Biology for IGCSE & O level - Gas Exchange In Humans (Section 1 - No. 22)
What happens to the intercostal muscles during inhalation?
They relax.
They contract, lifting the ribs upwards and outwards.
They contract, pulling the ribs downwards and inwards.
They remain unchanged.
Explanation
The contraction of the external intercostal muscles raises the rib cage, increasing the volume of the chest cavity and drawing air in.
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