General Anatomy, lung mechanics Flashcards

1
Q

What three structures make up the sternum?

A

Manubrium, body and xiphoid process

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2
Q

How are ribs 8-10 connected to the sternum?

A

They are not - they are connected to the costal cartilage above.

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3
Q

Which four ribs are considered atypical and why?

A

1 - shortest, broadest, most curved, single articular facet, two superior grooves for subclavian vessels
2 - poorly marked costal groove, serratus anterior attaches to superior surface
11/12 - single articular facet, no tubercle, tapering anterior end

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4
Q

What are the two types of joint between ribs and vertebrae?

A

Costotransverse joint and costovertebral joint

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5
Q

Describe the costotransverse joint.

A

Between the tubercle of the rib and the transverse process of vertebrae

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6
Q

Describe the costovertebral joint.

A

Between the head of the rib, the superior costal facet of the corresponding vertebra and the inferior costal facet of the superior vertebra

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7
Q

What are the three layers of the intercostal muscles?

A

External intercostal - inferoanteriorly
Internal intercostal - inferioposteriorly
Innermost intercostal

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8
Q

What is the function of the external intercostal muscle?

A

Elevates ribs to increase thoracic volume

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9
Q

What thin strips of muscle are similar in structure, function and innervation to the innermost intercostal muscles?

A

Subcostals

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10
Q

Does elevation of the upper ribs increase AP diameter or lateral diameter?

A

AP diameter

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11
Q

What movement increases lateral diameter of the thorax?

A

Bucket handle type movement of lower ribs

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12
Q

Which muscles depress the ribs during forced expiration?

A

Innermost and internal intercostal muscles

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13
Q

What separates the internal intercostal muscles and innermost intercostal muscles?

A

Neurovascular bundle

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14
Q

Describe the arterial supply to intercostal muscles.

A

Posterior intercostal arteries from thoracic aorta and anterior intercostal arteries from internal thoracic artery anastomose to supply muscles, parietal pleura and overlying skin.

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15
Q

Where does venous return drain into?

A

Azygous system

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16
Q

What are the three peripheral attachments of the diaphragm?

A
  1. Xiphoid process
  2. Costal cartilages of ribs 7-12
  3. Lumbar vertebrae and arcuate ligaments
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17
Q

What forms the central tendon and where does it fuse to?

A

Muscles of the diaphragm combine to form central tendon and fuse with inferior fibrous pericardium

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18
Q

Which muscle accounts for the majority of chest expansion during inspiration?

A

Diaphragm

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19
Q

At what level does the oesophagus pass through the diaphragm?

A

T10

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20
Q

At what level does the IVC pass through the diaphragm?

A

T8

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21
Q

At what level does the aorta pass through the diaphragm?

A

T12

22
Q

What accompanies the aorta through the aortic hiatus in the diaphragm?

A

Thoracic duct and azygous vein

23
Q

What accompanies the oesophagus through the oesophageal opening in the diaphragm?

A

Vegas nerves and oesophageal branches of the left gastric vessels

24
Q

Describe the sensory supply of the phrenic nerve.

A

Pericardial, mediastinal part of parietal pleura, diaphragmatic part of parietal pleura and both surfaces of the diaphragm

25
Q

From which spinal roots does the phrenic nerve arise?

A

C3-C5

26
Q

Describe the arterial supply to the diaphragm.

A

Inferior phrenic arteries, superior phrenic arteries, pericardiacophrenic arteries, musculophrenic arteries

27
Q

Which accessory muscles are used in forced inspiration?

A

Scalene, sternocleidomastoid, pec major and serratus anterior

28
Q

Why is expiration passive?

A

Due to the elastic recoil of chest wall and lungs

29
Q

Explain the purpose of the film of fluid between pleural layers.

A

Allows the pleural layers to slide over each other. During inspiration, the fluid molecules resist being pulled apart so expansion of parietal pleura pulls out visceral pleura and lungs also, allowing chest to expand.

30
Q

At what level does the trachea end?

A

T4/T5

31
Q

What muscle lines the trachea posteriorly

A

Trachealis

32
Q

Describe the sequence of the bronchial tree.

A

Trachea, main bronchi, lobar bronchi ( 3 right, 2 left), segmental bronchi

33
Q

What is the importance of a bronchopulmonary segment?

A

It can be surgically isolated and removed with minimal damage to other segments.

34
Q

What are the three surfaces of the lungs?

A

Costal surface, diaphragmatic surface, mediastinal surface

35
Q

What is the significance of the apex of the lung extending into the root of the neck?

A

Apical lung tumours can affect structures such as the brachial plexus (Especially medial cord), subclavian vessels and sympathetic trunk

36
Q

How do the lungs receive sympathetic nerve supply?

A

They receive fibres from the vagus nerve and sympathetic trunk via the pulmonary plexuses at each hilum.

37
Q

At the resting expiratory level, what forces are all in balance?

A

Forces pulling the lungs in, thoracic cage out and passive stretch of diaphragm down

38
Q

Why is breathing out to resting expiratory level passive?

A

Lungs recoil which does not require any energy

39
Q

Why do we need to reduce intrathoracic pressure during inspiration?

A

So that it falls below atmospheric pressure so that air can flow into the lungs

40
Q

Why is the intrapleural pressure always negative?

A

Because the chest wall is always trying to expand and the lungs are always to trying to collapse.

41
Q

When is inspiration a passive a process?

A

Returning to resting expiratory level after forced expiration.

42
Q

What is compliance?

A

Stretchiness of the lungs

43
Q

Why does an increase in compliance make it harder to expirate?

A

Lungs are easier to stretch so they don’t recoil so readily

44
Q

What is the relationship between elastic recoil and compliance?

A

Elastic recoil is inversely proportional to compliance

45
Q

Why do type 2 pneumocytes release surfactant?

A

Surfactant decreases surface tension in the fluid lining alveoli which makes them easier to stretch.

46
Q

What creates surface tension?

A

Attraction of water molecules to each other in the fluid

47
Q

Between what two structures is the sternal angle located?

A

Manubrium and body of the sternum

48
Q

Why is it easier to take smaller breaths than big breaths?

A

When lungs are inflated, surfactant molecules are more spread out so they are not as effective at reducing surface tension whereas when lungs are deflated, surfactant molecules are better at reducing surface tension because they are closer together.

49
Q

Explain Laplace’s law.

A

Radius is inversely proportional to pressure. If a big bubble is connected to a small bubble, air will flow from the area of higher pressure to lower pressure, i.e. the smaller bubble will collapse into the bigger bubble.

50
Q

Why doesn’t Laplace’s law cause small alveoli to collapse into big alveoli?

A

Because as alveoli get bigger, surface tension increases as surfactant becomes less effective so pressure stays high and stops them collapsing little alveoli