Söögitoru

Söögitoru, in English the esophagus, is a muscular tube of the upper digestive tract that transports swallowed material from the pharynx to the stomach. In adults it is about 25 centimeters long and runs behind the trachea through the mediastinum, passing the diaphragm at the esophageal hiatus to join the stomach at the gastroesophageal junction.

Anatomy and histology: The esophageal lining is non-keratinized stratified squamous epithelium. The submucosa contains mucus-secreting esophageal glands that help lubricate the lumen. The muscularis externa has an inner circular and an outer longitudinal layer; the upper third is primarily skeletal muscle, the lower third is smooth muscle, and the middle portion contains a mixture of both. The thoracic portion is encased by adventitia, while the abdominal portion lies near the stomach and forms part of the gastroesophageal junction. The lower esophageal sphincter (LES) functions as a physiological barrier to reflux, aided by the diaphragmatic crura and the angle of His. Blood supply comes from branches of the inferior thyroid, thoracic aorta, and left gastric arteries; venous drainage mirrors these routes. Lymphatic drainage targets deep cervical, posterior mediastinal, and left gastric/celiac nodes.

Physiology: Primary peristalsis moves swallowed material downward, coordinated by the enteric nervous system. If needed, secondary peristalsis can be elicited by luminal distension. Motility and tone are influenced by neural and hormonal signals, while the LES maintains a barrier against retrograde flow. The esophagus also secretes mucus to aid transit.

Clinical relevance: Disorders include gastroesophageal reflux disease (GERD), esophagitis, Barrett’s esophagus, hiatal hernia, strictures, and esophageal cancer (varying by region). Achalasia involves impaired LES relaxation and absent peristalsis. Diagnosis typically uses endoscopy, manometry, and imaging; treatment ranges from lifestyle modification and acid suppression to endoscopic or surgical interventions for complex cases.