بسم الله الرحمن الرحيم

Big veins of the mediastinum

The mediastinum

Distribution of veins in the mediastinum

Superior mediastinum

Inferior mediastinum

-Left brachiocephalic vein.

-Right brachiocephalic vein.

-The upper half of superior vena cava.

anterior

middle posterior

-Lower 1/2of S.V.C.

-Terminal part of inferior vena cava.

-Four pulmonary

veins

-Azygos vein.

-Hemiazygos vein.

Brachiocephalic veins

Brachiocephalic veins*Left brachiocephalic vein. *Right brachiocephlic vein.

-Each innominate vein begins behind the corresponding sternoclavicular joint by the union of the internal jugular vein and the subclavian vein.

Beginning

Oblique Vertical Course

Two and half inches++.+ One inch+ . Length

Both veins unite behind the lower border of the 1st costal cartilage to form the (Superior vena cava).

End

*Anteriorly:manubrium.*Posteriorly:branches of the

aortic arch-trachea-left vagus and phrenic nerve.

*inferiorly: arch of aorta.

*On its right side lies the phrenic nerve.*On its left side lies innominate artery.

Relations

Brachiocephalic veins*Left brachiocephalic vein. *Right brachiocephlic vein.

Each innominate vein has the following tributaries from its own side:

1-Vertebral vein .2-Internal thoracic vein.

3-First posterior intercostal vein.4-Inferior thyroid vein.

But… The left innominate vein receives also:1-Left superior intercostal vein.

2-Thymic veins.

tributaries

*Superior vena cava*Beginning:

At the lower border of the first costal cartilage by the union of the two innominate veins.

-Course:It is three inches long (1.5 inches in the superior and 1.5 in the middle mediastinum).

-termination:At the lower border of the right third costal cartilage where it enters the heart

*Superior vena cava*

Tributaries of S.V.C1 -Right and left innominate veins (they form the

S.V.C)2-Azygos arch

(it enters the middle of the S.V.C at the level of the T.4.

So… It is considered as the main tributary

Relations of S.V.C

Medial Lateral Posterior Anterior

-Right vagus.

-Right side of the trachea.

-Right lung and pleura.

-Right phrenic nerve.

-Root of the right lung.

-First two anterior intercostal space.

*Inferior vena cava*-Beginning:

It enters the thorax by piercing the central tendon of the diaphragm the level of T.8.

-Termination:It pierces the pericardium and enters the right atrium at the level of T.6.

-Relations:Anteriorly:Diaphragm.

Posteriorly:Azygos vein and greater splanchnic nerve .

Laterally: phrenic nerve and right lung and pleura

The azygos veins are longitudinal veins on each side of the vertebral column.

They drain venous blood from the posterior thoracic wall and connect the superior vena cava to the .inferior vena cava

Azygos vein

Beginning:It may arise from the back of inferior vena cava at the level of the renal vein at the level of the 2nd lumbar vertebra OR by the union of the right ascending lumbar and subcostal vein.Course:

It enters the thoracic cavity through the aortic opening of the diaphragm on the right side of the aorta with the thoracic duct in between.

Then it ascends anterior to the bodies of the lower 8 thoracic vertebra.

End:It enters the superior vena cava at its middle

*Tributaries of azygos vein*1 -All right posterior

intercostal vein except the 1st vein.

2 -Right subcostal and ascending lumbar veins.

3 -The hemiazygos and accessory hemiazygos veins.

4 -Esophageal vein.5 -pericardial vein.6 -Mediastinal vein.

7 -Right bronchial vein.

Inferior and superior hemiazygos vein**Inferior hemiazygoz

Superior hemiazygos

As the azygos vein begins but it arise from left renal vein.

At the level of T.8 by the union of (4-8)posterior inter costal veins.

Beginning

It enters the thorax by piercing the left crus of the diaphragm and ascends on the left side of the vertebral column.

It descends on the left side of the vertebral column.

Course

It ends by crossing the midline in front of T.9 to end in the azygos vein .

It ends by crossing the midline in front of T.8 to end in the azygos vein .

End

*four pulmonary veins*They carry the oxygenated blood from the

lungs to the left atrium, two from each lung.

*Coronary sinus*It’s a large wide venous channel situated in the

posterior part of coronary sulcus and ends in the right atrium

Tributaries-:1-great cardiac vein2-small cardiac vein

3-middle cardiac vein 4-posterior vein of the left ventricle

5-oblique vein of marshal

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