Oesophagus

The pharynx

Having entered through the mouth, food passes back to the pharynx, via a route also taken by liquids and air. The pharyngeal constrictor muscles that form the outer layer of the pharynx enable food to be propelled downwards into the oesophagus.

 

The oesophagus

This muscular tube is approximately 25 cm in length and 2 to 2.5 cm in diameter, links the pharynx to the stomach and has the purpose of moving the food downwards, thanks to peristalsis, to the cardia, the opening that connects it to the stomach. This unique digestive function is accomplished during the process of swallowing, thanks to the relaxation of the upper oesophageal sphincter (the circular muscle that surrounds the oesophagus) and the closure of the larynx, at the entrance to the respiratory tract, by the epiglottis. Following a passage of 4 to 8 seconds for solids and 1 to 2 seconds for liquids, the food reaches the lower oesophageal sphincter, which relaxes in order to facilitate passage into the stomach.

It is worth noting that while the mouth is involved in both breathing and swallowing, these two processes cannot take place at the same time, in order to prevent food from entering our lungs.