Thorax 6 - Development of Heart and Great Vessels

Question 1

By what day in embryonic development is a heart required to drive circulation?

Answer 1

Day 18

Question 2

From which embryonic layer does the heart originate?

Answer 2

Mesoderm

Question 3

Why is the heart based slightly on the left of the thorax?

Answer 3

The 2 ends fold slightly to the right, bringing the apex of the heart round to the left

Question 4

From which veins does the venous end receive blood?

Answer 4

Cardinal
Vitelle
Umbilical

Question 5

Describe two ways in which narrowing between atria and ventricles ensues.

Answer 5

Kink in the tube during folding of the early heart

Endocardial cushions

Question 6

What does the 1st aortic arch form?

Answer 6

Maxillary arteries

Question 7

What does the 3rd aortic arch form?

Answer 7

Common carotid arteries

Question 8

What does the left 4rd arch form?

Answer 8

Aortic arch

Question 9

What does the right 4th arch form?

Answer 9

Right subclavian artery

Question 10

What does the left 6th arch form?

Answer 10

Pulmonary trunk & ductus arteriosus

Question 11

What does the right 6th arch form?

Answer 11

Contributes to the pulmonary trunk

Question 12

Which nerve can be impinged?

Answer 12

Left recurrent laryngeal nerve

Question 13

The trip-laminar disk forms by week 3. What are the 3 layers?

Answer 13

Ectoderm
Mesoderm
Endoderm

Question 14

How long is the embryo by week 3?

Answer 14

1.5mm

Question 15

What does the heart tube form from and where does it form?

Answer 15

Angiogenetic clusters

Mesoderm

Question 16

When does cephalon-caudal and lateral folding begin?

Answer 16

Day 18

Question 17

When does looping and folding begin?

Answer 17

Day 22

Question 18

How does the heart end up on the left side of the body?

Answer 18

The two ends of the heart tube fold towards each other and slightly to the right. This pushes the apex out to the left and rotates slightly so that the right side of the heart is slightly more anterior

Question 19

During cephalon-caudal folding, what do each of the germ layers contribute?

Answer 19

Ectoderm: visceral pericardium
Mesoderm: cardiac muscle
Endoderm: endothelial lining

Question 20

What is the name given in the case that the heart folds slightly to the left as opposed to the right, pushing the apex right?

Answer 20

Dextrocardia

Question 21

At 28 days, how large is the embryo and what developments have there been with the heart?

Answer 21

5mm
Heart pushes into the pericardial sac
Ventricles begin to trabeculate

Question 22

The venous end receives inflow from which veins?

Answer 22

Cardinal
Umbilical
Vitelle

Question 23

Where do the atria bulge from either side?

Answer 23

Bulbus cordis

Question 24

What do the proximal, middle and distal parts of the bulbus cordis form respectively?

Answer 24

Proximal: RV
Middle: outflow of ventricles
Distal: PT & aorta

Question 25

Why are cranio-facial and cardiac abnormalities commonly linked?

Answer 25

Neural crest cells are involved in both cranio-facial development and cardiac development

Question 26

I cardiac development, what do the neural crest cells form?

Answer 26

Endocardial cushions

Question 27

What do enlargements of the endocardial cushions form?

Answer 27

Interatrial septum Membranous part of the interventricular septum AV valves (tricuspid & mitral) Formation of the PT & Aorta from the truncus arteriosus

Question 28

What structure divides the heart into left and right?

Answer 28

Endocardial cushions

Question 29

What are neural crest cells used to grow?

Answer 29

Septum primum

Question 30

What structure lies underneath the septum primum?

Answer 30

Ostium (foramen) primum

Question 31

Holes developing create an ostium secundum. How are these holes 'filled'?

Answer 31

Formation of a septum secundum to seal the ostium secundum

Question 32

Which side does the septum secundum lie on with regard to the position of the septum primum?

Answer 32

RHS

Question 33

What can atrial septal defect lead to?

Answer 33

Significant shunting from left to right

Question 34

When is the formation of the interventricular septum said to be complete?

Answer 34

End of week 7

Question 35

Where doe left and right ridges of endocardial cushion form?

Answer 35

Conus

Question 36

What is the conotruncal septum?

Answer 36

The result of the left and right tranquil ridges spiralling around each other

Question 37

An extension of which endocardial cushion grows and proliferates to become the muscular portion of the IVS?

Answer 37

Inferior AV cushion

Question 38

What closes the interventricular foramen completely?

Answer 38

Membranous part of the interventricular septum

Question 39

How do the mitral and tricuspid valves, chordae tendinae and papillary muscles form?

Answer 39

Endocardial cushion growth and cavitation

Question 40

How do the aortic and pulmonary valves form?

Answer 40

Hollowing of the endocardial tubercles

Question 41

What is the cause of aortic coarctation?

Answer 41

Abnormality in the aortic media and intimal proliferation

Question 42

In the case of an aortic coarctation, which pulse in particular will be weak upon palpation?

Answer 42

Femoral

Question 43

From which nerve does the recurrent laryngeal originate?

Answer 43

Vagus nerve

Question 44

Which structures does the LRLN hook around?

Answer 44

6th arch Ductus arteriosus / Ligamentum arteriosum IN THORAX

Question 45

Which structures does the RRLN hook around?

Answer 45

4th arch Subclavian artery NOT IN THORAX