Longest part of oesophagus; passes through superior + posterior mediastinum.

Extent

• Total oesophagus ~25 cm, C6 to stomach

Course

Superior mediastinum (T1–T4): between trachea (ant) + vertebral column (post); slightly left of median plane; related to left recurrent laryngeal nerve in tracheo-oesophageal groove

At T4/T5: enters posterior mediastinum; passes behind left principal bronchus; crossed by arch of aorta

Posterior mediastinum (T5–T10): posterior to left atrium (separated by pericardium + oblique sinus); descends anterior to vertebral column; inclines left near diaphragm; through oesophageal hiatus (right crus) at T10

Oesophageal Hiatus

Right crus contributes to physiological lower oesophageal sphincter

Relations

Anterior:

LA enlargement → smooth impression on barium swallow

Posterior (above-down): vertebral column, longus colli (upper thorax), thoracic duct, azygos vein, right posterior intercostal arteries, descending thoracic aorta (lower)

Right: right pleura/lung, azygos vein + arch, right vagus nerve

Left: left pleura/lung, left subclavian artery (superior mediastinum), arch of aorta, descending thoracic aorta, thoracic duct, left recurrent laryngeal nerve (tracheo-oesophageal groove)

Constrictions (4)

Cricopharyngeal = narrowest; foreign bodies/corrosive strictures/carcinoma common at constrictions; endoscopic landmarks

Blood Supply

Segmental supply → vulnerable during surgery if multiple vessels interrupted

Venous Drainage

Lower oesophagus = major portosystemic anastomosis site (left gastric vein ↔ oesophageal veins ↔ azygos system); portal HTN → oesophageal varices → haematemesis

Lymphatic Drainage

Longitudinal submucosal spread → distant node involvement → poor prognosis

Nerve Supply

• Oesophageal plexus: right vagus + left vagus + sympathetic (thoracic trunks/splanchnic nerves)
• Vagal trunks regroup distally: anterior vagal trunk mainly from left vagus; posterior vagal trunk mainly from right vagus (each contains mixed fibres)

Oesophageal pain can mimic cardiac pain (shared upper thoracic spinal segments)

Applied Anatomy

Carcinoma of Oesophagus

• More common: males, older adults
• SCC: upper/middle; adenocarcinoma: lower (often Barrett’s); middle third classic teaching site
• Features: progressive dysphagia (solids→liquids), weight loss, regurgitation, odynophagia, hoarseness (RLN), TOF (cough on swallowing)
• Spread: local (trachea, bronchi, aorta, pericardium, RLN); lymphatic (longitudinal, mediastinal+coeliac); blood (liver, lungs, bone)
• Poor prognosis: late presentation, longitudinal lymphatic spread, no serosa, early mediastinal invasion

Dysphagia causes — carcinoma, stricture, achalasia, LA enlargement, mediastinal nodes, aortic aneurysm, dysphagia lusoria (aberrant right subclavian)

Achalasia

• LES relaxation failure (myenteric plexus degeneration)
• Dysphagia both solids+liquids from start, regurgitation of undigested food
• Bird-beak/rat-tail on barium swallow; dilated oesophagus above narrowing

Oesophageal Varices

• Portal HTN (cirrhosis) → ↑left gastric vein pressure → submucosal venous dilation → rupture → massive haematemesis

GORD — LES failure → reflux → oesophagitis, peptic stricture, Barrett’s, adenocarcinoma risk

Oesophageal Perforation (Boerhaave syndrome)

• Spontaneous rupture after severe vomiting; common site: left posterolateral wall, lower thoracic oesophagus
• Complications: mediastinitis, pleural contamination, sepsis

Barium Swallow Impressions

The thoracic oesophagus is the longest part of the oesophagus. It passes through the superior and posterior mediastinum and is clinically important because of its constrictions, close mediastinal relations, portosystemic venous anastomosis, longitudinal lymphatics, and carcinoma spread.

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Extent

The oesophagus is about 25 cm long and extends from C6 to the stomach.

The thoracic part extends from:

It passes through:

1. Superior mediastinum
2. Posterior mediastinum

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Course

Superior Mediastinum

From T1 to T4:

• Lies between trachea anteriorly and vertebral column posteriorly.
• Slightly left of median plane.
• Related to the left recurrent laryngeal nerve in the tracheo-oesophageal groove.

At T4/T5

At the level of tracheal bifurcation:

• Oesophagus enters posterior mediastinum.
• It passes behind the left principal bronchus.
• It is crossed by the arch of aorta and related to the left bronchus.

Posterior Mediastinum

From T5 to T10:

• Lies posterior to left atrium, separated by pericardium and oblique sinus.
• Descends in front of vertebral column.
• Inclines to the left as it approaches the diaphragm.
• Passes through the oesophageal hiatus in the right crus at T10.

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Oesophageal Hiatus

The right crus contributes to the physiological lower oesophageal sphincter.

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Relations

Anterior Relations

Clinical point:

• Left atrial enlargement produces a smooth impression on barium swallow.

Posterior Relations

From above downwards, posterior relations include:

• Vertebral column
• Longus colli in upper thorax
• Thoracic duct
• Azygos vein
• Right posterior intercostal arteries
• Descending thoracic aorta in lower posterior mediastinum

Right Relations

• Right pleura and lung
• Azygos vein and arch of azygos
• Right vagus nerve

Left Relations

• Left pleura and lung
• Left subclavian artery in superior mediastinum
• Arch of aorta
• Descending thoracic aorta
• Thoracic duct
• Left recurrent laryngeal nerve in tracheo-oesophageal groove

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Constrictions

The oesophagus has four important constrictions.

The cricopharyngeal constriction is the narrowest point.

Clinical importance:

• Foreign bodies lodge here.
• Corrosive strictures form here.
• Carcinoma is common near constrictions.
• Endoscopists use the incisor distances as landmarks.

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Blood Supply

Arterial supply is segmental.

Segmental arterial supply makes the oesophagus vulnerable during surgery if multiple segmental vessels are interrupted.

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Venous Drainage

The lower oesophagus is a major site of portosystemic anastomosis:

Left gastric vein, portal system
↔ Oesophageal veins
↔ Azygos system, systemic venous system

Clinical importance:

• Portal hypertension causes oesophageal varices.
• Rupture causes massive haematemesis.

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Lymphatic Drainage

Oesophageal lymphatics are mainly longitudinal in the submucosa.

Clinical importance:

• Cancer spreads longitudinally for long distances before obvious local symptoms.
• Nodes above and below the tumour may be involved.
• This contributes to poor prognosis.

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Nerve Supply

The thoracic oesophagus is supplied by the oesophageal plexus.

Oesophageal Plexus

Formed by:

• Right vagus nerve
• Left vagus nerve
• Sympathetic fibres from thoracic sympathetic trunks and splanchnic nerves

It surrounds the oesophagus in the posterior mediastinum.

Vagal Trunks

As the plexus descends, fibres regroup:

Each trunk contains fibres from both vagi because the fibres mix in the oesophageal plexus.

Functional Supply

Oesophageal pain can mimic cardiac pain because visceral afferents enter upper thoracic spinal segments.

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Applied Anatomy

Carcinoma of Oesophagus

Important facts:

• More common in males and older adults.
• Squamous cell carcinoma often affects upper/middle oesophagus.
• Adenocarcinoma often affects lower oesophagus and may arise in Barrett’s oesophagus.
• Middle third is a common site in classic anatomy teaching.

Features:

• Progressive dysphagia, first solids then liquids
• Weight loss
• Regurgitation
• Odynophagia
• Hoarseness due to recurrent laryngeal nerve involvement
• Tracheo-oesophageal fistula causing cough after swallowing

Spread:

Poor prognosis is due to:

• Late presentation
• Longitudinal lymphatic spread
• Lack of serosal covering
• Early invasion of mediastinal structures

Dysphagia

Causes related to thoracic oesophagus:

• Carcinoma
• Stricture
• Achalasia
• Extrinsic compression by left atrial enlargement
• Mediastinal lymph nodes
• Aortic aneurysm
• Aberrant right subclavian artery, producing dysphagia lusoria

Achalasia

Achalasia is failure of relaxation of the lower oesophageal sphincter due to degeneration of the myenteric plexus.

Features:

• Dysphagia for both solids and liquids from the beginning
• Regurgitation of undigested food
• Bird-beak or rat-tail appearance on barium swallow
• Dilated oesophagus above the narrowing

Oesophageal Varices

Cause:

• Portal hypertension, commonly due to cirrhosis

Mechanism:

Portal pressure rises
→ Left gastric vein pressure rises
→ Lower oesophageal submucosal veins dilate
→ Varices form
→ Rupture causes massive haematemesis

Gastro-Oesophageal Reflux Disease

Failure of the lower oesophageal sphincter causes acid reflux.

Complications:

• Oesophagitis
• Peptic stricture
• Barrett’s oesophagus
• Adenocarcinoma risk

Oesophageal Perforation

Spontaneous rupture after severe vomiting is called Boerhaave syndrome.

Common site:

• Left posterolateral wall of lower thoracic oesophagus

Complications:

• Mediastinitis
• Pleural contamination
• Sepsis

Barium Swallow Impressions

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