Anatoy of the thorax

Question 1

What are your body cavities lined with?

Answer 1

Serous membranes

Question 2

What is the serous membrane?

Answer 2

A layer of epithelial cells that secrete a watery fluid
* Double layer of secretory
tissue with fluid between
layers

Question 3

Parts of the serous mem

Answer 3

• Visceral layer on the
  organ
• Parietal layer on body
  wall

Question 4

What cavities does the thoracic cavity have?

Answer 4

The 2 pleura + pericardium in the mediastinum

Question 5

What cavity is in the abdominopelvic area

Answer 5

Peritoneum

Question 6

What are the boundaries of the thoracic cavity?

Answer 6

• Anterior: Sternum
• Posterior: Thoracic
  vertebrae
• Lateral: Ribs
• Superior: base of neck
• Inferior: diaphragm

Question 7

What is everything below the diaphragm a part of

Answer 7

Peritoneum

Question 8

What is the parietal pleura connected to?

Answer 8

The thoracic wall

Question 9

What is ventilation driven by?

Answer 9

Pressure changes

Question 10

Relationship between P and V

Answer 10

Inverse relationship aka Boyles law

Question 11

Boyles law

Answer 11

• Pressure measured by
  collisions:
• smaller space = more
  collisions = increased
  pressure
• bigger space = less
  collisions = decreased
  pressure

Question 12

Where will air move

Answer 12

To the area with low pressure

Question 13

Boyles law

Answer 13

*Between breaths: P inside = P outside so no gradient
* Increase volume (therefore
decrease pressure) – air
flows in
* Decrease volume (therefore
increase pressure) - air
flows out

Question 14

How are the ribs connected to the sternum?

Answer 14

Through the costal cartilage
- Hyaline cartilage
- Either synovial or cartilaginous jointsS

Question 15

Sternocostal joints

Answer 15

• 3 joints

All Synovial
- Except 1st = cartilaginous

Question 16

Why is the 1st sternocostal joint cartilaginous

Answer 16

To provide stability at the base of the neck under the clavicle

Question 17

Costochondral joints are:

Answer 17

Cartilaginous joints

Question 18

Interchondral joints

Answer 18

Joints between cartilage
- Synovial that allows for movement of the ribs

Question 19

Articulations between the ribs and vertebrae are:

Answer 19

Synovial joints

Question 19

Costotransverse

Answer 19

between rib and transverse
process of vertebrae

Question 20

Costovertebral

Answer 20

between rib and body of vertebrae

Question 21

1º muscles of respiration

Answer 21

Diaphragm and the intercostals

Question 22

When are accessory muscles active

Answer 22

Only when needed

Question 23

The diaphragm

Answer 23

• Sheet of skeletal muscle
• Separates thorax from
  abdomen
• Dome-shaped when relaxed
• Flattens when contracted
• Contraction expands thoracic
  cavity, compresses
  abdominopelvic cavity
  1º muscle of inspiration

Question 24

Intercostal muscles

Answer 24

Attach diagonally
between neighbouring
ribs
* External intercostals
* Lift ribcage and
expand cavity
* Inspiration- quiet and
forced
Internal intercostals
* Depress ribcage and
decrease cavity i.e lowers ribcage
* Expiration- forced only

Question 25

Accessory muscles

Answer 25

• Several muscles i.e a group that
  attach to the thoracic cage
• Some accessory muscles
  increase cavity volume for
  forced inspiration
• Other accessory muscles
  decrease cavity volume for
  forced expiration

Question 26

What happens during inspiration

Answer 26

• During normal ‘quiet’
  inspiration
• Diaphragm contracts =
  flattens
• External intercostals
  contract = lifts ribs
• During active ‘forced’
  inspiration
• As above, plus
  accessory muscles
  contract to further
  expand thoracic cavityW

Question 27

What happens during expiration?

Answer 27

• During normal ‘quiet’
  expiration
• Passive process
• Diaphragm relaxes = dome
  shaped
• External intercostals relax =
  ribs no longer lifted
• During active ‘forced’
  expiration
• As above plus:
• Internal intercostals contract =
  depress ribs
• Accessory muscles contract
  to further decrease cavity
  volume

Question 28

How do the lungs expand as the
cavity does?

Answer 28

• Lung tissue is elastic and
  always trying to recoil
• The pleura make the
  lungs ‘stick’ to the thoracic
  wall
• Lungs expand during
  inspiration
• Lungs contract during
  expiration

Question 29

Thoracic Movement: Pleura

Answer 29

Visceral pleura on lungs
* Parietal pleura on thoracic wall
* Pleural fluid in between
– Slippery surface for frictionless movement against other structures
– Fluid bond causes lungs to ‘stick’ to thoracic wall
* Therefore, thoracic wall movement results in lung movement
– Increase volume of thorax increase volume of lung decrease
pressure in lung air flows in
M

Question 30

Pneumothorax

Answer 30

• Air collects in pleural
  space
• The collapse of part or
  the entire lung
• Physical trauma or as
  spontaneous response
  to lung disease