6. Superior and Posterior Mediastinum

Question 1

What are the borders of the superior mediastinum?

Answer 1

Superior - thoracic inlet
Anterior - manubrium
Inferior - transverse thoracic plane
Posterior - bodies of T1-T4 vertebrae

Question 2

What are the contents of the superior mediastinum?

Answer 2

Thymus
Bracheocephalic veins and SVC
Arch of aorta
Trachea
Oesophagus
Vagus nerves
Phrenic nerves

Question 3

What vessels come off the arch of aorta?

Answer 3

Bracheocephalic trunks (divides into R subclavian artery and R common carotid artery)
L common carotid artery
L subclavian artery

Question 4

At what vertebral level does the trachea begin?

Answer 4

C6/C7

Question 5

What is the function of the trachealis muscle posterior to the tracheal wall?

Answer 5

Soft tissue allows accommodation for expansion of oesophagus

Question 6

At what vertebral level does the oesophagus begin?

Answer 6

C6 (continuation of pharynx)

Question 7

Nerve roots of phrenic nerve?

Answer 7

C3 C4 C5 (keeps the diaphragm alive)

Question 8

At what vertebral level is the oesophageal hiatus? (i.e. where does the oesophagus pierce the diaphragm)

Answer 8

T10

Question 9

What are the 3 constrictions of the oesophagus?

Answer 9

Arch of aorta
Left bronchus
Diaphragm

Question 10

Where do the R and L recurrent laryngeal nerves loop under?

Answer 10

R - under R subclavian artery

L - under arch of aorta

Question 11

What structures are found in the posterior mediastinum?

Answer 11

DATES

Descending aorta
Azygos system
Thoracic duct
oEsophagus
Sympathetic nerves (splanchic nerves)

Question 12

Borders of posterior mediastinum?

Answer 12

Superior - transverse thoracic plane
Anterior - pericardium
Inferior - diaphragm
Posterior - bodies of T5 - T12 vertebrae

Question 13

At what level does the arch of aorta become the thoracic aorta?

Answer 13

T4/T5

Question 14

When does the thoracic aorta become the abdominal aorta?

Answer 14

After passing through hiatus of diaphragm - T12

Question 15

On the R side, into what veins do the posterior intercostal veins drain?

Answer 15

1st posterior intercostal –> R bracheocephalic vein

2nd - 11th + subcostal –> Azygos vein

Question 16

On the L side, into what veins do the posterior intercostal veins drain?

Answer 16

1st - 4th posterior intercostal –> L bracheocephalic vein
5th - 8th –> accessory hemiazygos vein
9th - 11th + subcostal –> hemiazygos vein

Question 17

Where does the thoracic duct empty into the venous system?

Answer 17

Junction of L internal jugular and L subclavian veins (L VENOUS ANGLE)

Question 18

At what levels is the sympathetic outflow?

Answer 18

T1 - L2/L3

Question 19

What plexus do the R and L vagus nerves form?

Answer 19

Oesophageal plexus

Question 20

What group of nerves provide sympathetic innervation to abdominopelvic organs?

Answer 20

Greater splanchnic
Lesser splanchnic
Least splanchnic

Question 21

Which sympathetic ganglia levels does the greater splanchnic nerve come from?

Answer 21

T5 - T9

Question 22

Which sympathetic ganglia levels does the lesser splanchnic nerve come from?

Answer 22

T10, T11

Question 23

Which sympathetic ganglia levels does the least splanchnic nerve come from?

Answer 23

T12

Question 24

With what does the greater splanchnic nerve synapse?

Answer 24

Pre-aortic ganglion - coeliac or superior mesenteric ganglion

Question 25

With what does the lesser splanchnic nerve synapse?

Answer 25

Pre-aortic ganglion - superior mesenteric or aorticorenal

Question 26

With what does the least splanchnic nerve synapse?

Answer 26

Pre-aortic ganglion - aorticorenal ganglion