1. Development of Superior venacava
and Azygous Vein
Anup Pandey
Dept. of Human Anatomy
B.P. Koirala Institute of Health Sciences
Dharan Nepal

2. Development of Venous system
• In the 5th week, pairs of
major veins can be
seen.
• The main vein of
embryo can be divided
into 2 groups:
a. Visceral veins
b. Somatic veins

3. Visceral and somatic veins.
• Vitelline vein
(omphalomesenteric)-
carrying blood from yolk sac
to sinus venosus.
• Umbilical vein: carry
oxygenated blood to the
embryo.
• Cardinal vein-drains blood
from body wall of the
embryo.

4. Vitelline vein
• arises from capillary
plexus of yolk sac, run in
each side of duodenum
& forms anastomosis
around it.
• with development of
liver, proximal part of
vitelline and umbilical
vein are broken into
numerous channel –
sinusoid –drain into
sinus venosus through
rt. and left hepato -
cardiac channels.

5. • Lt horn of sinus venosus
retrogress and then Lt
hepatocardiac channel
also disappear.
• Blood from umbilical and
vitelline vein now enter
sinus venosus through Rt
hepatocardiac channel
(common hepatic vein)

6. How the portal vein is formed??

7. Development of portal vein
The part of Rt and Lt vitelline
vein lying outside the liver
undergoes changes –
forms portal vein.
It is formed by:
• The lt vitelline vein
between entry of superior
mesentric and splenic vein.
• The dorsal anastomosis.
• Rt vitelline vein between
dorsal anastomosis and
cranial ventral
anastomosis.

8. Umbilical veins
• convey oxygenated
blood from placenta to
the embryo.
• Initially the umbilical
veins pass on each side
of liver.
• proximal part of both
umbilical vein &
remainder of the right
umbilical vein
disappear.

9. • Only left umbilical vein is left
which carries blood from
placenta to liver.
• In order to facilitate blood
supply some sinusoid enlarge
to create direct passage
connecting it with the Rt
hepatocardiac channel–
ductus venosus.
• After birth, left umbilical vein
& ductus venosus are
obliterated to form
ligamentum teres hepatis &
ligamentum venosum
respectively.

10. Cardinal veins
Consists of:
• Anterior cardinal
• Posterior cardinal
• Common cardinal vein

11. • During 5th to 7th wk
additional veins are formed:
1. Subcardinal veins- formed in
relation to the mesonephros,
which drain kidneys.
2. Sacrocardinal veins-drain
lower extremities
3. Supracardinal veins-Drains
the body wall by way of
intercostal veins.
There is anastomosis
between right & left system
so that blood is channeled
from left to right.

12. Cardinal veins
• Form the main venous
drainage system of the
embryo.
 consists of :
• anterior cardinal veins,
which drain the cephalic
part of the embryo,
• posterior cardinal veins,
which drain the rest of the
embryo.
• The anterior and posterior
veins join before entering
the sinus venosus and form
the short common cardinal
veins.

13. Fate of ant. and common cardinal vein
• Superior venacava is
derived from-Rt.
common cardinal vein &
the rt. ant. cardinal
caudal to the transverse
anastomosis.
• Rt. brachiocephalic
vein develops from Rt.
anterior cardinal vein
cranial to the transverse
anastomosis.

14. • Left brachiocephalic
vein: develops from part
of the left ant. cardinal
vein and transverse
intercardinal
anastomosis.
• Internal jugular vein:
develops from the parts
of the ant. cardinal veins
cranial to their junction
with the subclavian
veins.

15. • External jugular veins:
arise as a secondary
channel and are derived
from the venous plexus
in the face.
• Subclavian vein: formed
by considerable
enlargement of the
intersegmental veins in
the region of upper limb
bud.

16. • Lt horn of sinus venosus
retrogress and these veins
persist into adult life as Lt
superior Intercostal vein
and coronary sinus.
• Lt superior intercostal vein
is formed by:
−Left ant.cardinal vein caudal
to the transverse
anastomosis and most
cranial part of the left
posterior cardinal vein.
−The 2nd and 3rd intercostal
vein drain into it.

17. • Coronary sinus
− Medial part is derived
from- left horn of
sinus venosus .
− Lateral part is derived
from - proximal part
of the left common
cardinal vein.
The remaining part of
the left common
cardinal vein persists
as the oblique vein of
left atrium.

18. Clinical correlates
 Venous system defects:
• Left superior venacava: due
to the persistence of the left
anterior cardinal vein, and
obliteration of the common
cardinal vein and anterior
cardinal veins on the right
side.
• Double superior vena cava:
is due to the persistence of
the left anterior cardinal
vein and failure of the
formation of left
brachiocephalic vein.

20. Azygos vein in adults
Azygos system of veins:
consists of:
series of longitudinal veins
in each side of body that
drain blood from the
body wall and move it
superiorly to drain into
SVC.

21. Azygos vein
• The veins draining the
body wall at first drain into
the posterior cardinal vein.
• Their drainage is soon
transferred to the
longitudinal venous
channels – veins of azygos
line.
• Cranially these channels
drain into the posterior
cardinal veins.

22. • With the retrogression of
the left common cardinal
vein, the left azygos line
loses its communication
with posterior cardinal
vein
• So the blood of this
channel drains into the
right azygos line thr the
post-aortic anastomosis.

23. • The azygous vein is formed
from
- the vein of the right azygos
line.
- the most cranial part of the
right posterior cardinal vein thr
which it opens into the
superior venacava.
• The vertical part of the
hemiazygos and the accessory
hemiazygos vein represent the
left azygos line.
• Their horizontal part are
formed by the post aortic
anatomosis.

24. Summary
• Main veins of the embryo:
visceral vein- vitelline and umbilical vein
somatic vein- cardinal veins
• Formation of portal vein:
a) The lt vitelline vein between entry of superior
mesentric and splenic vein.
b) The dorsal anastomosis.
c) Rt vitelline vein between dorsal anastomosis
and cranial ventral anastomosis.

25. • Left horn of the sinus venosus retrogresses
and then left hepatocardiac channel also
disappear.
• But only the left umbilical vein is left which
carries the blood from the placenta to the
liver.

26. • After birth, left
umbilical vein &
ductus venosus are
obliterated to form
ligamentum teres
hepatis & ligamentum
venosum respectively.

27. • Superior venacava is derived
from
- Rt. common cardinal vein &
the rt. ant. cardinal caudal to
the transverse anastomosis.
• Azygous vein is formed from
- the vein of the right azygos
line.
- the most cranial part of the
right posterior cardinal vein
thr which it opens into the
superior venacava.

28. THANK YOU