DEVELOPMENT OF THE VEINS

three embryonic

venous systems comprising:

1. The vitelline system, draining the

yolk sac and gut tube

2. The umbilical system, bringing

oxygen-rich blood from the

placenta

3. The cardinal system, draining the

body wall, neck, and head

1. The remodeling makes

the right-side dominant

for the vitelline and

cardinal systems,

2. The umbilical vein on the

right-side degenerates

3. Remodeling results in

the formation of the

superior and inferior

venae cavae (SVC & IVC)

4.Makes the left side dominant for

the umbilical system, although it

still drains into the right side of the

heart

5. A shunt (vessel) develops in the liver

as the ductus venosus which allows

blood in the left umbilical vein to

drain into the inferior vena cava

6. Remodeling of venous system is more

complex than in the arterial system

RVV and LVV come from yolk sac

Little capillaries(sinusoids) form after V V passes through the GI tract and enters the liver

NB: S—Trasnversum becomes the diaphragm

Sinusoids drain into hepatic vein( L and R hepatic from iVC)

Splenic + SMV +IMV= hepatic portal vein

SMV and IMV are capillary networks formed in GI tract

Vitelline produces 4 main; i. liver sinusoids,

ii. ductus venosus

iii. the portal venous system and

iv. the cranial (post-hepatic) part

of the Inferior Vena Cava(IVC)

Umbilical vein derivatives

• The right umbilical vein

degenerates

• The left umbilical vein loses

its connection to the left

sinus horn

• It drains into the IVC via the

ductus venosus

NB: reminant of L umbilical vein is Ligamentum Teres

Dev of viteline and umbilical occurs second to 3rd week

THE CARDINAL VEIN SYSTEM

Starts around 5th week

The cardinal system initially consists

of symmetric, paired anterior and

posterior cardinal veins

• They drain into the sinus horns via

short common cardinal veins

• The anterior cardinals drain the head

and neck

• The posterior cardinals drain the body

wall

Posterior cardinal veins degenerate and become subcardinal(medial dorsal body wall especially kidney and gonads) and supracardinal(drains thoracic wall) veins

RIGHT SUBCARDINAL VEIN

The right subcardinal

vein forms the next most

caudal part of the IVC

after the right vitelline

vein

• The left cardinal vein will

then drain into this part of

the inferior vena cava

DERIVATIVE OF THE RT. ABDOMINAL SUPRACARDINAL

VEIN

It forms the inferior vena

cava (IVC) between renal

tributary and bifurcation of

iliac veins

FORMATION OF THE IVC

The inferior vena cava

(IVC), from cranial to

caudal, is derived from:

i. The right vitelline vein

ii. The right subcardinal vein

iii. The right supracardinal

vein

iv. The posterior cardinal

ANTERIOR (OR PRE-) CARDINAL VEIN 1

The anterior cardinal

system

drains the head, neck

and upper limbs

• The distal Ant. Cardinal

vein forms internal

jugular veins (on either

side)

ANTERIOR CARDINAL VEIN (2)

The Right common cardinal vein

[yellow circle] with contribution

from the proximal right

anterior cardinal becomes

Superior vena cava (SVC) [Red

circle]

ii. The proximal Left anterior

cardinal vein degenerates, so the

left brachiocephalic

(innominate) vein forms to

drain the left internal jugular

vein into the SVC

NB; supracardinal vein become azygous, hemiazygous and accessory hemiazygous vein and the subcardianl major iVC