HS2-18 Mediastinum

Question 1

What is the definition of the mediastinum?

Answer 1

central part of chest between pleural cavities

Question 2

What is the superior border of the mediastinum?

Answer 2

thoracic inlet

Question 3

What is the inferior border of the mediastinum?

Answer 3

diaphragm

Question 4

What is the lateral border of the mediastinum?

Answer 4

pleural cavity (on both sides)

Question 5

What is the anterior border of the mediastinum?

Answer 5

sternum/thoracic wall

Question 6

What is the posterior border of the mediastinum?

Answer 6

vertebral column

Question 7

What structure defines the the aortic arch?

Answer 7

the transthoracic plane — intersects ascending and descending aorta

Question 8

What structure does the transthoracic plane intersect in the thorax?

Answer 8

trachea

Question 9

What are the boundaries of the transthoracis plane?

Answer 9

runs from sternal angle (anterior) to IV disc between T4/T5 (posterior)

Question 10

What are the four compartments of the mediastinum?

Answer 10

superior

anterior

middle

posterior

Question 11

The middle mediastinum is bordered by

Answer 11

the pericardium

Question 12

Give an example of a mediastinal mass.

Answer 12

thymoma (originating from residual thymus/thymic tissue)

Question 13

What are the borders of the superior mediastinum?

Answer 13

superior = thoracic inlet

inferior = transthoracic plane

Question 14

What gland is found in the superior mediastinum?

Answer 14

thymus gland

Question 15

What veins are found in the superior mediastinum?

Answer 15

superior vena cava

brachiocephalic veins

azygos vein

hemiazygos vein

posterior intercostal veins

Question 16

What is the fate of the thymus gland?

Answer 16

disintegrates after puberty and gets replaced with fat

Question 17

The brachiocephalic veins drain

Answer 17

the subclavian and internal jugular veins

Question 18

How can you differentiate between the left and right brachiocephalic veins?

Answer 18

left is longer and more obliquely oriented than right

Question 19

Where is the azygos vein found?

Answer 19

right side of vertebral bodies, posterior to right main bronchus

Question 20

The azygos vein drains into

Answer 20

the superior vena cava

Question 21

The hemiazygos vein is found where?

Answer 21

left side of vertebral bodies

Question 22

The hemiazygos vein drains into

Answer 22

the azygos vein

Question 23

The posterior intercostal veins drain into

Answer 23

the azygos vein (right side)

the hemiazygos vein (left side)

Question 24

What are the three branches that come off the arch of the aorta?

Answer 24

brachiocephalic artery/trunk

left common carotid artery

left subclavian artery

Question 25

How does the brachiocephalic artery/trunk further branch after coming off the aortic arch? (2)

Answer 25

branches into right common carotid artery + right subclavian artery

[therefore, brachiocephalic artery itself is in mediastinum, but its branches are not]

Question 26

What nervous structure(s) is/are found in the superior mediastinum?

Answer 26

vagus nerve (CN X)

Question 27

How can you differentiate between the right vagus nerve and left vagus nerve?

Answer 27

right vagus nerve = runs between right brachiocephalic vein + brachiocephalic trunk

left vagus nerve = runs underneath left brachiocephalic vein and underneath aortic arch

Question 28

Differentiate between the right and left recurrent laryngeal nerves in the context of the mediastinum.

Answer 28

right recurrent laryngeal nerve does not reach mediastinum

left recurrent laryngeal nerve loops around arch of aorta to “recur” to larynx

Question 29

How does the esophagus exit the thorax?

Answer 29

through esophageal hiatus in diaphragm

Question 30

What is the anterior border of the anterior mediastinum?

Answer 30

sternum/thoracic wall

Question 31

What is the posterior border of the anterior mediastinum?

Answer 31

pericardium

Question 32

What is the superior border of the anterior mediastinum?

Answer 32

transthoracic plane

Question 33

What are the contents of the middle mediastinum? (3)

Answer 33

heart

roots of great vessels

phrenic nerves

Question 34

What is the superior border of the posterior mediastinum?

Answer 34

transthoracic plane

Question 35

What is the anterior border of the posterior mediastinum? (2)

Answer 35

pericardium

diaphragm

Question 36

What is the posterior border of the posterior mediastinum?

Answer 36

bodies of T5-T12

Question 37

What are the contents of the posterior mediastinum? (6)

Answer 37

vagus nerve

thoracic splanchic nerves

descending aorta

azygos system

thoracic duct

esophagus

[three-and-a-half-geese and a duck]

Question 38

The esophageal plexus is derived from

Answer 38

the vagus nerve

Question 39

Differentiate between the anterior and posterior vagal trunk.

Answer 39

anterior vagal trunk = derived from left vagus

posterior vagal trunk = derived from right vagus

Question 40

The thoracic splanchic nerves branch from

Answer 40

the sympathetic trunks, and run anteriorly to the vertebral bodies

Question 41

(T/F) Sympathetic trunks are considered to be a part of the mediastinum.

Answer 41

False. By definition, they’re not considered to be in the mediastinum because they are lateral to the vertebral bodies

Question 42

Draw a diagram of the branches of the descending aorta in the posterior mediastinum.

Answer 42

Question 43

In which mediastinal compartment are no nerves found?

Answer 43

anterior mediastinum