Embryology Flashcards
(27 cards)
Which germ layer is the heart derived from?
The visceral mesoderm
Where does the primary heart field start to develop?
Cranial to the neural plate
How does embryonic folding bring the heart tube to its final position?
- Lateral folding brings the heart tube from the lateral borders to the midline of the embryo
- Cranio-caudal folding brings the heart tube from the cranial end of the embryo to the middle
Name the regions of the heart tube, moving from cranial to caudal
- Truncus arteriosus
- Bulbus cordis
- Ventricle
- Atrium
- Sinus venosus
What does each region of the heart tube become in the adult heart?
- Truncus arteriosus
- Bulbus cordis
- Ventricle
- Atrium
- Sinus venosus
- Truncus arteriosus: proximal aorta, pulmonary trunk
- Bulbus cordis: right ventricle, outflow parts of both ventricles
- Ventricle: left ventricle
- Atrium: both atria
- Sinus venosus: smooth part of right atrium, coronary sinus
Around day 23, the heart tube starts to loop and fold. Describe the main movements of the atrium, ventricle and bulbus cordis
Atrium: dorsal + cranial
Ventricle: left
Bulbus cordis: inferior + ventral + right
How many aortic arches are there?
6
Which aortic arches regress?
1, 2 and 5
What do the 3rd aortic arches become?
Common carotid arteries and the first part of the internal carotid arteries
(bilateral)
What do the 4th aortic arches become?
Right - right subclavian artery
Left - part of the aortic arch proper
(asymmetric)
What do the 6th aortic branches become?
The pulmonary arteries and ductus arteriosus
What are the 3 different venous systems within the embryo?
Vitelline
Umbilical
Systemic
What do the vitelline veins do in the embryo?
Drain the yolk sac
What do the vitelline veins become in the adult?
- Portal venous system
- Hepatic sinusoids and veins in the liver
- Portion of the IVC associated with the liver
What do the umbilical veins do in the embryo?
Carry oxygen rich blood from the mother via the placenta
Why do the umbilical veins join with the vitelline veins?
Because the liver is taking up most of the abdominal cavity so they need a way to reach the sinus venosus
Which umbilical vein regresses?
The right umbilical vein
What is the ductus venosus?
A large vein that forms in the liver so that blood from the remaining left umbilical vein can travel directly to the heart
When does the left umbilical vein regress?
When it is clamped at birth
What is the name of the remnant of the umbilical vein?
The ligamentum teres
What does the ductus venosus become in the adult once it is no longer required?
The ligamentum venosum
In the embryo, what is the systemic venous system composed of?
The anterior and posterior cardinal veins
What do the anterior and posterior cardinal veins do?
Anterior cardinal veins: drain the head and neck
Posterior cardinal veins: drain the trunk
Where do all of the venous systems drain back into?
The sinus venosus
