Blood Supply and Venous Drainage of the Breast
The mammary gland is extremely vascular. Blood reaches it from three arterial sources; venous drainage mirrors the arteries.
Arterial Supply
Three sources supply the breast:
1. Internal Thoracic (Mammary) Artery
- Via its perforating branches, which pierce the 2nd, 3rd, and 4th intercostal spaces
- The main supply to the medial aspect of the breast
- These branches pierce the intercostal muscles and anterior intercostal membrane to reach the breast
2. Axillary Artery
- Via three named branches:
- Lateral thoracic artery (supplies the lateral and inferior aspects)
- Superior thoracic artery
- Acromiothoracic (thoracoacromial) artery — through its pectoral branch
3. Posterior Intercostal Arteries
- Via their lateral branches (lateral cutaneous branches)
- Supply the lateral aspects of the breast
The arteries converge on the breast and are distributed from its anterior surface. The posterior surface is relatively avascular.
Summary Table — Arterial Supply
| Artery | Branch/Route | Region Supplied |
|---|---|---|
| Internal thoracic | Perforating branches (2nd, 3rd, 4th ICS) | Medial breast (main supply) |
| Lateral thoracic | Direct | Lateral and inferior breast |
| Superior thoracic | Direct | Upper breast |
| Acromiothoracic | Pectoral branch | Upper breast |
| Posterior intercostal | Lateral branches | Lateral breast |
Venous Drainage
The veins follow the arteries. Venous blood first converges towards the base of the nipple, forming an anastomotic venous circle, from which it runs in two sets:
Superficial Veins
- Drain into the internal thoracic vein
- Also into the superficial veins of the lower part of the neck
Deep Veins
- Drain into the axillary vein
- Internal thoracic vein
- Posterior intercostal veins
Clinical Significance — Metastasis to the Brain
Route: Cancer cells from breast → posterior intercostal veins → vertebral venous plexus → intracranial dural venous sinuses → brain
The vertebral venous plexus (of Batson) is valveless and allows retrograde flow — important pathway for haematogenous spread of breast cancer to the vertebrae and brain.
Viva Pearls
- Breast is extremely vascular (highly vascular)
- Main arterial supply = internal thoracic artery perforating branches (2nd, 3rd, 4th ICS)
- Axillary contribution via lateral thoracic + superior thoracic + acromiothoracic arteries
- Veins form an anastomotic venous circle at the nipple base before draining in superficial and deep sets
- Superficial veins → internal thoracic vein
- Deep veins → axillary + internal thoracic + posterior intercostal veins
- Posterior surface of breast is relatively avascular
- Brain metastasis route: posterior intercostal → vertebral venous plexus → intracranial sinuses