Thorax 3 - superior mediastinum

Question 1

At which level do IVC, aorta and oesophagus go through diaphragm?

Answer 1

Aorta T12
IVC T8
Oes T10

Question 2

What are the divisions of the mediastinum?

Answer 2

Superior - above sternal angle
Inferior

Middle
Anterior
Posterior

Question 3

What is the ligementum arteriosum?

Answer 3

Old fetal circulation that bypasses lungs as they are not functional in foetus
between pulmonary artery and aorta

Question 4

From which nerve is the phrenic nerve formed?

Answer 4

C3,4,5 keeps the diaphragm alive

Question 5

How are the vagus and phrenic nerve positioned in relation to great arteries?

Answer 5

• Vagus nerves lateral to common carotids
• Left vagus passes anterior to aortic arch
• Left phrenic crosses vagus to cross aortic arch more anteriorly

Question 6

Describe the left phrenic and vagus nerves

Answer 6

• Cross arch of aorta
• Left phrenic descends in front of root lung
• Left vagus crosses behind root lung gives off left recurrent laryngeal nerve – recurs (=turns back) around ligamentum arteriosum and aortic arch – lower than the right
• Breaks up into many branches round oesophagus

Question 7

Describe the right vagus nerve

Answer 7

• Lies on the trachea
• Crosses behind the root lung
• Recurrent laryngeal branch – recurs (turns back) around right subclavian artery
• Breaks up into branches on oesophagus