BI-1042
The breathing system
Biology · Secondary 3 · Medium · The breathing system
During inhalation, which coordinated actions of the intercostal muscles and ribcage help draw air into the lungs?
- External intercostal muscles contract and ribs move upwards and outwards.
- External intercostal muscles relax and ribs move downwards and inwards.
- Internal intercostal muscles contract and ribs move downwards and inwards.
- Internal intercostal muscles relax and ribs move upwards and outwards.
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