Lecture 8 RH

Question 1

What is the mediastinum?

Answer 1

Mediastinum is an area in the thoracic cage in the center of the thoracic cavity. It contains the space between the lungs.

Question 2

What are the sections of the mediastinum? What separates them?

Answer 2

superior mediastinum

inferior mediastinum

They are separated by the plane of louis. (At the manubriosternal joint)

Question 3

What happens at the plane of louis and what are some structures present nearby?

Answer 3

between T4 and T5

It is the point where the great vessels leave the heart.

It is the point where the Main bronchi bifurcate.

Question 4

What are the postero anterior sections of the mediastinum?

Answer 4

heart is at the middle mediastinum.

Anteriorly is the thoracic cage and the pericardium.

Posteriorly is the descending aorta and all the structures behind the heart directly.

Question 5

Where is the thymus located?

Answer 5

immediately deep to the manubrium is the thymus..

Question 6

what is the function of the thymus?

Answer 6

Thymus is important for the development of the immune system. It is lost during puberty due to redundancy.

Question 7

What are the branches of the superior vena cava?

Answer 7

Superior vena cava forms 2 branches; the right and left brachiocephalic veins.

Question 8

What are the branches of the left and right brachiocephalic veins?

Answer 8

right brachiocephalic vein forms the right subclavian and right internal jugular vein.

Left does the same with left subclavian and internal jugular.

Question 9

What are the branches of the aortic arch?

Answer 9

Brachiocephalic artery to the right.

Left common carotid

Left subclavian artery

Question 10

What does the aorta arch over?

Answer 10

Posteriorly to the left over the left pulmonary trunk and the left main bronchus before descending into the posterior inferior mediastinum.

Question 11

What is the purpose of the brachiocephalic trunk?

Answer 11

forms a bridge between the aortic arch and the right subclavian + right common carotid.

Question 12

What are the first branches of the aorta?

Answer 12

The coronary arteries.

Question 13

What are the main nerves that innervate the heart?

Answer 13

Right and left vagus nerves

Right and left phrenic nerves

Right and left recurring laryngeal nerves. (these nerves come of the vagus nerves and curl under the left side of the aortic arch and goes back up to the larynx)

Question 14

What is the purpose of the recurrant laryngeal nerves?

Answer 14

For phonation

Question 15

What structure is the left recurrant laryngeal nerve really close to?

Answer 15

The ligamentum artereosum.

Question 16

What is the clinical significance of the location of the left recurrant (recurrent you daft cunt) laryngeal nerve?

Answer 16

Cardiosurgeons repairing a patent ductus artereosus could potentially accidentally constrict the nerve causing phonation problems.

Question 17

What are the structures found in the superior mediastinum?

Answer 17

oesophagus

trachea

Thoracic duct (drains lymph from below diaphragm into the left brachiocephalic vein)

Question 18

Where does the thoracic duct drain into?

Answer 18

Brachiocephalic vein

Question 19

What can be found in the anterior mediastinum?

Answer 19

Fat

Lymph nodes

Internal thoracic vessels

Inferior part of thymus (in children)

Question 20

What can be found in the middle mediastinum?

Answer 20

Superior vena cava

Phrenic nerve

Heart

Pulmonary trunk

Ascending aorta

Question 21

What structures can be found in the posterior mediastinum?

Answer 21

Thoracic duct

Right and left vagus nerve (running behind the main bronchi)

oesophagus (moves off towards the left)

descending thoracic aorta

Question 22

Where is the descending aorta relative to the oesophagus in the posterior mediastinum?

Answer 22

lateral and posterior.(remember that aorta goes behind the diaphragm whereas the oesophagus goes through muscular part of the diaphragm right crus slings around the oesophagus to form functional sphincter)

Question 23

Where does the thoracic duct run within the mediastinum?

Answer 23

Directly anterior to the vertebra and posteriorly to the aorta. (this structure is very hard to find)

Question 24

What level does the aorta pierce the diaphragm?

Answer 24

T12

Question 25

What structures does the descending aorta supply?

Answer 25

descending aorta supplies most abdominal viscera and the thoracic walls. It gives off the posterior intercostal arteries which anastomose with anterior intercostal arteries derived from the internal thoracic arteries. Bronchial arteries supply non-respiratory parts of the lungs and bronchi. They are derived from descending aorta oesophagus is supplied directly by the oesophageal branches of the descending aorta.

Question 26

Where are anterior intercostal arteries derived from?

Answer 26

From the internal thoracic arteries

Question 27

Where are the internal thoracic arteries derived from?

Answer 27

From the subclavian arteries.

Question 28

What is the function of bronchial arteries?

Answer 28

bronchial arteries supply non-respiratory parts of the lungs and bronchi. They are derived from descending aorta

Question 29

Where does the oesophagus derive its blood supply?

Answer 29

oesophagus is supplied directly by the oesophageal branches of the descending aorta.

Question 30

What are the layers of the oesophagus?

Answer 30

3 layers of muscle; circular, longitudinal, then circular.

Question 31

What is the shape of the oesophageal tube?

Answer 31

oesophagus is flattened in an anteroposterior direction.

Question 32

What veins drain the oesophagus?

Answer 32

The azygous system of veins.

Question 33

What nerves supply the oesophagus?

Answer 33

Sympathetic nerves vagus sends branches in for parasympathetic innervation. Autonomous nervous system form mixture of nerves known as plexuses.

Question 34

What is the path that the thoracic duct takes in?

Answer 34

Thoracic duct as it ascends at around plane of louie it moves off to the left side and descends to the left brachiocephalic vein.

Question 35

What does the thoracic duct drain?

Answer 35

Below the diaphragm and the left upper limb.

Question 36

What is the cysterna chyli?

Answer 36

A swollen structure that appears in the thoracic duct in rare cases.

Question 37

How do the lungs drain into the thoracic duct?

Answer 37

lymphatic drainage of the left lung drains via the bronchomediastinal trunk into the left thoracic duct. Right lung goes into right lymphatic duct into the right brachiocephalic vein. This right lymphatic duct drains the right upper limb as well.

Question 38

Where does the right lymphatic duct drain?

Answer 38

The right upper limb and right lung.

Question 39

What is the function of the azygous system?

Answer 39

azygous veins are on posterior wall of thorax and they drain the whole thorax and return it into the superior vena cava

Question 40

What side does the azygous vein run along?

Answer 40

The right of the vertebral column it loops around the right main bronchus.

Question 41

What do the intercostal veins drain into?

Answer 41

upper posterior drain into accessory azygous veins Lower posterior intercostal veins drain into the hemizygous vein.

Question 42

What do the accessory and hemiazygous veins drain into?

Answer 42

into the azygous veins. (at about T9 lots of variability)

Question 43

What can be said about the variability of the azygous vein?

Answer 43

Huge variability in the way the azygous system looks.

Question 44

Where can the azygous vein drain into to reach the heart?

Answer 44

azygous vein can communicate at the inferior vena cava below the level of the diaphragm. It loops around the right main bronchus into the superior vena cava.