Intercostal VAN

Question 1

Neurovascular bundle (VAN)

Answer 1

Protected by costal groove of rib

Found between internal and innermost intercostal layers of muscle

Question 2

Intercostal nerves

Answer 2

Enter space between the parietal pleura and internal intercostal membrane
Arises from the anterior rami of T1-T11:
1) 1-6 intercostal nerves pass along intercostal space
2) 7-10 intercostal nerves pass deep to costal cartilages of ribs to supply anterior abdominal wall
3) 11-12 intercostal nerves pass straight to supply anterior abdominal wall

Question 3

Intercostal Arteries

Answer 3

Posterior intercostal arteries (11)

• 1-2 posterior intercostal arteries arise from the superior intercostal artery (branch of subclavian artery)
• 3-12 posterior intercostal arteries arises from the descending thoracic aorta

Anterior intercostal arteries (9)

• 1-6 anterior intercostal arteries arise from the internal thoracic artery
• 6-12 anterior intercostal arteries arise from the musculophrenic artery (terminal branch of internal thoracic)

*Right posterior intercostal arteries are longer than the left because the aorta lies on the left side

Question 4

Intercostal veins

Answer 4

Anterior intercostal veins
- Drain into the internal thoracic vein and musculophrenic vein (which then empty into the subclavian vein and then into SVC)

Posterior intercostal veins

Right side:

• Lower 8 intercostal veins drain into the azygous vein (formed by the union of right lumbar ascending vein and subcostal vein)
• Azygous vein receives tributaries from the hemiazygous vein and right superior intercostal vein

Left side:

• 2-3 intercostal veins drain into the left superior intercostal vein (which drains into left brachiocephalic vein)
• 4-8 intercostal veins drain into the superior hemiazygous vein (drains into the inferior hemiazygous vein)
• Lowest 4-5 intercostal veins drain into the inferior hemiazygous vein (formed from left lumbar ascending vein and left subcostal vein)