Review of the gross anatomy of the thorax

Question 1

Components of bony skeleton of the thorax

Answer 1

• 12 pairs of ribs
• vertebrae posteriorly
• sternum anteriorl

Question 2

How the chest wall would like to move naturally

Answer 2

Would naturally like to spring outwards (think about cracking chest open during surgery or doing CPR)

Question 3

Muscles of the thorax

1) location (what do they cover -2)
2) Function
3) What muscles are included? (2)

Answer 3

-cover the thoracic outlet and the intercostal spaces
-act to increase and decrease intrathoracic volume
include diaphragm and intercostal (external and internal)

Question 4

Importance changes in intrathoracic volume (what do they drive)

Answer 4

-these changes lead to changes intrathoracic pressures that drive flow of air to and from the lungs

Question 5

Muscles involved in quiet inspiration (2)

Answer 5

Diaphragm

External intercostals

Question 6

Muscles involved in forced inspiration (3)

Answer 6

Diaphragm
External intercostals
Accessory muscles (scalenes, sternocleidomastoid)

Question 7

Muscles involved in quiet expiration (+ why)

Answer 7

• passive (does not involved muscular contraction)

- because lungs naturally want to collapse inwards

Question 8

Muscles involved in forced expiration (4)

Answer 8

• internal intercostals
• abdominal muscles
• neck and back muscles

Question 9

Pleural cavity (what it includes in an adult)

Answer 9

-reduced to potential spaces = intrapleural spaces

Question 10

What would happen if open the chest wall in the living? What does this mean for the pressure inside the intrapleural space?

Answer 10

• chest would spring outwards and lungs would collapse/recoil inwards
• therefore acting like a sort of suction/partial vaccum - pressure inside this is below atm therefore intrapleural pressure must be below atm pressure

Question 11

Bronchial tree divisions (5 notable divisions)

Answer 11

1) Trachea
2) Left and Right main bronchi (level sternal angle)
3) Secondary/lobar bronchi
4) divides all the way to 16th division = terminal bronchioles (smallest parts of bronchial tree without alveoli)
5) Beginning at 17th division onward = gas exchange regions of bronchial tree
6) Alveolar sacs at 23rd division

Question 12

Function of conducting airways

Answer 12

• first 16 divisions

- no alveoli therefore do not play a part in gas exchange -just transmit inspired air to gas exchanging regions

Question 13

Anatomical dead space

Answer 13

-name given to the 1/3 of air inspired that ends up staying in conducting airways (simply filling up these areas= does not play a role in gas exchange)

Question 14

Function of respiratory zone

Answer 14

• from 17th division

- contain alveoli = region where gas exchange takes place