Embryology Heart Glossary

Question 1

What is the bulbus cordis?

Answer 1

Superior part of the heart tube. Caudal end forms the smooth part of the ventricles and the cranial end forms the truncus arteriosus

Question 2

Is there an adult remnant of the bulbus cordis?

Answer 2

No

Question 3

What is the cardiac jelly?

Answer 3

Gelatinous extracellular matrix that helps regulate migration, proliferation and differentiation. Also plays role in development of the valves and septa of the heart. Separates myocardium and heart tube.

Question 4

Is cardiac jelly present in adults?

Answer 4

No

Question 5

What is cardiac looping?

Answer 5

Bending of the heart tube positions the heart in the left thoracic region and creates the “typical” heart shape with the atria posterior to the ventricles.

Question 6

What are the crista terminalis?

Answer 6

Ridge of tissue in the right atrium between the trabeculated part of the right atrium and the smooth-walled part derived from the sinus venosus.

Question 7

What are the endocardial tubes?

Answer 7

Paired tubes of the embryo formed by angioblasts. Folding of the embryo brings the tubes into closer proximity and they fuse to form the primitive heart tube.

Question 8

What are endocardial tubes formed by?

Answer 8

Angioblasts

Question 9

What do endocardial tubes fuse to form? What brings them closer together to fuse?

Answer 9

Craniocaudal folding

Fuse to form the primitive heart tube

Question 10

What is the endocardium?

Answer 10

Inner endothelial layer of the heart derived from the heart tube

Question 11

Where is the endocardium derived from?

Answer 11

The heart tube

Question 12

What is the epicardium?

Answer 12

Outer layer of the heart also known as the visceral layer of the pericardium. It is derived from the visceral mesoderm. Forms the coronary arteries

Question 13

What is the epicardium derived from?

Answer 13

The visceral mesoderm

Question 14

What does the epicardium go on to form?

Answer 14

The coronary arteries

Answer 15

Question 16

What is purpose of the foramen ovale?

Answer 16

Allows blood to flow from the right atrium into the left atrium, bypassing the right ventricle and lungs

Question 17

What is the remnants of the foramen ovale after birth?

Answer 17

Septum primum and secundum fuse to form the fossa ovalis (depression found on interatrial septum in the right ventricle)

Question 18

What is the foramen primum?

Answer 18

Gap in the septum primum where blood can pass between the common atria. Becomes obliterated as the foramen secundum forms superiorly on the septum primum

Question 19

Is the foramen primum present in adults?

Answer 19

No

Question 20

What is the foramen secundum?

Answer 20

Opening that forms in the upper part of the septum primum by apoptosis as the foramen primum becomes obliterated

Question 21

What is the myocardium?

Answer 21

Middle contractile layer of the heart derived from the visceral mesoderm overlying the heart tube

Question 22

What is the primitive atrium?

Answer 22

A dilation of the developing heart tube that forms from the roughened wall of the atrial wall formed by the pectinate muscles

Question 23

What is the primitive ventricle?

Answer 23

A dilation of the developing heart tube that goes on to form the roughened majority of the ventricle –> trabeculae carnae

Question 24

What are the endocardial cushsions?

Answer 24

Structures consisting of loose connective tissue covered by endothelium that are responsible for most septation processes occuring in the heart, particularly between the atria and ventricles

Question 25

What is the conus arteriosus?

Answer 25

A swelling near the cranial end of the developing heart tube. Goes on to form the smooth parts of the ventricle just before the pulmonary trunk and aorta

Question 26

What are the smooth parts of the ventricle just before the pulmonary trunk called?

Answer 26

The conus arteriosus

Question 27

What are the smooth parts of the ventricle just before the aorta called?

Answer 27

Aortic vestibule

Question 28

What is the septum primum?

Answer 28

First septum to grow down from the roof of the common atrium and contributes to the interatrial septum

Question 29

What is the septum secundum?

Answer 29

Second septum to grown down from the roof of the common atrium towards the atrioventricular endocardial cushions. An oblique opening (foramen ovale) is created between the septum secundum and septum primum that allows the shunting of blood from the right to left atrium during fetal development.

Question 30

What happens to the opening between the septum secundum and septum primum after birth?

Answer 30

Opening is closed when septum primum is pressed against the septum secundum and the adult pattern of blood flow is established

Question 31

What is the sinus venosus?

Answer 31

Caudal end of the developing heart tube that largely degenerates by week 5. The right horn goes on to form the smooth part of the right atrial wall (sinus venarum). The left horn forms the oblique vein of the left atrium and coronary sinus.

Question 32

What is the truncus arteriosus?

Answer 32

Common arterial outflow at the cranial end. It is septated by the conotruncal septum to form the pulmonary trunk and aorta

Question 33

What is the ductus arteriosus?

Answer 33

A patent vessel in foetal circulation between the pulmonary trunk and aorta. A shunt in fetal circulatory system so blood can bypass the lungs. Closes shortly after birth to form the ligamentum arteriosum.

Question 34

What is the conotruncal septum?

Answer 34

Formed by conotruncal swellings in the truncus arteriosus. The septum forms in spiral formation. Contains neural crest cells. Separates the common outflow tube to the aorta and the pulmonary trunk