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OESOPHAGUS

1. Introduction • The oesophagus is a 25 cm long muscular tube that connects the pharynx to the stomach. • Function: Transport of food and liquid by coordinated peristalsis. • It lies in the neck, thorax, and upper abdomen. • Unlike most of the gastrointestinal tract, it has no serosal layer. 2. Gross Anatomy • Length: ~25 cm in adults (18 cm in children). • Extent: • Begins at the lower border of cricoid cartilage (C6 vertebra). • Ends at the cardiac orifice of stomach (T11 vertebra). Parts 1. Cervical oesophagus (C6–T1) 2. Thoracic oesophagus (T1–T10) 3. Abdominal oesophagus (T10–T11) 3. Constrictions of the Oesophagus (Clinically important for endoscopy and foreign body lodgment) 1. Cricopharyngeal constriction – C6, upper esophageal sphincter. 2. Aortic arch constriction – T4. 3. Left main bronchus constriction – T5. 4. Diaphragmatic constriction – T10, lower esophageal sphincter. 4. Relations Cervical Oesophagus • Anterior: Trachea. • Posterior: Vertebral column. • Lateral: Carotid sheath, thyroid gland. Thoracic Oesophagus • Anterior: Trachea, left atrium. • Posterior: Vertebral bodies, thoracic duct. • Lateral: Aorta (left), azygos vein (right). Abdominal Oesophagus • Related to left lobe of liver and diaphragm. 5. Histology Layers of oesophageal wall (from inside → out): 1. Mucosa – Stratified squamous epithelium (non-keratinized). 2. Submucosa – Esophageal glands (mucus-secreting). 3. Muscularis externa: • Upper 1/3 → Skeletal muscle. • Middle 1/3 → Mixed (skeletal + smooth). • Lower 1/3 → Smooth muscle. 4. Adventitia – Fibrous covering (no serosa). 6. Blood Supply • Cervical: Inferior thyroid artery. • Thoracic: Branches from bronchial arteries, aorta. • Abdominal: Left gastric artery. Venous drainage: • Azygos vein → SVC. • Left gastric vein → Portal vein. 👉 This forms the porto-systemic anastomosis → site of esophageal varices. 7. Nerve Supply • Parasympathetic: Vagus nerve (peristalsis, secretion). • Sympathetic: Thoracic sympathetic chain (vasoconstriction, sphincter tone). • Enteric nervous system: Myenteric and submucosal plexuses. 8. Physiology • Peristalsis: Coordinated contractions push bolus down. • Sphincters: • Upper esophageal sphincter (UES): Prevents air entry, regurgitation. • Lower esophageal sphincter (LES): Prevents gastroesophageal reflux. 9. Applied Anatomy • Achalasia cardia – Failure of LES relaxation → dysphagia. • Esophageal varices – Portal hypertension complication. • GERD (Gastroesophageal reflux disease). • Esophageal carcinoma – Squamous cell (upper/mid), adenocarcinoma (lower). • Boerhaave’s syndrome – Spontaneous rupture of oesophagus. 10. Key Clinical Points • Sites of foreign body impaction = 4 constrictions. • Esophagus lacks serosa, so cancers spread early. • Strong lymphatic network → rapid metastasis.