Embryology

Question 1

What do the first and second aortic arches become?

Answer 1

The first and second arches disappear early. A remnant of the 1st arch forms part of the maxillary artery. The external carotid buds from the horns of the aortic sac left behind by the regression of the first two arches.

Question 2

What does the third aortic arch become?

Answer 2

Commencement of the internal carotid artery

It contributes to the common carotid artery and the proximal portion of the internal carotid artery

Question 3

What does the fourth aortic arch become?

Answer 3

Right subclavian as far as the origin of its internal mammary branch.
Arch of the aorta between the origin of the left carotid artery and the termination of the ductus arteriosus.

Question 4

What does the fifth aortic arch become?

Answer 4

The fifth arch regresses or forms incompletely.

Question 5

What does the sixth aortic arch become?

Answer 5

The proximal part of the sixth right arch persists as the proximal part of the right pulmonary artery while the distal section degenerates; The sixth left arch gives off the left pulmonary artery and forms the ductus arteriosus.