Lecture 2: Superior mediastinum

Question 1

What is the division between the superior and inferior mediastinum?

Answer 1

Transverse thoracic plane

Level of the sternal angle - junction of vertebrae T4/5

Question 2

What are the three divisions of the inferior mediastinum?

Answer 2

Anterior
Middle
Posterior

Question 3

What is the superior limit of the superior mediastinum?

Answer 3

The superior thoracic aperture - manubrium, 1st rib and costal cartilage, T1 vertebra

Question 4

What is the anterior boundary of the superior mediastinum?

Answer 4

Manubrium

Question 5

What is the posterior boundary of the superior mediastinum?

Answer 5

T1-T4/5 vertebral bodies

Question 6

What is the lateral boundary of the superior mediastinum?

Answer 6

Mediastinal pleura

Question 7

What is in the superior mediastinum?

Answer 7

Arteries (arch of aorta and branches)

Veins (brachiocephalic veins, superior vena cava)

Trachea

Oesophagus

Thoracic duct

Phrenic and Vagus nerves

Thymus gland (part)

Question 8

Where is the thymus gland?

Answer 8

Located immediately deep to the sternum in Superior AND Anterior Mediastinum

Question 9

What is the thymus gland?

Answer 9

Lymphoid organ

T and B lymphocytes are produced in bone marrow.

Bs mature in bone marrow, Ts mature in Thymus.

Question 10

What is the blood supply of the thymus?

Answer 10

Internal thoracic arteries

Question 11

What replaces the thymus gland when it atrophies at puberty?

Answer 11

Fat

Question 12

Where does lymph drain from the thymus gland?

Answer 12

Through from parasternal, brachiocephalic and tracheobronchial nodes

Question 13

What are the three branches of the aortic arch?

Answer 13

Brachiocephalic trunk
Left common carotid artery
Left subclavian artery

Question 14

Which vessel branches into the right common carotid & right Subclavian arteries?

Answer 14

The brachiocephalic trunk

Question 15

What are the 1st arteries branching from the ascending aorta?

Answer 15

Left & right coronary arteries

Question 16

What branches from the descending aorta?

Answer 16

Intercostal, bronchial & lumbar arteries

Question 17

What % of people have the normal pattern of aortic branching?

Answer 17

65%

Question 18

Which two veins come together to form the superior vena cava?

Answer 18

Left and right brachiocephalic veins

Question 19

Which two veins come together to form the brachiocephalic veins?

Answer 19

An internal jugular vein and a subclavian vein

Question 20

What drains into the venous angle?

Answer 20

Lymph

Question 21

What artery runs along with the internal jugular?

Answer 21

The common carotid

Question 22

What is the name of the structure that becomes the ligamentum arteriorsum?

Answer 22

Ductus arteriosus

Question 23

What two structures are connected by the ligamentum arteriosum?

Answer 23

The pulmonary trunk and the arch of the aorta

Question 24

What is the purpose of the ductus arteriosus?

Answer 24

Important in foetal circulation allowing blood to bypass the immature lungs

Question 25

After birth, the ductus arteriosus closes and becomes what?

Answer 25

The ligamentum arteriosum

Question 26

Where does the oesophagus run from and to?

Answer 26

Pharynx to stomach

Question 27

Where does the trachea run from and to?

Answer 27

Larynx to bronchi

Question 28

Where do the phrenic nerve originate from?

Answer 28

C3, C4 and C5

Question 29

Where do the phrenic nerves enter the superior mediastinum?

Answer 29

Between the brachiocephalic veins and the subclavian arteries

Question 30

Do the phrenic nerves run anterior or posterior to the main bronchi?

Answer 30

Anterior

Question 31

What structures do the phrenic nerves provide motor and sensory supply to?

Answer 31

Motor - diaphragm Sensory - diaphragm and pleura (diaphragmatic and mediastinal)

Question 32

How many phrenic nerves are there?

Answer 32

2

Question 33

Where do the vagus nerves originate?

Answer 33

CNX - brainstem

Question 34

Where do the vagus nerves enter the superior mediastinum?

Answer 34

Close to but medial to the phrenic nerve

Question 35

How many vagus nerves are there?

Answer 35

2

Question 36

What branches from the vagus nerves?

Answer 36

Recurrent laryngeal nerves to supply the larynx

Question 37

Do the vagus nerves travel anterior or posterior to the main bronchi?

Answer 37

Posterior

Question 38

What type of supply do the vagus nerves provide?

Answer 38

Parasympathetic supply via pulmonary, cardiac and oesophageal plexi

Question 39

What is present in the anterior mediastinum?

Answer 39

Thymus gland/fatty tissue Pericardial-sternal ligaments Lymph nodes and vessels Internal thoracic artery

Question 40

What are the boundaries of the anterior mediastinum?

Answer 40

Sternum anteriorly Pericardial sac posteriorly Diaphragm inferiorly

Question 41

What layer do the angiogenic clusters form from?

Answer 41

Mesoderm

Question 42

What are the two large blood vessels called that form in the cardiogenic area?

Answer 42

Heart tubes

Question 43

By which day does the single heart tube begin to fold?

Answer 43

Day 23

Question 44

Which chambers are anterior and posterior?

Answer 44

Anterior - ventricles | Posterior - atria

Question 45

What is the name of the primitive outflow vessel?

Answer 45

Truncus arteriosus

Question 46

What is the name of the primitive inflow vessel?

Answer 46

Sinus venosus

Question 47

What are the two features of the foetal heart that allow blood to bypass the lungs?

Answer 47

Foramen ovale Ductus arteriosus

Question 48

What is the foramen ovale?

Answer 48

Opening between the right and left atria in the foetus and allows oxygenated blood to by-pass lungs

Question 49

When the foramen ovale closes, what does it become?

Answer 49

Fossa ovalis

Question 50

Where is the fossa ovals located in the adult heart?

Answer 50

In the inter-atrial septum