Thorax, Tracheobronchial Tree & Lungs (Part 1) Flashcards

1
Q

What is the thorax?

A

Irregularly cylindrical cavity with openings at top & bottom composed of a thoracic wall, pleural cavities & mediastinum

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2
Q

What are the functions of the thorax?

A

Passageway between abdomen & neck/upper limb for vessels & nerves

Protection of organs

Breathing

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3
Q

What are the 2 openings of the thorax called?

A

Superior thoracic aperture

Inferior thoracic aperture

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4
Q

What is the bottom boundary of the thorax?

A

Diaphragm

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5
Q

What is within the mediastinum?

A

Heart

Great vessels

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6
Q

How does the thoracic wall allow breathing?

A

Able to withstand a range of positive & negative pressures during breathing

Mobile structure but with structural rigidity

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7
Q

Describe the structure of the ribs.

A

12 paired ribs with intercostal muscles in between

Ribs 1-10 end in costal cartilage whilst 11-12 embedded in muscle

Articulate with thoracic vertebra posteriorly around the thoracic inlet and connect to the sternum via costal cartilage anteriorly with variable articulations

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8
Q

Why can ribs move?

A

Articulation of ribs have synovial joints

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9
Q

What will happen if the ribs are fractured in terms of breathing?

A

Paradoxical movement of thoracic wall segment at point of fracture; ribs will not move normally e.g. they will depress rather than expand in inspiration

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10
Q

What is the lower border of the costal cartilage called?

A

Costal margin

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11
Q

What structures go through the thoracic apertures?

A

Part of brachial plexus

Subclavian vessels

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12
Q

What can happen if you are born with an cervical rib (at C7 instead of T1)?

A

May compress brachial plexus -> 1st dorsal webspace of hands looks deflated as these muscles are innervated by the brachial plexus and they atrophy due to lack of stimulation

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13
Q

What parts make up the sternum from the top down?

A
Suprasternal (jugular) notch (T2)
Manibrium
Manubrio/sternal angle (T4/5)
Body
Xiphoid process (T9/10)
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14
Q

What bit of the sternum is useful to palpate? What does this give you an indication of?

A

Sternal angle

Indicates that the 2nd costal cartilage is lateral & the sternal plane (T4/T5 IV disc)

Also divides sternum & mediastinum into superior & inferior parts

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15
Q

Are fractures of the sternum common?

A

No, usually only seen with serious of fatal injury

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16
Q

Where are the costal grooves of the rib? Why are they relevant?

A

On inferior margin

Where neurovascular bundle runs (collateral & accessory bundles inferior too)

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17
Q

What is the rib angle useful for?

A

Used by anaesthetists as a landmark to perform intercostal nerve blocks

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18
Q

What is in the neurovascular bundle in order?

A

V: Vein
A: Artery
N: Nerve

19
Q

What do most ribs articulate with?

A

Bodies of their own vertebra (w/ synovial joints) AND one above it AND with transverse process of their own

20
Q

What are the 3 classifications of the ribs and what ribs does each one cover?

A
  1. Vertebrosternal (ribs 1-7)
  2. Vertebrocostal (ribs 8-10)
  3. Floating ribs (ribs 11-12)
21
Q

What are the 3 layers of intercostal muscles that fill the intercostal spaces?

A
  1. External intercostal muscle
  2. Internal intercostal muscle
  3. Innermost intercostal muscle
22
Q

What muscle layers does the neurovascular bundle run between?

A

Internal & innermost intercostal muscles

23
Q

What is the function of the intercostal muscles?

A

Provide support & contribute to thoracic wall movements

24
Q

What muscles control inspiration and expiration mainly? What do they do?

A

Inspiration: external intercostal muscles (move downwards)

Expiration: internal intercostal muscles (move upwards)

25
Q

Where should chest drains be inserted? Why?

A

Inferior part of intercostal spaces to avoid damaging the MAIN neurovascular bundle

26
Q

What layer is on the inside of the innermost intercostal muscle?

A

Endothoracic fascia

27
Q

Where do the intercostal nerves come from and what do they innervate?

A

Ventral rami of spinal nerves

Provide motor & sensory to the intercostal space & surrounding tissue (e.g. skin, cartilage, bone, muscle & parietal pleura)

28
Q

Why is the dermatomal arrangement of intercostal nerves relevant clinically?

A

Pleuritic pain can refer to dermatome

Shingles can distribute to dermatome

29
Q

Where does the sympathetic chain run?

A

Along posterior thoracic wall (T1-L2)

30
Q

What can compress the sympathetic chain in its apical region? What can this cause? Why?

A

Pancoast tumour i.e. apical lung tumour

-> Horner’s syndrome; this chain sends branches to head & neck so symptoms will show in face mainly e.g. ptosis, miosis & loss of hemifacial sweating (on same side as tumour)

31
Q

Describe the arrangement of the anterior (AIA) and posterior intercostal arteries (PIA).

A

PIA from descending aorta & AIA from internal thoracic artery + musculophrenic -> join to form anastomosis in middle

Allows a collateral circulation that can provide a potential bypass in aortic coarctation

32
Q

What can the internal thoracic arteries (ITA) be used for? Why?

A

Coronary artery bypass grafting (CABG) because ITA resists plaque build up better than most arteries in body so good to harvest & replace a artery that doesn’t work anymore

33
Q

How is the thoracic wall drained?

A

Unpaired azygous system:

  • Upper intercostal spaces drain directly in brachiocephalic veins -> subclavian veins
  • Right sided structures drain in azygous vein -> SVC
  • Left sided structures drain via accessory azygous/hemiazygous veins-> cross midline into azygous -> SVC
34
Q

Where is the thoracic duct? What does it do?

A

Runs through posterior & superior mediastinum, anterior to vertebral bodies

Drains majority of bodies lymph fluid into left subclavian vein

35
Q

What is special about the left subclavian vein?

A

Extra supraclavicular nodes sit around this region due to the amount of lymph fluid draining at this point

36
Q

What is the diaphragm?

A

Muscular & tendinous structure that domes into the thoracic cavity & fills inferior thoracic aperture

37
Q

What are the characteristic features of the diaphragm?

A

Right & left domes

  • Central tendinous part for heart
  • Attaches to costal margin & ribs 10-12
  • Diaphragmatic crura attach to lumbar vertebrae
38
Q

What happens to the diaphragm during inspiration?

A

Drops down & flattens = thoracic cavity volume increases -> decreased pressure allowing air to move into the lungs

39
Q

Describe the innervation of the diaphragm.

A

Phrenic nerve (C3-5) provides motor & sensory

Additional sensory innervation on periphery from intercostal nerves

40
Q

What will occur if there is unilateral damage to the phrenic nerve?

A

Hemidiaphragmatic palsy

41
Q

Where can gallbladder inflammation cause pain?

A

Shoulder due to the phrenic nerve

Regional pain in right hypochrondium due to intercostal nerve

As its in the midclavicular line around the 9th rib

42
Q

What structures pierce the diaphragm? Why can this be problematic?

A

IVC (T8)
Oesophagus (T10-12)
Aorta (T12)

Creates relative weak spots through which a sliding or rolling hernia can form

43
Q

Where can congenital diaphragmatic defects occur?

A

Posterolaterally (Bochdalek): part of liver pops up into diaphragm

Retrosternally (Morgagni): tranverse colon & greater omentum coming up behind diaphragm behind midline of sternum

If severe must be fixed early in life

44
Q

The diaphragm separates the thoracic cavity from the ___ __.

A

Abdominal cavity