Thorax 4 - Mediastinum

Question 1

Where is the mediastinum found in the heart?

Answer 1

The area between the two pleural cavities.

Question 2

What does the superior part of the mediastinum go up to?

Answer 2

The 2nd rib

Question 3

What forms the anterior, middle and posterior mediastinum?

Answer 3

Anterior - between the sternum and the pericardium.
Middle - pericardium and its contents
Posterior - behind the pericardium, anterior to T5 and T12

Question 4

What does the posterior mediastinum contain?

Answer 4

The descending aorta 
Thoracic duct
Azygos vein system
Oesophagus 
Sympathetic chain

The descending aorta, trachea and oesophagus lie anterior to the azygos vein system and the thoracic duct.

Question 5

What are the main things inside the superior mediastinum?

Answer 5

• Aortic arch and its 3 branches
• Brachiocephalic veins
• Sympathetic chain
• Vagus nerves
• Phrenic nerves
• Trachea
• Oesophagus
• Thoracic duct
• Lymph nodes

Question 6

What are the names of the 3 branches that come off the aorta?

Answer 6

Brachiocephalic trunk
Left common carotid
Left subclavian artery

Question 7

What do brachiocephalic veins come together to form?

Answer 7

The superior vena cava

Question 8

What part of the spinal cord does the sympathetic chain come from?
Phrenic nerves?

Answer 8

T1 - L2

C3-C5

Question 9

Explain where the vagus nerve comes from and what it forms at the heart?

Answer 9

It comes from the brain stem (cervical part of the spinal cord). At the aorta, it forms a cardiac plexus which is important in parasympathetic autonomic control of the heart.

Question 10

What does the thoracic duct do?

Answer 10

Biggest lymphatic duct draining the lymph back into the venous circulation.

Question 11

What does the bronchial artery come off and what does it do?

Answer 11

the aorta, it supplies the lungs with blood

Question 12

Where does the descending aorta emerge?

Answer 12

Behind the diaphragm at T12

Question 13

What does the right subclavian artery split into?

Answer 13

The anterior intercostal muscles and an internal thoracic artery

Question 14

What does the pericardiophrenic artery supply?

Answer 14

Blood to the pericardium

Question 15

Where does the oesophagus pass through the diaphragm?

Answer 15

T10

Question 16

What is the azygos system?

Answer 16

Lies posterior to the descending aorta, trachea and oesophagus.
The posterior intercostal muscles drain into this system, the veins merge to form accessory veins.
They drain upwards and form the superior vena cava.

Question 17

Give details on the thoracic duct

Answer 17

• Collects lymph from the intestines and lower limbs
• runs superiorly between the oesophagus and the descending aorta
• crosses from right to left at T4/5, lying between the azygos vein and aorta
• empties into the venous system at the point where the left internal jugular and subclavian veins meet

Question 18

What is the role of the phrenic nerves?

Answer 18

To keep the diaphragm alive

Question 19

Where does the intercostal nerve come from?

Answer 19

It is from the ventral ramus of the spinal cord

Question 20

Explain how the sympathetic nerves leave the spinal cord

Answer 20

They leave via the ventral horn and synapse within the sympathetic chain (a chain of nerves with their ganglia - collection of cell bodies). They have short preganglionic ganglia because they come out the central horn and synapse immediately.

Question 21

What is the function of the sympathetic chain in the heart and lungs?

Answer 21

Heart - increases rate and contractility

Lung - vasocontriction and bronchiodilation

Question 22

Explain how the vagus nerve is positoned in the body

Answer 22

It comes out the brain stem and innervates the aorta. It has a branch which innervates the larynx.

Question 23

Where are the phrenic nerve and vagus nerve positioned in terms of the lungs?

Answer 23

Phrenic nerve is infront and the vagus nerve goes behind

Question 24

Does the vena cava pass through the muscular or tendon part of the diaphragm?

Answer 24

It passes through the vena cava foramen which is located in the central tendon of T8.