SUPERIOR MEDIASTINUM

Question 1

Boundaries of superior mediastinum and their location

Answer 1

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

Question 2

Contents of superior mediastinum

Answer 2

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

Question 3

Location of thymus

Answer 3

beneath sternum - in superior and anterior mediastinum

Question 4

Thymus in children

Answer 4

functional

Question 5

Thymus in adults

Answer 5

involution

Question 6

Brachiocephalic veins are formed by the union of

Answer 6

internal jugular and subclavian veins

Question 7

L and R brachiocephalic veins join to from the

Answer 7

SVC

Question 8

L brachiocephalic vein course and location

Answer 8

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

Question 9

L brachiocephalic vein tributaries

Answer 9

IJV, subclavian, internal thoracic vein, thoracic duct

Question 10

R brachiocephalic vein course and location

Answer 10

short vertical course – lateral to brachiocephalic artery

Question 11

R brachiocephalic vein tributaries

Answer 11

IJV, subclavian, Internal thoracic vein, R lymphatic duct

Question 12

What tributaries differ between R and L brachiocephalic veins?

Answer 12

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

Question 13

SVC is formed by the union of

Answer 13

R and L brachiocephalic veins

Question 14

SVC ends at

Answer 14

R atrium

Question 15

What structures are anterior to SVC?

Answer 15

portion of R lung + associated pleura

Question 16

What structures are posterior to SVC?

Answer 16

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

Question 17

What structures are medial to SVC?

Answer 17

Ascending aorta

Question 18

What structures are lateral to SVC?

Answer 18

R phrenic nerve

Question 19

What is the major clinical correlate of the SVC?

Answer 19

SVC Syndrome

Question 20

SVC Syndrome

Answer 20

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)

Question 21

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

Answer 21

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

Question 22

What veins drain into the SVC?

Answer 22

veins from arm/head/neck

Question 23

4 parts of the aorta

Answer 23

Ascending, Arch, Descending Thoracic, and Abdominal

Question 24

What type of vessel is the aorta?

Answer 24

strong, high-pressure vessel

Question 25

Where does the Ascending aorta start and end?

Answer 25

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

Question 26

Branches of ascending aorta

Answer 26

L and R coronary arteries

Question 27

What structure is lateral to the ascending aorta?

Answer 27

SVC

Question 28

Where does the aortic arch start and end?

Answer 28

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

Question 29

Branches of the aortic arch

Answer 29

brachiocephalic, L common carotid, L subclavian arteries

Question 30

What structures are anterior to the aortic arch?

Answer 30

L Vagus and phrenic nerves + L recurrent laryngeal nerve

Question 31

What structures are posterior to the aortic arch?

Answer 31

trachea/bifurcation, esophagus

Question 32

What is the main clinical correlate to the aorta?

Answer 32

aortic aneurysm

Question 33

Aortic Aneurysm

Answer 33

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

Question 34

Outcome of aortic aneurysm in the ascending portion of the aorta

Answer 34

compression of SVC

Question 35

outcome of aortic aneurysm in the aortic arch

Answer 35

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

Question 36

What nerve supplies the vocal cord?

Answer 36

laryngeal nerve

Question 37

Brachiocephalic aortic branch becomes ________ at _____

Answer 37

becomes R common carotid and subclavian arteries at sternoclavicular joint

Question 38

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

Answer 38

L brachiocephalic vein

Question 39

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

Answer 39

trachea

Question 40

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

Answer 40

L brachiocephalic vein

Question 41

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

Answer 41

trachea and L recurrent laryngeal nerve

Question 42

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

Answer 42

L vagus nerve and L phrenic nerve

Question 43

L subclavian branch of aortic arch runs ____ and exits ____

Answer 43

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

Question 44

Vagus nerve is located in the

Answer 44

mediastinum

Question 45

Vagus nerve gives rise to

Answer 45

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

Question 46

R vagus nerve travels

Answer 46

posterior to SVC

Question 47

R vagus nerves gives ____ at _______

Answer 47

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

Question 48

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

Answer 48

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

Question 49

L vagus nerve gives _____ at _____

Answer 49

Gives L recurrent laryngeal nerve branch at aortic arch

Question 50

Phrenic nerve innervates what vertebrae?

Answer 50

C3, C4, C5

Question 51

Phrenic nerve innervates the

Answer 51

diaphragm

Question 52

Phrenic nerve originates in the

Answer 52

diaphragm

Question 53

R phrenic nerve runs

Answer 53

lateral to SVC, then along pericardium

Question 54

L phrenic nerve runs

Answer 54

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

Question 55

Trachea is made of

Answer 55

fibrocartilage

Question 56

What vertebral levels does the trachea start and end at?

Answer 56

C6 to T4/T5 disc

Question 57

What structures are anterior to the trachea?

Answer 57

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

Question 58

What structures are posterior to the trachea?

Answer 58

esophagus

Question 59

What structures are on the R side of the trachea?

Answer 59

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

Question 60

What structures are on the L side of the trachea?

Answer 60

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

Question 61

Where does lymphatic drainage of the trachea occur?

Answer 61

pre and para-tracheal lymph node