Internal Thoracic Artery and Azygos Vein

Question 1

What is the origin of the internal thoracic artery?

Answer 1

First part of the subclavian artery opposite the thyrocervical trunk

Question 2

Describe the course of the internal thoracic artery

Answer 2

1. Descends medially behind sternal end of clavicle and 1st costal cartilage
2. Vertically downwards 2 cm from lateral border of sternum till 6th intercostal space
3. Terminates in the sixth intercostal space by dividing into the superior epigastric and musculophrenic arteries

Question 3

What are the relations of the internal thoracic artery?

Answer 3

Clarting jugs costs phrens and will brachio heart
Above the first costal cartilage behind:
1. The sternal end of the clavicle
2. The internal jugular vein
3. The first costal cartilage
4. The phrenic nerve
5. The brachiocephalic vein

Question 4

What are the branches of the internal thoracic artery?

Answer 4

MAPP

1. The pericardiacophrenic artery arises in the root of the neck and accompanies the phrenic nerve to reach the diaphragm. It supplies the pericardium and the pleura
2. The mediastinal arteries are small irregular branches that supply the thymus, in front of the pericardium, and the fat in the mediastinum.
3. Two anterior intercostal arteries are given to each of the upper six intercostal spaces.
4. The perforating branches accompany the anterior cutaneous nerves. In the female, the perforating branches in the second, third and fourth spaces are large and supply the breast.
5. The superior epigastric artery runs downwards behind the seventh costal cartilage and enters the rectus sheath by passing between the sternal and costal slips of the diaphragm.
6. The musculophrenic artery runs downwards and laterally behind the seventh, eighth, and ninth costal cartilages. It gives two anterior intercostal branches to each of these three spaces.

Question 5

What is the azygos vein?

Answer 5

Drains the thoracic wall and the upper lumbar region
Occupies the posterior mediastinum and upper part of the posterior abdominal wall
Connects the superior and inferior venae cavae
Connects portal venous system, caval venous system and vertebral venous system (PVC)

Question 6

Which three veins form the azygos vein?

Answer 6

Lumbar azygos, right ascending lumbar and right subcostal veins

Question 7

Describe the course of the azygos vein?

Answer 7

Passes through the aortic opening of diaphragm
Ascends to the fourth thoracic vertebra and arches over the root of the right lung
Joins the posterior aspect of the superior vena cava

Question 8

What are the tributaries of the azygos vein?

Answer 8

1. Right superior intercostal vein formed by union of the second, third and fourth posterior intercostal veins.
2. Fifth to eleventh right posterior intercostal veins.
3. Hemiazygos vein at the level of lower border of eighth thoracic vertebra.
4. Accessory hemiazygos vein at the level of upper border of eighth thoracic vertebra.
5. Right bronchial vein, near the terminal end of the azygos vein.
6. Several oesophageal, mediastinal, pericardial veins (mop)