T1 L2: Superior mediastinum

Question 1

Where is the division between the superior and inferior mediastinum?

Answer 1

At level T4/5 (the sternal angle or the transverse thoracic plane)

Question 2

At what level does the trachea bifurcate?

Answer 2

Level T4/5

Question 3

What structures are in the inferior anterior mediastinum?

Answer 3

None, it’s the space between the sternum and the heart

Question 4

What structures are part of the inferior middle mediastinum?

Answer 4

The heart and the pericardium

Question 5

What structures are part of the inferior posterior mediastinum?

Answer 5

Everything that isn’t in the inferior anterior or middle mediastinum

Question 6

What is in the superior boundary of the superior mediastinum?

Answer 6

Superior thoracic aperture (connective tissue between the thorax and neck)

Question 7

What is the inferior boundary of the superior mediastinum?

Answer 7

The transverse thoracic plane (T4/5)

Question 8

What is the anterior boundary of the superior mediastinum?

Answer 8

The manubrium

Question 9

What is the posterior boundary of the superior mediastinum?

Answer 9

T1-T4/5 vertebral bodies

Question 10

What is the lateral boundary of the superior mediastinum?

Answer 10

The mediastinal pleura

Question 11

What is the main function of the thymus gland?

Answer 11

T cells mature in the thymus

Question 12

What 3 nodes drain the lymph from the thymus gland?

Answer 12

Parasternal, brachiocephalic and tracheobronchial nodes

Question 13

Where are parasternal lymph nodes?

Answer 13

Either side of the sternum

Question 14

Where are the brachiocephalic lymph nodes?

Answer 14

Near the brachiocephalic vein

Question 15

Where are tracheobronchial lymph nodes?

Answer 15

At the hilum

Question 16

What is the thymus gland replaced by after puberty?

Answer 16

By fat

Question 17

What are the 3 branches of the arch of the aorta?

Answer 17

1. Bronchiocephalic trunk
2. Left common carotid artery
3. Left subclavian artery

Question 18

What arteries does the bronchiocephalic trunk branch off into?

Answer 18

The right subclavian artery (blood to right upper limbs) and the right common carotid artery (blood to the neck, head and brain)

Question 19

What is the clinical importance of Virchow’s node?

Answer 19

It can indicate abdominal cancer but can sometimes be benign

Question 20

What are the 2 branches of the ascending aorta?

Answer 20

The left and right coronary arteries

Question 21

What are the 3 branches of the descending aorta?

Answer 21

The posterior intercostals, bronchial arteries and lumbar arteries

Question 22

When do the left and right coronary arteries fill up?

Answer 22

Between ventricular contractions (during a contraction, blood is pushed up the arch of the aorta but some of it will fall back down and pool at the bottom of the closed aortic valve. This blood flows into the coronary arteries)

Question 23

What are the different branches of the superior vena cava?

Answer 23

Firstly into the left and right brachiocephalic veins. Then each side bifurcates into a subclavian and internal jugular vein.

Question 24

What is the ligamentum arteriosum?

Answer 24

It’s the embryological remnant of the ductus arteriosus (a duct connecting the pulmonary trunk and the arch of the aorta to allow the blood to bypass the immature lungs)

Question 25

What is the trachealis muscle?

Answer 25

The muscle on the posterior trachea that allow food to pass down through the oesophagus

Question 26

What is the longest lymphatic vessel in the body?

Answer 26

The thoracic duct

Question 27

What is the thoracic duct?

Answer 27

Numerous lymph nodes associated with the descending (thoracic) duct

Question 28

What are the origins of the phrenic nerve?

Answer 28

From the anterior rami of spinal nerves C3, C4 and C5.

Question 29

What is the function of the phrenic nerve?

Answer 29

Motor supply to the diaphragm and sensory supply to the diaphragmatic and mediastinal pleura

Question 30

Between what vessels does the phrenic nerve enter the superior mediastinum?

Answer 30

Between the brachiocephalic veins and subclavian arteries

Question 31

How does the phrenic nerve pass the main bronchi?

Answer 31

Anteriorly

Question 32

What is CNX?

Answer 32

Cranial nerve 10 (the Vagus nerve)

Question 33

How does the Vagus nerve enter the superior mediastinum?

Answer 33

Between the brachiocephalic veins and subclavian arteries medially to the phrenic nerve

Question 34

What is the recurrent laryngeal branch of the Vagus nerve?

Answer 34

The loop of the Vagus nerve that goes on to supply the larynx

Question 35

How does the Vagus nerve pass the main bronchi?

Answer 35

Posteriorly

Question 36

What is the function of the Vagus nerve?

Answer 36

Provides parasympathetic supply via the pulmonary, cardiac and oesophageal plexi

Question 37

What is the first stage of cardiac development?

Answer 37

Angiogenic clusters form in the mesoderm and then canalise to form early blood vessels. 2 heart tubes form and pair up at about day 21

Question 38

Why must the heart be one of the first major system to begin functioning in an embryo?

Answer 38

Because diffusion is lo longer efficient as the embryo gets bigger

Question 39

What day of development does the heart usually begin to beat?

Answer 39

Day 22-23

Question 40

What are Truncus arteriosus?

Answer 40

The primitive outflow vessels

Question 41

What are Sinus Venosus?

Answer 41

The primitive inflow vessels

Question 42

Why does the heart start to fold at day 23?

Answer 42

Because it gets too long for the pericardial cavity

Question 43

What are the 4 divisions of a newly formed heart tube before folding?

Answer 43

Sinus Venosus, primordial atrium, primordial ventricle and Truncus arteriosus

Question 44

What are the 2 cardiac features that allow the blood to bypass the lungs?

Answer 44

The foreman ovale and ductus arteriosus. Some blood must still reach the lungs to allow them to develop

Question 45

How does blood reach the foeutus?

Answer 45

Through the umbilical vein

Question 46

What is the foreman ovale?

Answer 46

The hole in the atrial septum that allows blood to go straight to the left atria an not the lungs

Question 47

What is the ductus arteriosus?

Answer 47

Its a tube that connects the pulmonary trunk to the arch of the aorta. Most of the blood from the pulmonary trunk will travel through it and then to the rest of the body instead of the lungs

Question 48

Describe the development of the foreman ovale

Answer 48

1. An incomplete septum primum forms with an ostium primum 2. An ostium secondum forms when the primum fuses 3. The incomplete septum secundrum forms (the foreman ovale)

Question 49

What is the ostium primum?

Answer 49

The incomplete part of the septum primum in the development of the foreman ovale

Question 50

What is an interseptal defect?

Answer 50

It's a hole in the heart that remains when the foreman ovale doesn't fuse. (Normally as the foetus develops, the pressure between the atria evens out so the foreman ovale fuses)

Question 51

How does blood flow through the the foreman ovale?

Answer 51

There is a high pressure in the right atrium because no blood is leaving through the pulmonary veins so blood travels down the pressure gradient