Ventilation

The ribs, intercostal muscles and diaphragm all play important roles in ventilation (breathing).

Breathing in

When you inhale:

  1. the internal intercostal muscles relax and the external intercostal muscles contract, pulling the ribcage upwards and outwards
  2. the diaphragm contracts, pulling downwards
  3. lung volume increases and the air pressure inside decreases
  4. air is pushed into the lungs

Breathing out

When you exhale:

  1. the external intercostal muscles relax and the internal intercostal muscles contract, pulling the ribcage downwards and inwards
  2. the diaphragm relaxes, moving back upwards
  3. lung volume decreases and the air pressure inside increases
  4. air is pushed out of the lungs
An illustration showing the elements involved in breathing. Labelled are the Nasal cavity, Pleural cavity, Intercostal muscles, Ribs, Diaphragm, Trachea, Lung, Bronchus, Bronchiole and Alveoli.

Ventilation

The elements involved in breathing