Blood Supply, Venous Drainage and Lymphatics of the Thoracic Oesophagus
Arterial Supply
The arterial supply of the thoracic oesophagus is segmental — different levels are supplied by different arteries:
| Segment | Artery | Origin |
|---|---|---|
| Upper thoracic oesophagus | Oesophageal branches of the bronchial arteries | Right bronchial artery (from 3rd right posterior intercostal); Left bronchial arteries (from descending thoracic aorta) |
| Middle thoracic oesophagus | Oesophageal branches directly from the descending thoracic aorta (usually 2–3 branches) | Descending thoracic aorta |
| Lower thoracic oesophagus | Oesophageal branches of the left gastric artery (these ascend through the oesophageal hiatus) | Left gastric artery (branch of coeliac trunk) |
Important: The arterial supply is segmental without significant longitudinal anastomoses — this makes the oesophagus vulnerable to ischaemia if its segmental supply is interrupted during surgery.
Venous Drainage
Venous drainage is more extensive than arterial supply and forms an important portosystemic anastomosis:
| Segment | Vein | Drains Into |
|---|---|---|
| Upper thoracic | Oesophageal veins | Azygos vein (right side) |
| Middle thoracic | Oesophageal veins | Azygos vein and hemiazygos vein |
| Lower thoracic | Oesophageal veins | Left gastric vein (portal system) |
Portosystemic anastomosis: The lower oesophageal veins connect the portal system (via left gastric vein → portal vein) with the systemic system (via azygos/hemiazygos → superior vena cava). This is one of the four major portosystemic anastomoses in the body.
Clinical significance: In portal hypertension (e.g., liver cirrhosis), the portal pressure forces blood retrograde through the left gastric vein into the lower oesophageal veins → oesophageal varices (submucosal venous dilatations). These can rupture causing massive upper gastrointestinal haemorrhage.
Lymphatic Drainage
Lymphatic drainage of the oesophagus is longitudinal — cancer cells spread along the length of the oesophagus in the submucosal lymphatic plexus before reaching regional nodes. This explains why oesophageal carcinoma tends to spread extensively before becoming clinically apparent.
| Segment | Regional Lymph Nodes |
|---|---|
| Upper thoracic oesophagus | Posterior mediastinal lymph nodes → tracheobronchial nodes |
| Middle thoracic oesophagus | Posterior mediastinal lymph nodes → nodes along the aorta |
| Lower thoracic oesophagus | Posterior mediastinal nodes → nodes along the left gastric artery → coeliac nodes |
Ultimate drainage: All thoracic oesophageal lymphatics drain into the thoracic duct (left-sided drainage) or the right lymphatic duct (right-sided upper thoracic drainage).
Key point: The submucosal lymphatic plexus of the oesophagus allows early lymphatic spread both cranially and caudally, which accounts for the poor prognosis of oesophageal carcinoma — nodes above and below the primary tumour may both be involved.