SUPERIOR MEDIASTINUM Flashcards

1
Q

Boundaries of superior mediastinum and their location

A

Anterior - manubrium
Inferior - Line from sternal angle to T4/T5 disc
Posterior - T1-T4 vertebrae
Superior - Thoracic inlet

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2
Q

Contents of superior mediastinum

A
  • Thymus
  • Brachiocephalic veins, SVC
  • Aorta - Brachiocephalic a., L common carotid a., L subclavian a.
  • Vagus and Phrenic nerves
  • Trachea
  • Esophagus
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3
Q

Location of thymus

A

beneath sternum - in superior and anterior mediastinum

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4
Q

Thymus in children

A

functional

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5
Q

Thymus in adults

A

involution

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6
Q

Brachiocephalic veins are formed by the union of

A

internal jugular and subclavian veins

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7
Q

L and R brachiocephalic veins join to from the

A

SVC

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8
Q

L brachiocephalic vein course and location

A

long horizontal course (SVC is R shifted) - posterior to manubrium

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9
Q

L brachiocephalic vein tributaries

A

IJV, subclavian, internal thoracic vein, thoracic duct

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10
Q

R brachiocephalic vein course and location

A

short vertical course – lateral to brachiocephalic artery

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11
Q

R brachiocephalic vein tributaries

A

IJV, subclavian, Internal thoracic vein, R lymphatic duct

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12
Q

What tributaries differ between R and L brachiocephalic veins?

A

L = thoracic duct, R = R lymphatic duct
same = IJV, subclavian, Internal thoracic vein

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13
Q

SVC is formed by the union of

A

R and L brachiocephalic veins

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14
Q

SVC ends at

A

R atrium

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15
Q

What structures are anterior to SVC?

A

portion of R lung + associated pleura

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16
Q

What structures are posterior to SVC?

A

R Vagus nerve, R pulmonary artery, R main bronchus, azygos vein

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17
Q

What structures are medial to SVC?

A

Ascending aorta

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18
Q

What structures are lateral to SVC?

A

R phrenic nerve

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19
Q

What is the major clinical correlate of the SVC?

A

SVC Syndrome

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20
Q

SVC Syndrome

A

Any disease process that results in compression of SVC = Obstruction
- Increased pressure in venous system draining into SVC
- Fluid leaks out of venous system into interstitial tissues = Swelling or Edema
- Affects upper limbs, head and neck (including brain)

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21
Q

SVC most commonly occurs due to what? What else could cause this?

A

lung cancer in RUL
others: enlarged lymph nodes (lymphoma) or aortic aneurysm (swelling of heart)

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22
Q

What veins drain into the SVC?

A

veins from arm/head/neck

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23
Q

4 parts of the aorta

A

Ascending, Arch, Descending Thoracic, and Abdominal

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24
Q

What type of vessel is the aorta?

A

strong, high-pressure vessel

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25
Q

Where does the Ascending aorta start and end?

A

beings at aortic valve (3rd L costal carotid), ends at 2nd R costal carotid - becomes aortic arch

26
Q

Branches of ascending aorta

A

L and R coronary arteries

27
Q

What structure is lateral to the ascending aorta?

A

SVC

28
Q

Where does the aortic arch start and end?

A

starts and ends at T4/T5 vertebral disc, arches posteriorly over pulmonary trunk and L main bronchus

29
Q

Branches of the aortic arch

A

brachiocephalic, L common carotid, L subclavian arteries

30
Q

What structures are anterior to the aortic arch?

A

L Vagus and phrenic nerves + L recurrent laryngeal nerve

31
Q

What structures are posterior to the aortic arch?

A

trachea/bifurcation, esophagus

32
Q

What is the main clinical correlate to the aorta?

A

aortic aneurysm

33
Q

Aortic Aneurysm

A

Dilation of the aorta – often asymptomatic but if large enough may produce symptoms by affecting nearby structures
if ruptures = high mortality

34
Q

Outcome of aortic aneurysm in the ascending portion of the aorta

A

compression of SVC

35
Q

outcome of aortic aneurysm in the aortic arch

A
  • Stretches L recurrent laryngeal nerve = hoarse voice
  • Compresses trachea/L bronchus = cough, wheezing
  • Compresses esophagus = dysphagia (difficulty swallow)
36
Q

What nerve supplies the vocal cord?

A

laryngeal nerve

37
Q

Brachiocephalic aortic branch becomes ________ at _____

A

becomes R common carotid and subclavian arteries at sternoclavicular joint

38
Q

What structures are anterior to the brachiocephalic branch of the aortic arch?

A

L brachiocephalic vein

39
Q

What structures are posterior to the brachiocephalic branch of the aortic arch?

A

trachea

40
Q

What structures are anterior to the L common carotid branch of the aortic arch?

A

L brachiocephalic vein

41
Q

What structures are posterior to the L common carotid branch of the aortic arch?

A

trachea and L recurrent laryngeal nerve

42
Q

What structures are lateral to the L common carotid branch of the aortic arch?

A

L vagus nerve and L phrenic nerve

43
Q

L subclavian branch of aortic arch runs ____ and exits ____

A

runs lateral to trachea and L common carotid and exits superior to mediastinum at sternoclavicular joint

44
Q

Vagus nerve is located in the

A

mediastinum

45
Q

Vagus nerve gives rise to

A

cardiac, pulmonary, esophageal plexuses in thorax (parasympathetic innervation)

46
Q

R vagus nerve travels

A

posterior to SVC

47
Q

R vagus nerves gives ____ at _______

A

Gives R recurrent laryngeal nerve branch at junction of brachiocephalic and R subclavian arteries

48
Q

L vagus nerves travels lateral, posterior, and anterior to what structures?

A

travels lateral to L common carotid
travels posterior to L brachiocephalic vein
and anterior to aortic arch

49
Q

L vagus nerve gives _____ at _____

A

Gives L recurrent laryngeal nerve branch at aortic arch

50
Q

Phrenic nerve innervates what vertebrae?

A

C3, C4, C5

51
Q

Phrenic nerve innervates the

A

diaphragm

52
Q

Phrenic nerve originates in the

A

diaphragm

53
Q

R phrenic nerve runs

A

lateral to SVC, then along pericardium

54
Q

L phrenic nerve runs

A

under L brachiocephalic vein and over aortic arch, then along pericardium

55
Q

Trachea is made of

A

fibrocartilage

56
Q

What vertebral levels does the trachea start and end at?

A

C6 to T4/T5 disc

57
Q

What structures are anterior to the trachea?

A

arch of aorta, (brachiocephalic artery, L common carotid), cardiac plexus, L brachiocephalic vein, pulmonary arteries

58
Q

What structures are posterior to the trachea?

A

esophagus

59
Q

What structures are on the R side of the trachea?

A

R Vagus, azygos vein, SVC, (brachiocephalic artery)

60
Q

What structures are on the L side of the trachea?

A

L recurrent laryngeal nerve, arch of aorta (L common carotid)

61
Q

Where does lymphatic drainage of the trachea occur?

A

pre and para-tracheal lymph node