Dr Rania Gabr
 Describe
the formation of the aortic arches.
 Enlist the derivatives of aortic arches.
 Discuss the development of venous system of
the heart.
 Differentiate between fetal and neonatal
circulation.
 Discuss the congenital anomalies of the
aortic arches.
Aortic Arches
 During 4th and 5th weeks of development, aortic
arches arise from aortic sac
 During
folding:
 The primitive aorta is
divided into 3
segments:
1) Ventral aorta
2) First aortic arch
3) Dorsal aorta
The 2 ventral aortae fuse
to form the heart tube.
Now the heart tube is
connected to the dorsal
aorta by the first aortic
arch on each side.
 The
aortic arches terminate in right and left
dorsal aortae.
 (In the region of the arches the dorsal aortae
remain paired, but caudal to this region they fuse
to form a single vessel.)
Only the vessels on the left side of the embryo
are shown.
Ventral view of the
embryo

The aortic aches appear in a cranial to caudal
sequence gradually.

The aortic sac gives rise to a total of six pairs of
arteries. During further development, some vessels
regress completely.
The fifth pair is
rudimentary and
disappears at a very
early stage
aortic sac
A. Aortic arches and dorsal aortae before
transformation into the definitive
vascular pattern.
Arch
I:
By day 27, most of 1st aortic
arch has disappeared on
both sides, a small portion
persists to form maxillary
artery.
Arch
II:
 2nd
aortic arch soon
disappears.
 The
remaining portions are
hyoid and stapedial
arteries.
Arch
III:
CAROTID ARCH
–
Persists becomes part
of carotid arteries.
 1-
Common carotid
artery
 2-Proximal part of
internal carotid artery
 3-External carotid artery
The remainder of internal
carotid artery is formed by
the cranial portion of the
dorsal aorta
Arch IV:
AORTIC ARCH
-Right side: Rt
subclavian
-Left side : Main Part of
the ARCH OF AORTA.
Arch V:
DISAPPEARS
 The
aortic sac then forms right and left
horns, which subsequently give rise to
brachiocephalic artery and proximal
segment of aortic arch, respectively.
B. Aortic arches and dorsal aortae after the transformation. Broken lines, obliterated
components. C. The great arteries in the adult.
Arch VI:
PULMONARY
ARCH –
On the left side:
Ventral part: Left
pulmonary artery
Dorsal part : Ductus
arteriosus
On the rt side:
Ventral part: Right
Pulmonary artery
Dorsal part: Disappears
( No ductus arteriosus on
the right side)
 The
left recurrent laryngeal
nerve, recurs on the ductus
arteriosus.
 Absence of the ductus on the
rt side allows the rt recurrent
laryngeal nerve to recur on
the rt subclavian artery
 Persistence
of the Ductus
arteriosus and later
Ligamentum arteriosum is the
cause of presence of the left
recurrent laryngeal nerve in
the thorax , while the rt
remains in the neck due to
absence of ductus on the rt
side.
A number of other changes occur:
 (a) dorsal aorta between entrance of 3rd and 4th arches,
known as carotid duct, is obliterated.

(b) right dorsal aorta disappears between origin of the
7th intersegmental artery and junction with the left
dorsal aorta.
So , the Arch of Aorta
develops from 3 parts:
 1)
Proximal part : from
the left part of the
aortic sac
 2) Middle part: from
the left 4th aortic arch
 3) Distal Part: From the
dorsal aorta between
the left fourth and 6th
arches
Vitelline Arteries
 vitelline
arteries, supplying yolk sac, gradually
fuse and form arteries in dorsal mesentery of gut,
celiac, superior mesenteric, and inferior
mesenteric arteries.
 These vessels supply derivatives of foregut,
midgut, and hindgut respectively.
Umbilical arteries



The umbilical arteries are paired ventral branches of dorsal
aorta
During the 4th week, each artery acquires a secondary
connection with dorsal branch of aorta, common iliac artery,
and loses its earliest origin.
After birth the proximal portions of umbilical arteries persist
as internal iliac and superior vesical arteries, and distal
parts are obliterated to form medial umbilical ligaments.
CLINICAL CORRELATES---Arterial System Defects
 Under
normal conditions the ductus
arteriosus is functionally closed through
contraction of its muscular wall shortly
after birth to form the ligamentum
arteriosum.

A patent ductus arteriosus either may be
an isolated abnormality or may
accompany other heart defects.
Coarctation
 It
of aorta
is a Local narrowing of
the lumen of the aorta
just distal to the origin of
the Left Subclavian
Artery ,above or below
the entrance of ductus
arteriosus.
 2 types:
 In preductal type, ductus
arteriosus persists
 In postductal type,
ductus arteriosus is
obliterated.
 Double
aortic arch
 Right dorsal aorta persists between origin of 7th
intersegmental artery and its junction with left
dorsal aorta.
 A vascular ring surrounds the trachea and esophagus
and commonly compresses these structures, causing
difficulties in breathing and swallowing.
7th intersegmental
artery
 In
a 4 weeks embryo, three
paired veins open into the
tubular heart:
 Vitelline veins, returning
deoxygenated blood from
the yolk sac
 Umbilical veins, bringing
oxygenated blood from the
placenta.
 Common cardinal veins,
returning deoxygenated
blood from the body of the
embryo

Pass through the septum transversum and
drain into the sinus venosus

In relation to the liver developing within
the septum transversum, the vitelline
veins are divided into:

Pre-hapatic part: forms anastomosis
around the duodenum which later on
gives rise to the portal vein

Hepatic part: interrupted by the liver
cords, forms an extensive vascular
network called the hepatic sinusoides

Post-hepatic part:

Left vein disappears

Right vein forms the:

Hepatic veins &

Hepatic segment of inferior vena
cava
 Bring
oxygenated blood
from the placenta
 Initially run on each side
of the developing liver
and drain into the sinus
venosus
 As the liver grows, the
umbilical veins loose
their connection with
heart and open into the
liver
 The right vein
disappears by the end of
the embryonic period.
The left vein persists
A
wide channel, the
ductus venosus, appears
through the substance of
liver to connect the left
umbilical vein with the
inferior vena cava
After birth:
- The left
umbilical vein
obliterates to
form the
ligamentum teres
of the liver
- The ductus
venosus
obliterate to form
the ligamentum
venosum
 Are
responsible to drain the
body of the embryo
 The cranial part of the
embryo is drained by
paired anterior cardinal
veins
 The caudal part of the
embryo is drained by
paired posterior cardinal
veins
 The anterior & posterior
cardinal veins join to form
common cardinal veins,
which drain into the sinus
venosus
 Become
connected by an
oblique anastomosis which
shunts blood from left to
right
 This anastomosing channel
becomes the left
brachiocephalic vein
 Left anterior cardinal vein
 Cranial part: becomes the
left internal jugular vein
 Caudal part: degenerates
 Right
anterior cardinal vein
 Cranial part: (cranial to
the 7th intersegmental
vein) becomes the right
internal jugular vein
 Middle part: gives rise to
the right brachiocephalic
vein
 Caudal part of right
anterior cardinal vein and
the right common cardinal
vein form the superior
vena cava
 Drain
the caudal part of
the body of embryo
including the developing
mesonephros and largely
disappear with this
transitory kidneys.
 Caudally the two veins get
connected by an
anastomosing channel that
directs the blood from the
left to the right vein
 Gradually
the
posterior
cardinal veins
are replaced
by two new
veins:
subcardinal &
supracardinal
The adult
derivatives of the
posterior cardinal
veins are the:
 Root of the
azygos vein &
 Common iliac
veins
 SVC
is derived from
the:
 Caudal
part of
the right anterior
cardinal vein
&
 Right common
cardinal vein
 Azygos
vein is derived
from the:
 Cranial part of the right
supracardinal vein &
 Terminal part of the right
posterior cardinal vein
 Hemiazygos vein is derived
from the cranial part of
the left supra-cardinal
vein
The IVC develops during a
series of changes in the
primordial veins
 Composed of:
 Hepatic segment derived
from the right vitelline vein
 Prerenal segment derived
from the right subcardinal
vein
 Renal segment derived from
the subcardinalsupracardinal anastomosis
 Postrenal segment derived
from the right supracardinal
vein

 By
the third month of development, all
major blood vessels are present and
functioning.
 Fetus
must have blood flow to placenta.
 Resistance
to blood flow is high in the lungs.
 Pair
of umbilical
arteries carry
deoxygenated
blood & wastes to
placenta.
 Umbilical vein
carries oxygenated
blood and
nutrients from the
placenta.
 Some
blood from the
umbilical vein enters the
portal circulation
allowing the liver to
process nutrients.
 The majority of the
blood enters the ductus
venosus, a shunt which
bypasses the liver and
puts blood into the
hepatic veins .Then to
Inferior vena cava
 Blood
is shunted from
right atrium to left
atrium, skipping the
lungs.
 More than one-third
of blood takes this
route.
 Is a valve with two
flaps that prevent
back-flow.
 The
blood pumped
from the right
ventricle enters the
pulmonary trunk.
 Most of this blood is
shunted into the
aortic arch through
the ductus
arteriousus.
The change from fetal to postnatal circulation
happens very quickly.
 Changes are initiated by baby’s first breath.

Foramen ovale
Ductus venosus
Closes shortly after birth,
fuses completely in first
year.
Closes soon after birth,
becomes ligamentum
arteriousum in about 3
months.
Ligamentum venosum
Umbilical arteries
Medial umbilical ligaments
Umbilical vein
Ligamentum teres
Ductus arteriousus