Thoracic cage and Abdominal wall

Pleura

Lungs are anchored to the body wall via membrane called pleura

this leaves lungs under tension

What contributes to breathing

Anything that changes volume of thoracic cavity

What is/does increase and decrease of volume cause?

Increase of volume:

• caused by depression of diaphragm

• causing inspiration

Decrease of volume:

• caused by elevation of diaphragm

• causing expiration

During quiet respiration (at rest):

Diaphragm contracts (flattens)

• Depresses abdominal contents

• Increases space in thorax creates vacuum

• Air rushes into lungs

Diaphragm relaxes

• Lungs recoil

• Air rushes out

At rest, diaphragm is the primary muscle of respiration

What innervates diaphragm, what dermatome?

During exertion (increased lung volume)

Additional muscles are recruited

• elevates ribs and sternum

• even more space in thorax = creates stronger vacuum

• Even more air rushes into lungs

Thoracic cage expansion during breathing at exertion

The thoracic cage expands equally in all dimensions when breathing at exertion

Paradoxical breathing

• abnormal breathing pattern where the chest contracts while abdomen rises during inhalation

• happens due to injured phrenic nerve

• elevation of the diaphragm on the affected side

Diastasis Recti

• Is separation of the rectus abdominis mm. at the linea alba due to abdominal straining

• common during pregnancy