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    Related Topics

    From Digestive System

    Common Hepatic Duct
    Carries bile from liver to bile duct.
    Anus
    Opening through which feces are expelled.
    Major Duodenal Papilla
    Opening for bile and pancreatic ducts into duodenum.
    Epiploic Appendages
    Fat-filled pouches attached to colon.
    Ileum
    Final and longest portion of the small intestine.
    Palatine Tonsils
    Lymphatic tissues on either side of the oropharynx.
    Fundus
    Upper curved portion of the stomach.
    Nasopharynx
    Superior region of pharynx behind the nasal cavity.
    Descending Colon
    Vertical segment of the colon on the left side.
    Oropharynx
    Middle region of the pharynx behind the oral cavity.
    Liver
    Largest gland in the body with roles in metabolism and bile production.
    Tongue
    Muscular organ aiding in taste, speech, and food manipulation.
    Laryngopharynx
    Lower part of pharynx leading to esophagus.
    Right Lobe
    Larger functional lobe of the liver.
    Cecum
    First part of large intestine.
    Tail of Pancreas
    Tapered end of pancreas near spleen.
    Rugae of Stomach
    Internal folds allowing expansion of the stomach.
    Cheeks
    Lateral walls of the oral cavity composed of muscle and fat.
    Jejunum
    Second portion of the small intestine.
    Hard Palate
    Bony anterior portion of the roof of the mouth.
    Cardia
    Upper opening of the stomach.
    Vermiform Appendix
    Worm-like appendage of the cecum.
    Sigmoid Colon
    S-shaped final segment of the colon.
    Peritoneum
    Serous membrane lining the abdominal cavity.
    Lingual Frenulum
    Fold of mucous membrane anchoring the tongue to the floor of the mouth.

    Esophagus

    Reviewed by our medical team

    Muscular tube conveying food from the pharynx to the stomach.

    Overview

    The esophagus is a muscular tube that transports food and liquids from the pharynx to the stomach. It is part of the upper gastrointestinal tract and plays a central role in the swallowing process. Despite having no digestive or absorptive function, the esophagus is essential for initiating the movement of ingested material into the digestive system. Its proper function depends on coordinated muscle contractions and the integrity of specialized sphincters.

    Location

    The esophagus is located in the posterior mediastinum of the thorax and extends from the pharynx (C6 vertebra) to the stomach (T11 vertebra). It has three parts:

    • Cervical esophagus: Located in the neck, posterior to the trachea and anterior to the vertebral column

    • Thoracic esophagus: Descends through the thorax in the posterior mediastinum

    • Abdominal esophagus: A short segment that passes through the diaphragm at the esophageal hiatus (T10) before entering the stomach

    The esophagus lies in close proximity to key structures such as the trachea, aorta, vagus nerves, and left atrium.

    Structure

    The esophagus is approximately 25 cm long and consists of four histological layers:

    • Mucosa: Lined by non-keratinized stratified squamous epithelium, designed to resist abrasion

    • Submucosa: Contains connective tissue, blood vessels, lymphatics, and mucus-secreting glands

    • Muscularis externa: Composed of two layers—inner circular and outer longitudinal. The upper third contains skeletal muscle, the middle third a mix, and the lower third smooth muscle

    • Adventitia: The outermost layer composed of connective tissue that anchors the esophagus to surrounding structures

    There are two physiologic sphincters:

    • Upper esophageal sphincter (UES): Formed by the cricopharyngeus muscle; prevents air from entering the esophagus

    • Lower esophageal sphincter (LES): A functional zone at the gastroesophageal junction that prevents reflux of gastric contents

    Function

    The primary function of the esophagus is:

    • Conduction of food and liquids: Transports ingested material from the oropharynx to the stomach using peristaltic contractions

    Secondary functions include:

    • Protecting airway during swallowing: Coordinated closure of the UES prevents aspiration

    • Preventing reflux: The LES maintains a barrier to stop gastric acid and contents from entering the esophagus

    Physiological Role(s)

    The esophagus plays several key roles in digestive physiology:

    • Swallowing (deglutition): A complex reflex involving over 30 muscles and controlled by brainstem centers

    • Peristalsis: Sequential, wave-like muscle contractions that push food downward

    • Lower esophageal tone regulation: LES relaxes during swallowing and contracts at rest to prevent reflux

    • Mucosal protection: Mucus secreted by glands helps lubricate the passage and protect against acidic or mechanical injury

    Clinical Significance

    The esophagus is involved in a number of common and serious medical conditions:

    • Gastroesophageal reflux disease (GERD): Weak LES tone leads to acid reflux, heartburn, and potential esophagitis

    • Esophageal cancer: Includes squamous cell carcinoma (upper and middle esophagus) and adenocarcinoma (often in the distal esophagus or at the gastroesophageal junction)

    • Esophageal varices: Dilated veins in the esophagus due to portal hypertension; risk of life-threatening bleeding

    • Achalasia: A motility disorder where LES fails to relax and peristalsis is absent; results in dysphagia and regurgitation

    • Hiatal hernia: Part of the stomach herniates through the diaphragm, often weakening LES function and contributing to GERD

    • Esophagitis: Inflammation from reflux, infection (e.g., Candida), or radiation

    • Foreign bodies or strictures: Can cause obstruction, especially in children or those with chronic reflux-induced narrowing

    Evaluation of esophageal disorders may include barium swallow studies, endoscopy, manometry, and pH monitoring. Treatment varies from dietary modifications and medications to surgery depending on the condition.

    Did you know? The large intestine absorbs water, and the remaining material is turned into waste for elimination.