Development of Aortic Arches

FATE OF AORTIC ARCHES

Identify the structures labelled 1-10.

Q. What are aortic arches and how many are there?

A. Aortic arches are the arteries of pharyngeal arches that arise from aortic sac and terminate into dorsal aorta on each side. Initially 6 aortic arches appear, but 5th aortic arch soon disappears.

Q. What is the fate of aortic arches?

A.  The following diagram shows the fate of aortic arches:

Q. What is the fate of 1st and 2nd aortic arches?

A.   Most of the 1st aortic arch disappears, small remaining part contributes to maxillary artery.  most of the 2nd aortic arch also disappears, the remaining part forms hyoid and stapedial artery.

Q. What are the derivatives of 3rd aortic arch?

A.  Following arteries are formed from 3rd aortic arch:

• Proximal part forms common carotid artery.
• Distal part along with cranial part of dorsal aorta forms internal carotid artery.
• External carotid artery arises as a sprout of 3rd aortic arch.

Q. What are the derivatives of 4th aortic arch?

A. The derivatives of 4th aortic arch are different on right and left side.

• On  the right side it forms  proximal part of right subclavian artery (the distal part of right subclavian is formed by right dorsal aorta and 7th cervical intersegmental artery).
• On  the left side it forms part of arch of aorta.

Q. What are the derivatives of 6th aortic arch?

A.  Following are the derivatives of 6th aortic arch:

• On the right side – the proximal part of right 6th aortic arch forms right pulmonary artery and the distal part degenerates.
• On the left side – The proximal part of left aortic arch forms left pulmonary artery and the distal part forms ductus arteriosus ( connection between the left pulmonary artery and aorta). after birth, ductus arteriosus is obliterated and forms ligamentum arteriosum).