Brachiocephalic Veins
The brachiocephalic (innominate) veins are two large venous trunks — right and left — that unite to form the superior vena cava. Both are devoid of valves.
Formation
Each brachiocephalic vein is formed behind the sternoclavicular joint by the union of the corresponding:
- Internal jugular vein
- Subclavian vein
They unite at the lower border of the right 1st costal cartilage to form the superior vena cava.
Comparison: Right vs Left Brachiocephalic Vein
| Feature | Right Brachiocephalic Vein | Left Brachiocephalic Vein |
|---|---|---|
| Length | Short (~2.5 cm) | Long (~6 cm) |
| Course | Vertical — runs vertically downwards from right sternoclavicular joint to lower border of right 1st costal cartilage | Oblique — runs obliquely across the superior mediastinum from left sternoclavicular joint to lower border of right 1st costal cartilage |
| Valves | Absent | Absent |
Tributaries
Right Brachiocephalic Vein
- Right vertebral vein
- Right internal thoracic vein
- Right inferior thyroid vein
- First right posterior intercostal vein
Left Brachiocephalic Vein
- Left vertebral vein
- Left internal thoracic vein
- Left inferior thyroid vein
- First left posterior intercostal vein
- Left superior intercostal vein (unique to the left side)
Important Relations — Left Brachiocephalic Vein
The left brachiocephalic vein crosses the superior mediastinum and lies anterior to the three branches of the arch of aorta (brachiocephalic trunk, left common carotid, left subclavian arteries) — all three arteries are crossed close to their origin by the left brachiocephalic vein.
Clinical Correlation
Central venous access: The subclavian and internal jugular veins — which form the brachiocephalic veins — are the most common sites for central venous catheter insertion. Knowledge of their course and tributaries is essential for safe venous access.
Left superior intercostal vein: This vein drains into the left brachiocephalic vein and is visible as the aortic nipple on a PA chest radiograph when distended (e.g., in SVC obstruction or raised venous pressure).