Mammoth Memory

The Diaphragm

The diaphragm is a dome-shaped muscle separating the chest cavity (thorax) and the abdomen. The diaphragm is shaped like a parachute. 

The diaphragm is a large muscle that separates the thorax from the abdomen

She grabbed at the diagram (diaphragm) and used it to build a parachute.

When you breathe in, your diaphragm contracts (tightens) and moves downwards until flat. At the same time, your intercostal muscles pull the ribs upwards and outwards, helping to enlarge the chest cavity.

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This diagram shows clearly how parachute-shaped the diaphragm is.

 Diagram showing the action of the diaphragm while breathing in and out

When the diaphragm contracts, it flattens to make the chest cavity larger and air is drawn into the lungs. When it relaxes, air is expelled from the lungs.

Infographic showing the volume of the thorax while breathing also the action of the diaphragm

Contracting and relaxing the diaphragm increases and decreases the size of your thorax.

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