungs decreases

  • pressure is increased

  • air is forced out


  • expiration (relaxed)


Expiration (forced)

  • internal intercostal muscles contract

  • pulls ribcage in and down

  • abdominal muscle contracts and pushes diaphragm upwards

  • volume of thorax and lungs decrease

  • pressure increased

  • air forced out

  • takes place during exercise and singing


  • expiration (forced)