Lecture 18: Anterior, Superior, and Posterior Mediastinum Flashcards Preview

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Flashcards in Lecture 18: Anterior, Superior, and Posterior Mediastinum Deck (88):
1

Define Mediastinum

Region of thorax located between the two pleural sacs and extends from the thoracic inlet to the diaphragm

2

What are the anterior and posterior bounds of the mediastinum

Anterior- sternum and costal cartilages.

Posterior- Bodies of thoracic vertebrae

3

What are the primary two divisions of the mediastinum

superior and inferior portions

4

What are the 3 subdivisions of the inferior mediastinum

anterior, middle, and posterior

5

What are the anterior and posterior boundaries of the anterior mediastinum

Anterior: Anterior surface of the pericardium

Posterior. Posterior surface of the costal cartilages and posterior surface of sternum

6

What does the middle portion of the mediastinum contain

Heart and pericardium

7

What does the posterior portion of the mediastinum contain

Posterior surface of pericardium, and anterior surface of vertebral bodies T5-T12

8

Vertebral levels of the superior mediastinum

T1-T4

9

Anterior and Posterior bounds of superior mediastinum

Posterior surface of manubrium and anterior surface of thoracic vertebrae T1-T4

10

List of structures in the anterior mediastinum

thymus gland, internal thoracic a.

11

What is the role of the thymus gland in the child, what happens as the individual ages

Makes antibodies, the gland in the aging individual no longer functions and turns to fat.

12

Where is the thymus gland located within the anterior mediastinum

between the two braciocephalic veins

13

At the 6th rib what does the internal thoracic a. break into

Musculophrenic a. and superior epigastric a,

14

What does the musculophrenic a. supply

diaphragm

15

what does the superior epigastric a. supply

rectus sheath

16

What is the internal thoracic a. a branch of?

Subclavian a.

17

What are two other arterial branches given off by the internal thoracic a.

anterior intercostal a- supply intercostal spaces

Periocariacophrenic a- supplies phrenic n.

18

Constriction of the aorta will result in rib notching due to what anastomose?

Internal thoracic and intercostal a.

19

What is the most anterior structure of superior mediastinum

thymus

20

For the ducts, arteries, and veins in the superior mediastinum, which are most anterior and posterior?

Veins- anterior
Arteries- intermediate
Ducts (trachea esophagus, thoracic duct)- Posterior

21

What structure in the superior mediastinum is as far lateral as possible

phrenic n.

22

Is the left recurrent laryngeal n. a part of the superior mediastinum? What about the right

Yes, the right however is not because it is in the root of the neck

23

Branches coming off the superior vena cava in the superior mediastinum

left and right brachiocephalic vein

24

Branches coming of the arch of the aorta in the superior mediastinum

Descending aorta, brachiocephalic a., left common coratid a. and Left subclavian a.

25

In the superior mediastinum, what direction are the veins and arteries directed?

Veins- right and arteries-left because the venous portion of the heart is to the left and the opposite is true for the arterial portion

26

What are the two branches off the brachiocephalic veins

Subclavian v. and internal jugular v.

27

How does Superior vena cava syndrome arise

Results from obstruction of the superior vena cava

28

What is a common cause of superior vena cava syndrome

Enlargement of lymph nodes from cancer

29

What are symptoms of superior vena cava syndrome

Redness to face and upper extremities due to the back up of blood from superior vena cava which dilates capillaries

30

What organ is present in both the superior and anterior mediastinum

thymus

31

What are the two portions of the aorta

Ascending and desending

32

At what point does the ascending aorta start to descend posteriorly

At the sternal angle

33

What does the descending aorta come into contact with

Trachea and esophagus

34

What would a lesion of the aorta also likely involve?

Trachea and esophagus because they are in contact with one another

35

What is the most common anomaly when it comes to branching off of the aorta

The vertebral artery may instead of coming off the subclavian will come off between the left common coratid a. and left subclavian a.

36

What is the only branch of the brachiocephalic a. that is in the superior mediastinum

thyroidea ima

37

what does the thyroidea ima supply?

Thyroid gland

38

What are the two branches of the brachiocephalic a.

right subclavian a and right common coratid a.

39

At way point does the right brachiocephalic a divide into the right subclavian a. and right common coratid a.

Posterior to the sternoclavicular joint

40

What part of the mediastinum contains the descending aorta?

Posterior

41

What is the point of bifurcation of the trachea called?

Carina

42

Where is the carina located

Sternal angle

43

In what lung are aspirated objects more likely to enter and why

Right lung because the right mainstream bronchus is wider and more vertical than the left.

44

Are primary bronchi in the superior mediastinum

no

45

Is the esophagus posterior or anterior to the trachea

posterior

46

Where does the thoracic duct begin

in the abdomen opposite SMA at the upper end of the cistern chyli

47

What are the regions of the body not drained by the thoracic duct?

The right upper extremity, right chest, right neck, and right side of face

48

What does the lymph from the thoracic duct drain into

the juncture between the left internal jugular v. and left subclavian v.

49

What drains the lymph from the right upper extremity, right thorax, right head and neck?

Right lymphatic duct

50

Where does the right lymphatic duct drain into the venous system

At the junction of the right subclavian and right internal jugular v.

51

Do the phrenic nerves descend into the superior mediastinum

Yes (From C3,4,5)

52

How can someones vocal cords be paralyzed?

By damaging the left recurrent laryngeal n (comes off vagus)

53

What nerve forms a plexus around the trachea

Vagus

54

Where does the left recurrent laryngeal n. course

around the left side of the ligament arteriosum under the arch of the aorta

55

Are the left and right recurrent laryngeal nerves present in the superior mediastinum?

Left yes right no. The right is at the root of the neck and loops between the esophagus and trachea

56

Since the left recurrent laryngeal n. is located in the anterior mediastinum (lots of lymph nodes) what are they prone to?

Paralysis of vocal cords caused by pinching the l. recurrent laryngeal n. from enlarged lymph nodes

57

What is another way the left recurrent laryngeal branch may be compromised?

aortic aneurism (the thoracic aorta is prone to these)

58

What are the two plexi that the left vagus nerve contributes to

The esophageal and cardiac autonomic plexus

59

Are the paired sympathetic chains also located in the superior mediastinum?

Yes

60

What are the contents of the posterior mediastinum

esophagus (with its vagal plexi), descending aorta, thoracic duct, azygos/hemiazygos/accessory azygos veins, and splanchnic nerves

61

Where are the 3 regions where the esophagus narrows

1. Its origin
2. at its midpoint where it is constricted by the aortic arch and left mainstream bronchus
3. Inferiorly where it passes through the diaphragm

62

Where does the azygous vein lie?

To the right side of the vertebral column

63

Where does the azygous empty into

Superior vena cava

64

Which intercostal spaces are directly drained by the azygous vein

5-12

65

How is blood from intercostal spaces (2-4) indirectly drained into the azygous v.

Blood drains into the right superior intercostal vein, which empires into the azygous v.

66

Where does the hemiazygous v. begin?

At level of diaphragm

67

What intercostal spaces does the hemiazygous drain

8-12

68

Where does the accessory hemiazygous begin and end

Intercostal space T4-T7

69

Where is the thoracic duct positioned?

Between the azygous v. and the aorta

70

What are the 3 branches the descending aorta gives off

1. Paired posterior intercostal a.
2. bronchiol arteries
3. Esophageal arteries

71

Why is the sympathetic chain present in the superior mediastinum but not the posterior mediastinum and the splanchnic n. are located in the posterior, which come off of the sympathetic chain?

Because as you travel down, the chain mosts posterior to the vertebral bodies (thus moving out of the mediastinum since the posterior border of the mediastinum is the anterior surface of the vertebral bodies)

72

To review: What are all of the components of the anterior mediastinum

Thymus and internal thoracic a.

73

To review: What are all of the components of the superior mediastinum

-Left and right brachiocephalic veins
-Ascending and arch of aorta
-Branches: Left brachiocephalic a., Left common coratid a., and left subclavian a.
-Thoracic duct, esophagus, trachea

74

What vessels are located in the root of the neck

-Branches off of the left and right brachiocephalic veins: Subclavian v. and internal jugular v.
-Branches off left brachiocephalic a.: Right Subclavian a. and right common coratid a.

75

What are the structures in the posterior mediastinum

esophagus (with its vagal plexi), descending aorta, thoracic duct, azygos/hemiazygos/accessory azygos veins, and splanchnic nerves

76

Describe the location of the thymus

Sits between the two brachiocephalic v.

77

Describe the location of the internal thoracic a.

Run with the phrenic n and pericardiophrenic a. and v.

78

In the superior mediastinum, what is the arrangement for the three different ducts (thoracic, trachea, and esophagus)

Trachea (inferior to descending aorta), esophagus, thoracic duct

79

What vessels coming off of the aorta are most anterior? Most posterior?

Goes in alpha-order from anterior to posterior: Left brachiocephalic, left common coratid, and left subclavian

80

In the posterior mediastinum, where is the azygous v. located

Right side of vertebral column deep to the esophagus

81

Where is the thoracic duct

Sandwiched between the descending aorta and azygous v.

82

From what intercostal spaces do the two hemiazygous veins run?

Accessory hemiazygous- T4-T7
Hemiazygous- T5-12

83

What do the accessory and hemiazygous veins drain into?

Azygous

84

What are the 3 vessels the descending aorta gives off in the abdomen posterior to the diaphragm

1. paired posterior intercostal a
2. bronchial a.
3. esophageal a.

85

Splanchnic nerves

Run from sympathetic chain towards the anterior vertebral column

86

List all the structures found in more than one segment of the mediastinum

-Aorta
-Thoracic duct
-Esophagus
-Vagus n
-Phrenic n.

87

What is related to the esophagus as it passes through the thorax

aorta, main stem (or primary bronchus), and the pericardium

88

Why can the phrenic n. be damaged during coronary bypass surgery

Because the phrenic nerve in the anterior mediastinum is glued to the heart