A: Mediastinum spots

Question 1

When ligating the ductus arteriosus, what structure immediately behind it must be identified so that it is not damaged?

Answer 1

Left recurrent laryngeal nerve

Question 2

Within which division of the mediastinum is the aortic arch located? What is its surface marking?

Answer 2

• Superior mediastinum
• Behind the manubrium of sternum
  (Note: aortic arch starts and finishes at the level of the sternal angle)

Question 3

Answer 3

Left coronary artery

Question 4

Describe the surface markings of left brachiocephalic vein. Why is it more vulnerable to injury in the child?

Answer 4

• Crosses midline from left to right, posterior to manubrium of sternum
• In child, rises above upper border of manubrium –> less protected from injury

Question 5

What is the distribution of phrenic nerve?

Answer 5

• Motor to diaphragm
• Sensory to central parts of diaphragm, fibrous pericardium and parietal layer of serous pericardium

Question 6

Describe course of azygos vein

Answer 6

• Arises in abdomen
• Passes through aortic opening in diaphragm to enter posterior mediastinum
• Runs upward along right side of vertebral bodies
• Receives right posterior intercostal veins
• Forms on arch over root of right lung
• Enters SVC

Question 7

Outline the course of the hemiazygos vein from where it commences.

Answer 7

• Arises in abdomen
• Passes through aortic opening in diaphragm to enter posterior mediastinum
• Runs upward along left side of vertebral bodies
• Receives left posterior intercostal veins
• Crosses over to right side, posterior to thoracic aorta
• Empties into azygos vein

Question 8

Which chamber of the heart lies immediately anterior to the oesophagus?

Answer 8

Left atrium

Question 9

What type of nerve fibers are found within vagus nerve?

Answer 9

Parasympathetic fibres and visceral afferent fibres

Question 10

Answer 10

• Posterior intercostal vein

Question 11

What is the relationship of the phrenic nerves to the aortic arch and superior vena cava?

Answer 11

Left phrenic n: just lateral to aortic arch
Right phrenic n: just lateral to superior vena cava

Question 12

A sudden deceleration (e.g. road traffic accident) may cause injury to the aorta at certain locations. List these locations.

Answer 12

Aortic valve, attachment of ligamentum arteriosum, as it passes through the diaphragm.
(Note: these are locations where the aorta is relatively fixed in position)

Question 13

Describe the surface markings of SVC

Answer 13

• Lateral to sternum
• Between lower borders of 1st and 3rd right costal cartilage

Question 14

What type of nerve fibres are carried in the thoracic splanchnic nerves (i.e. greater, lesser and least splanchnic nerves)?

Answer 14

• Preganglionic sympathetic fibres
• Visceral afferent fibres from abdomen