What is istmo de las fauces?

As an AI language model, I don't have any context as to which istmo de las fauces you are referring to.

But if you are talking about the isthmus of the fauces, also known as the pharyngeal isthmus, it is a narrow passage between the oral cavity and the pharynx, located in the back of the throat. It is a key anatomical structure involved in the process of swallowing and also plays an important role in respiratory functions. The isthmus of the fauces is composed of a group of muscles, including the palatoglossus, palatopharyngeus, and stylopharyngeus muscles, which work together to control the opening and closing of the passage during swallowing. Dysfunction of these muscles can lead to swallowing difficulties and other related disorders.