The function of oesophagus. - Practice Questions & MCQ

• It is a 25 cm long and narrow muscular tube that connects the pharynx to the stomach. 
• It is located posterior to the trachea and remains in a collapsed form when not engaged in swallowing due to longitudinal folds. This prevents the entry of air.
• To enter the abdomen, the oesophagus penetrates the diaphragm through an opening called the oesophageal hiatus.
• It bends sharply to open into the stomach. This bend prevents backflow of stomach contents into the oesophagus. 

Histology of Oesophagus

• The mucosa is made up of stratified squamous epithelium containing mucous glands.
• The muscularis layer changes according to the location: In the upper third of the oesophagus, the muscularis is skeletal muscle. 
• In the middle third, it is both skeletal and smooth muscle. In the lower third, it is smooth muscle.

Passage of Food through the Oesophagus

• The oesophagus conveys the food into the stomach through the peristalsis movement.
• Peristalsis is the series of wave contraction from one end to the other and is meant for pushing the food.
• The upper oesophageal sphincter controls the movement of food from the pharynx into the oesophagus.
• A muscular sphincter called the gastro-oesophageal or cardiac sphincter regulates the opening of the oesophagus into the stomach.
• It relaxes to let food pass into the stomach, and then contracts to prevent stomach acids from backing up into the oesophagus.
• When the gastro-oesophageal sphincter does not completely close, the stomach’s contents can reflux (that is, back up into the oesophagus), causing heartburn or gastroesophageal reflux disease (GERD).