Oesophagus
Oesophagus
Also known as: esophagus, gullet
The oesophagus is a muscular tube about 25 cm long that carries food from the pharynx to the stomach. It runs through the neck, the posterior mediastinum and the oesophageal hiatus of the diaphragm.
Overview
The oesophagus begins at the lower border of the cricoid cartilage (C6), where it continues from the laryngopharynx. It descends behind the trachea and the left atrium, passes through the oesophageal hiatus in the right crus of the diaphragm at T10, and ends at the cardial orifice of the stomach at about T11, left of the midline. Its parts are cervical, thoracic (the longest) and a short abdominal part.
The tube has three anatomical constrictions, which are where swallowed objects lodge, caustic strictures form and endoscopes meet resistance. The cervical constriction is at the pharyngo-oesophageal junction (cricopharyngeus), about 15 cm from the incisor teeth. The thoracic (broncho-aortic) constriction is where the arch of the aorta crosses (about 22.5 cm) and then the left main bronchus (about 27.5 cm). The diaphragmatic constriction is at the hiatus, about 40 cm from the incisors.
The wall has the usual four layers with three distinctive features. It has no serosa except over the short abdominal part; elsewhere it has a fibrous adventitia. The mucosa is non-keratinised stratified squamous epithelium. The muscularis externa changes from skeletal muscle in the upper third to mixed in the middle third to smooth muscle in the lower third. The upper oesophageal sphincter (cricopharyngeus) is a true anatomical sphincter. The lower oesophageal sphincter is a physiological high-pressure zone.
- Location
Neck and posterior mediastinum, from C6 to T11, in front of the vertebral column. Its lowest part lies just below the diaphragm.
Parts & subdivisions
- Cervical partC6–T1. Behind the trachea, with the recurrent laryngeal nerves in the tracheo-oesophageal grooves.
- Thoracic partSuperior and posterior mediastinum. Indented by the aortic arch and left main bronchus, and lies directly behind the left atrium.
- Abdominal partA short segment, about 1–2.5 cm, below the hiatus. Covered by peritoneum in front and on the left. Joins the stomach at the angle of His.
- Upper oesophageal sphincterFormed by cricopharyngeus, the lowest part of the inferior pharyngeal constrictor. Tonically closed to keep air out of the oesophagus and refluxed material out of the pharynx.
- Physiological sphincter at the gastro-oesophageal junction.
- Z-lineIrregular squamocolumnar junction where pale oesophageal squamous mucosa meets red gastric columnar mucosa. It is displaced upwards in Barrett oesophagus.
Anatomy
- Innervation
Upper striated muscle: branchial motor fibres of the vagus from nucleus ambiguus, via the recurrent laryngeal nerves. Smooth muscle: the oesophageal plexus, with vagal parasympathetic fibres from the dorsal motor nucleus relaying in the myenteric plexus, and sympathetic fibres from the cervical and thoracic trunks and greater splanchnic nerves. Below the plexus the vagi re-form as the anterior (mainly left) and posterior (mainly right) vagal trunks.
- Arterial supply
Cervical: inferior thyroid artery. Thoracic: oesophageal branches of the thoracic aorta and bronchial arteries. Abdominal: oesophageal branches of the left gastric artery and the left inferior phrenic artery.
- Venous drainage
Cervical: inferior thyroid veins. Thoracic: azygos and hemiazygos veins (systemic). Abdominal: left gastric vein (portal). The submucosal venous plexus of the lower oesophagus is therefore a portosystemic anastomosis.
- Lymphatic drainage
Cervical part to the deep cervical nodes; thoracic part to the posterior mediastinal and tracheobronchial nodes; abdominal part to the left gastric and coeliac nodes.
- Relations
Cervical: trachea in front, recurrent laryngeal nerves in the grooves, prevertebral fascia behind, carotid sheaths and thyroid lobes at the sides. Thoracic: trachea, left main bronchus, pericardium and left atrium in front; aorta on the left, later behind; thoracic duct and azygos vein behind and to the right.
- Histology
Non-keratinised stratified squamous epithelium. Submucosal mucous oesophageal glands, with oesophageal cardiac glands near the stomach. Muscularis externa skeletal → mixed → smooth from top to bottom. Adventitia, except the abdominal segment, which has a serosa.
- Development
Develops from the foregut caudal to the respiratory diverticulum. The tracheo-oesophageal septum separates it from the trachea. It lengthens rapidly as the heart and lungs descend.
Function
- Carries the bolus to the stomach by primary and secondary peristalsis.
- Prevents air entering during breathing (UES) and gastric reflux (LES).
- Lubricates the bolus with mucus from submucosal oesophageal glands.
Clinical significance
Oesophageal varices
In portal hypertension, blood is diverted from the left gastric vein into the azygos system through submucosal veins of the lower oesophagus. Rupture causes life-threatening haematemesis. Treatment includes endoscopic band ligation, terlipressin, antibiotics and TIPS.
Oesophageal carcinoma
Squamous cell carcinoma occurs mainly in the upper and middle oesophagus and is linked to smoking, alcohol, very hot drinks, achalasia and nutritional factors. Adenocarcinoma occurs in the lower third, arises from Barrett oesophagus (GERD, obesity) and is now the commoner type in many Western countries. Progressive dysphagia, first to solids and then to liquids, with weight loss, is the classic presentation.
Mallory–Weiss tear vs Boerhaave syndrome
Forceful retching can cause a mucosal tear at the gastro-oesophageal junction, with haematemesis (Mallory–Weiss). It can also cause a transmural rupture, usually of the left posterolateral distal oesophagus, with mediastinitis, surgical emphysema and shock (Boerhaave), which is a surgical emergency.
Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.