The oesophagus is a muscular tube, roughly twenty-five centimeters long, connecting the pharynx to the stomach. It begins at the level of the sixth cervical vertebra, passing downwards through the superior and posterior mediastinum. It pierces the diaphragm at the esophageal hiatus, usually at the tenth thoracic vertebra, before terminating at the cardia of the stomach.
In the neck, the trachea lies anterior to the oesophagus, while the vertebral column sits posteriorly. Within the thorax, the aortic arch and left main bronchus cross anteriorly, creating normal anatomical narrowings. The thoracic duct runs posterior to it, and the vagus nerves form a plexus around its muscular walls as it approaches the abdominal cavity.
The wall of the oesophagus consists of four distinct tissue layers from the lumen outward: the mucosa, submucosa, muscularis propria, and adventitia.
Blood supply to the oesophagus is segmental, reflecting its long vertical course through multiple body cavities. The cervical portion receives blood from the inferior thyroid arteries. The thoracic portion is supplied directly by branches from the descending thoracic aorta and bronchial arteries. The abdominal portion receives blood from the left gastric artery and inferior pharyngeal branches.
Venous drainage follows a critical pattern for clinical nursing. The upper and middle oesophageal veins drain into the systemic circulation via the azygous and hemiazygous systems. The lower oesophageal veins drain into the portal venous system via the left gastric vein. This junction forms a vital portosystemic anastomotic site where portal hypertension causes engorgement, known as oesophageal varices.
Lymphatic drainage flows to the deep cervical nodes from the upper third, posterior mediastinal nodes from the middle third, and gastric and celiac nodes from the lower third.
Motor and sensory innervation of the oesophagus coordinates the complex process of moving food downward while preventing reflux.
Swallowing, or deglutition, occurs in three distinct phases: the voluntary oral phase, the involuntary pharyngeal phase, and the involuntary oesophageal phase.
Once the food bolus enters the oesophagus, primary peristalsis begins. This is a coordinated wave of circular muscle contraction behind the bolus, coupled with relaxation ahead of it, sweeping downwards toward the stomach at about two to four centimeters per second. If a bolus becomes stuck or moves slowly, local distension triggers secondary peristalsis mediated entirely by the enteric nervous system to clear the lumen completely. Gravity assists this transport, but strong muscular contractions allow people to swallow even when lying flat.
Two high-pressure zones act as gatekeepers at either end of the oesophagus, preventing air entry during breathing and gastric acid reflux during digestion.
| Sphincter | Anatomical Location | Primary Function |
|---|---|---|
| Upper Oesophagal Sphincter (UOS) | Junction of pharynx and oesophagus (cricopharyngeus muscle) | Prevents air from entering the gastrointestinal tract during inspiration |
| Lower Oesophagal Sphincter (LOS) | Junction of oesophagus and stomach (T10-T11 level) | Prevents acidic gastric contents from refluxing into the lower oesophagus |
The LOS maintains constant tonic contraction. It relaxes briefly during swallowing to allow food passage, aided by the pinch-cock action of the right crus of the diaphragm.
Pathological conditions of the oesophagus often manifest as dysphagia (difficulty swallowing), odynophagia (painful swallowing), or heartburn.