Esophagus

The esophagus or oesophagus, sometimes known as the gullet, is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. In humans the esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra. The esophagus passes through a hole in the thoracic diaphragm called the esophageal hiatus. It is usually 25-30 cm long which connects the mouth to the stomach. It is divided into cervical, thoracic, and abdominal parts.

Functions of the esophagus

Food is passed through the esophagus by using the process of peristalsis. Specifically, it connects the pharynx, which is the body cavity that is common to the digestive factory and respiratory system with the stomach, where the second stage of digestion is initiated.

The esophagus is lined with mucous membrane, and is more deeply lined with muscle that acts with peristaltic action to move swallowed food down to the stomach.

Histology

The layers of the esophagus are as follows:

• mucosa
• • nonkeratinized stratified squamous epithelium: is rapidly turned over, and serves a protective effect due to the high volume transit of food, saliva and mucus.
  • lamina propria: sparse.
  • muscularis mucosae: smooth muscle
• submucosa: Contains the mucous secreting glands (esophageal glands), and connective structures termed papillae.
• muscularis externa (or "muscularis propria"): composition varies in different parts of the esophagus, to correspond with the conscious control over swallowin g in the upper portions and the autonomic control in the lower portions:
  • upper third, or superior part: striated muscle
  • middle third, smooth muscle and striated muscle,
  • inferior third: predominantly smooth muscle.
• adventitia

Gastroesophageal junction

The junction between the esophagus and the stomach (the gastroesophageal junction or GE junction) is not actually considered a valve, although it is sometimes called the cardiac sphincter, cardia or cardias, but is actually more of a stricture.

Additional images

H&E stain of biopsy of normal esophagus showing the stratified squamous cell epithelium	Layers of the esophagus.	Mid-esophageal mass	Stomach
Accessory digestive system.	Organs of the digestive tract.	Esophagus	Section of the neck at about the level of the sixth cervical vertebra.
Transverse section of thorax, showing relations of pulmonary artery.	Sagittal section of nose mouth, pharynx, and larynx.	The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind. |	Section of the human esophagus. Moderately magnified.
Microscopic shot of a cross section of human gastro-esophageal junction wall.