Role of the Intercostal Muscles & Diaphragm

Ventilation

Movement of air into and out of the lungs

Inhalation

Breathing in

Exhalation

Breathing out

Diaphragm

Dome‑shaped muscle at the base of the lungs

External intercostal muscles

Muscles that lift the ribcage during inhalation

Internal intercostal muscles

Muscles that pull the ribcage down during forced exhalation

Ribcage

Protects lungs and moves during breathing

Thoracic cavity

Chest space where lungs expand and contract

Air pressure

Force exerted by air inside the lungs

What happens to the diaphragm during inhalation?

It contracts and flattens

What happens to the external intercostal muscles during inhalation?

They contract

What happens to the ribcage during inhalation?

Moves up and out

What happens to thoracic volume during inhalation?

It increases

What happens to air pressure in the lungs during inhalation?

It decreases

Why does air enter the lungs during inhalation?

Air moves from high to low pressure

What happens to the diaphragm during exhalation?

It relaxes and domes up

What happens to the external intercostal muscles during exhalation?

They relax

What happens to the ribcage during exhalation?

Moves down and in

What happens to thoracic volume during exhalation?

It decreases

What happens to air pressure in the lungs during exhalation?

It increases

Why does air leave the lungs during exhalation?

Air moves from high to low pressure

Which muscles are used in forced exhalation?

Internal intercostal muscles

What do internal intercostal muscles do?

Pull the ribcage down forcefully

Why is forced exhalation needed?

During exercise or blowing out air

Why must the diaphragm and intercostal muscles work together?

To change lung volume and create pressure differences