Lecture 13: Structures of thorax and ventilation.

Question 1

What are the muscles of respiration?

Answer 1

1. Diaphragm
2. Intercostals: external or internal
3. Accessory muscles

Question 2

What are pleura?

Where are they located?

Answer 2

Pleura(a type of serous membrane) lines the thoracic cavity and secretes serous fluid into the pleural cavity
viseral pleura: covers lungs
parietal pleura: lines thorax, mediastinum

Question 3

What is the function of pleura?

Answer 3

Pleura secrete pleura fluid(serous) which allows for low friction movement of the lungs and reduces surface tension and adhesion

Question 4

During inspiration what happens to the diaphragm?

Answer 4

= increases thoracic cavity length

• contracts
• flattens inferior, increases volume capacity and in length

Question 5

During inspiration what happens to the external intercostals?

Answer 5

= increase thoracic cavity volume

• contracts
• elevates rib cage and pulls sternum forward
• thoracic cavity increase in width, depth and volume

Question 6

What happens during inspiration?

Answer 6

respiratory muscles CONTRACT - diaphragm flattens ( at rest it is dome shaped) - thorax size and volume increases

Question 7

What happens during expiration?

Answer 7

= RELAXATION - decrease in thorax size/volume

• respiratory muscles relax = passively
• requires alveolar pressure higher than atmospheric pressure
• increase in alveoli pressure - air flows out
• thorax size and volume capacity decreases
• Elastin for recoil

Question 8

Describe the boundaries of the thoracic cavity?

• Superior
• Inferior
• Lateral

Answer 8

Superior: root of neck
Inferior: Diaphragm
Lateral: Ribs/Intercostals

Question 9

Describe the anterior boundary of the thoracic cavity?

What are the anterior joints?
What do they connect to?

Answer 9

Anterior = sternum
Sternocostal: synovial joints
Costochondral: cartilaginous joints
Interchondral: synovial joint
= connect to the sternum

Question 10

Descrive the posterior boundary of the thoracic cavity?

What posterior joints are there?
What do they connect to?

Answer 10

Posterior: vertebrae
- Articulation btw thoracic vertebrae and ribs
- Bilateral facets
- Synovial joints: Costatransverse(connect to the transverse process of the vertebra) & Costovertebral(connect to medial aspect of the vertebrae)
=connect to the vertebra

Question 11

what muscles assist with forced expiration and inspiration?

Answer 11

Forced inspiration = accessory muscles

Forced expiration = INTERNAL intercostals and accessory muscles