Applied Anatomy and Physiology of the Esophagus

Introduction

The esophagus is a muscular tube connecting the pharynx to the stomach, playing a crucial role in the transport of ingested food and liquids. Understanding its structural anatomy and histological features provides insights into its physiological functions.

Structural Anatomy of the Esophagus

Macroscopic Features

The esophagus measures approximately 25 cm in length and is divided into cervical, thoracic, and abdominal parts. It passes through the diaphragm at the esophageal hiatus and ends at the gastroesophageal junction.

Layers of the Esophagus

• Mucosa: Composed of stratified squamous epithelium, lamina propria, and muscularis mucosa.
• Submucosa: Contains connective tissue, blood vessels, and submucosal glands.
• Muscularis propria: Consists of both circular and longitudinal muscle layers, aiding peristalsis.
• Adventitia/Serosa: The outermost layer provides structural support.

Histological Features

The esophageal epithelium is primarily non-keratinized stratified squamous, which protects against mechanical stress. The muscular composition transitions from skeletal muscle in the upper third to smooth muscle in the lower third.

Physiological Functions

Swallowing Mechanism

The esophagus facilitates the passage of food via coordinated muscle contractions known as peristalsis.

Lower Esophageal Sphincter (LES)

Regulates the passage of food into the stomach and prevents reflux.

Clinical Significance

Understanding esophageal anatomy is crucial in diagnosing conditions such as gastroesophageal reflux disease (GERD) and esophageal cancer.