The esophagus is an organ in the digestive system. It is part of the gastrointestinal (GI) tract, which is the tube that goes from the mouth to the anus. The GI tract includes the esophagus, stomach, small intestine and large intestine. Other organs of the digestive system include the liver, gallbladder and pancreas.
The esophagus is a hollow, muscular tube that allows food to pass from the mouth to the stomach. The esophagus is 25–33 cm (10–13 inches) long. It begins in the throat (pharynx) and connects to the stomach. It is less than 2.5 cm (1 inch) in diameter at its narrowest part. It lies behind the windpipe (trachea) and in front of the backbone (spine) inside the chest cavity.
A ring of muscle fibres form the upper esophageal sphincter, which detects food and liquids in the back of the throat and controls the passage of food into the esophagus when a person swallows. The wall of the esophagus includes 2 strong muscle layers that contract to help push food along (peristalsis) until it reaches the stomach. At the bottom of the esophagus there is another ring of muscle fibres that form the lower esophageal sphincter (also known as the cardiac sphincter).The area where the esophagus joins the stomach is called the gastroesophageal (GE) junction.
There are a number of lymph nodes in and around the esophagus. Lymph nodes are small bean-shaped glands that fight infection. They are connected by a network of lymph vessels.
The esophagus is divided into 3 regions:
There are 3 tissue layers in the esophagus:
Unlike most of the gastrointestinal tract, the esophagus is not covered by serosa. A different outer layer of connective tissue, called the adventitia, loosely supports and covers the esophagus instead. Only the abdominal portion of the esophagus is covered by peritoneumperitoneumThe membrane that lines the walls of the abdomen and pelvis (parietal peritoneum), and covers and supports most of the abdominal organs (visceral peritoneum)..
Although the esophagus is part of the digestive system, it actually does not play a role in digestion. However, it is an important organ within the GI tract. When a person swallows, the muscular walls of the esophagus contract (tighten) and push food and fluids from the mouth into the stomach for digestion. Glands in the submucosa layer produce mucus, which helps keep the inside of the esophagus moist and provides lubrication for swallowing.
At the GE junction, where the esophagus and stomach join, the lower esophageal sphincter acts like a valve to control the passage of food into the stomach. When it opens, the valve lets food into the stomach. When closed, it prevents the stomach contents from going back into the esophagus.