1) The first arteries to develop in the embryo are the primitive aortae, consisting of the ventral aorta, first aortic arch, and dorsal aorta. 2) The aortic arches arise from the aortic sac and terminate in the dorsal aorta. The first two pairs of arches usually disappear, while the third, fourth, and sixth pairs form important adult structures. 3) Derivatives of the third arch include the common and internal carotid arteries. Derivatives of the fourth arch include parts of the aortic arch and subclavian arteries. Derivatives of the sixth arch include the pulmonary arteries.

1. The Aortic Arches
S. B. Rauniyar
5/2/2016

2. Embryonic Blood Vessels
• By the beginning of the 4th week, an extensive network of
blood vessels is formed throughout the embryonic body
• The heart begins to beat on 21st or 22nd day, and blood
begins to circulate.
• This makes the CVS to be the first system in the body to
reach the functional state
• The embryonic heartbeat can be detected ultrasono-
graphically during the 5th week

4. Aortic Arches

5. Aortic Arches
• 1st arteries to appear is primitive aortae consist of
 a portion lying ventral to foregut( ventral aorta) ,
 an arched portion (1st aortic arch) , &
 dorsal portion lying dorsal to the gut ( dorsal aorta)
• The ventral aorta partially fuse to form aortic sac , unfused
part remaining as the right & left horn of aortic sac.
• The aortic arches arise from the aortic sac and terminate in
the dorsal aorta of the ipsilateral side

6. Aortic Arches
• Though six pairs of aortic arches usually develop
• All are not present at the same time
• By the time the sixth pair of aortic arches has formed,
the first two pairs disappear
• During the eighth week, the aortic arch pattern is
transformed to final fetal arterial arrangement
• In the region of aortic arches, the dorsal aortae
remain paired, but caudal to this region they fuse to
form a single median vessel

7. Changes in the original aortic arch system

8. Changes in the original aortic arch system
• Obliteration of:
 Most of the 1st & 2nd arches
 5th arches completely
 Distal part of the right sixth arch
 The segment of both dorsal aortae lying between the
3rd & 4th arches ( ductus caroticus )
 The segment of right aorta lying between the 7th
intersegmental artery & the fused dorsal aortae

9. Derivatives of Aortic Arches

10. First Pair
• Largely disappear
• Dorsal part persists as
the maxillary arteries
which supply the ear,
teeth and muscles of
the eyes and face
• May give rise to the
external carotid artery
The first arch is obliterated before
the 6th arch is formed

11. Second Pair
• Largely disappear
• Dorsal part persists
as the hyoid and
stapedial arteries

12. Third Pair
• Proximal part:
forms the
common carotid
arteries
• Distal part: joins
the dorsal aortae
to form the
internal carotid
arteries

13. Third Pair
• Each third arch artery
gives off a bud that
grows cranially to
form the External
carotid artery

14. Fifth Pair
• Disappears
completely
with NO
vascular
derivatives

15. The fate of 4 & 6th pairs of aortic
arches differs on the right and left side

16. Aortic sac
• Aortic sac & left
horn : becomes the
proximal segment
of the Aortic arch
• Right horn :
becomes the
Brachiocephalic
artery

17. Fourth Pair
• RIGHT: Becomes
the proximal part
of the right
subclavian artery
• LEFT: Forms part
of the arch of
aorta

18. Arch of Aorta
Derived as:
• Proximal segment from
aortic sac
• Middle segment from
the left horn of aortic
sac
• Distal segment from the
left 4th aortic arch

19. Subclavian Artery
• The right subclavian
artery formed from
the:
 Right horn of aortic
sac &
 Right 4th aortic arch
 Right 7th
intersegmental
artery
• The left subclavian
artery formed from the
left 7th intersegmental
artery

20. Sixth Pair
• RIGHT:
:- Proximal part: persists as the
proximal part of the right
pulmonary artery
:- Distal part: degenerates
• LEFT:
:- Proximal part: persists as the
proximal part of the left
pulmonary artery
:- Distal part: forms ductus
arteriosus, a shunt between
pulmonary artery and dorsal
aorta

22. ADULT DERIVATIVES OF FETAL VESSELS
 Umbilical vein becomes the ligamentum teres hepatis.
Umbilical arteries( rt &lt) :--
• proximal part superior vesicle arteries
• distal part  medial umbilical ligaments. .
 Ductus venosus  ligamentum venosum,
Foramen ovale  fossa ovalis
Ductus arteriosus  ligamentum arteriosum

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Anomalies of Aortic Arches
Patent ductus arteriosus

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Coarctation of aorta
Types

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Abnormal origin of right subclavian artery:
Types

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Double aortic arch

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Right aortic arch

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Interrupted aortic arch

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Persistent ductus caroticus