Learning objective
By the end of this lesson, learners should be able to describe the anatomy, blood supply, innervation, and clinical relevance of the oesophagus, including sphincters, anatomical constrictions, and common pathological conditions.
Overview of the oesophagus
The oesophagus is a fibromuscular tube, approximately 25 cm long, that transports food from the pharynx to the stomach.
- Origin: Inferior border of the cricoid cartilage (C6)
- Termination: Cardiac orifice of the stomach (T11)
It shares structural features with the alimentary tract and is supported by adventitia, muscle layers, submucosa, and mucosa. Food is propelled via peristalsis, a coordinated rhythmic contraction of its muscles.
Anatomical course
- Cervical part: Begins at C6, continuous with the laryngopharynx.
- Thoracic part: Descends through the superior mediastinum, between the trachea and vertebral bodies T1–T4.
- Abdominal part: Passes through the oesophageal hiatus of the diaphragm at T10 and joins the stomach at T11.
Anatomical structure
The oesophagus consists of four layers:
- Adventitia: Outer connective tissue layer. Note: distal intraperitoneal portion is covered by serosa.
- Muscle layer:
- Superior third: Striated (voluntary) muscle
- Middle third: Striated + smooth muscle
- Inferior third: Smooth muscle
- Submucosa
- Mucosa: Non-keratinised stratified squamous epithelium; continuous with gastric columnar epithelium
Function: Muscular layers generate peristaltic waves to move food. Dysregulation leads to dysphagia.
Oesophageal sphincters
Upper oesophageal sphincter (UES)
- Formed by the cricopharyngeus muscle
- Anatomical sphincter of striated muscle
- Normally constricted to prevent air entry into the oesophagus
Lower oesophageal sphincter (LES)
- Located at the gastro-oesophageal junction (T11)
- Physiological sphincter maintained by:
- Acute angle of oesophagus entering stomach
- Intra-abdominal compression
- Prominent mucosal folds
- Pinch-cock effect of right crus of diaphragm
- Function: Prevents reflux of gastric contents; relaxes during peristalsis
Anatomical relations and constrictions
Four physiological constrictions where food or foreign bodies may lodge (ABCD):
- A: Arch of aorta
- B: Bronchus (left main stem)
- C: Cricoid cartilage
- D: Diaphragmatic hiatus
Relations:
| Region | Anterior | Posterior | Right | Left |
|---|---|---|---|---|
| Cervical/Thoracic | Trachea | Thoracic vertebral bodies | Thoracic duct, azygous veins | Left recurrent laryngeal nerve, aortic arch |
| Abdominal | Posterior heart | Left crus of the diaphragm | Right vagus | Left vagus |
Vasculature
Thoracic oesophagus:
- Arteries: Branches of the thoracic aorta, the inferior thyroid artery
- Veins: Azygous system, inferior thyroid vein
Abdominal oesophagus:
- Arteries: Left gastric artery, left inferior phrenic artery
- Veins:
- Portal via the left gastric vein
- Systemic via the azygous vein → forms a porto-systemic anastomosis
Innervation
- Oesophageal plexus: Parasympathetic vagal trunks + sympathetic fibers (cervical & thoracic)
- Upper third (striated): Nucleus ambiguus
- Lower third (smooth): Dorsal motor nucleus of vagus
Lymphatic drainage
- Superior third: Deep cervical lymph nodes
- Middle third: Superior & posterior mediastinal nodes
- Inferior third: Left gastric and celiac nodes
Clinical relevance
Barrett’s oesophagus
- Metaplasia of lower oesophageal squamous epithelium → gastric columnar epithelium
- Usually due to chronic acid reflux from LES dysfunction
- Symptom: Long-term heartburn
- Monitored via endoscopy for potential malignancy
Oesophageal carcinoma
- 2% of UK malignancies
- Symptoms: Progressive dysphagia, weight loss
- Types:
- Squamous cell carcinoma: Any level
- Adenocarcinoma: Inferior third, associated with Barrett’s oesophagus
Oesophageal varices
- Dilated submucosal veins in portal-systemic anastomosis
- Usually from portal hypertension (e.g., cirrhosis)
- Risk: Haematemesis
- High prevalence in alcoholics
