Editorial Summation

Abstract

While the term ‘sphincter’ has been generally used in this book for junction areas between different organs of the gastrointestinal tract, it is accepted that alternative terms such as ‘pylorus’ and ‘valve’ have also been used to describe some of these specialised areas. None of these terms, however, seems totally applicable. In so far as flow through these regions is usually unidirectional, the concept of a valve is sound, but it has the disadvantage that it conceals the fact that some movement of content can occur normally in an orad direction. In addition, the mechanistic concept of a valve underestimates the innate variability of activity that some of these areas demonstrate. The term ‘pylorus’ literally means a door-keeper. While it can be employed broadly to describe the function of all these specialised areas, because it is used specifically to describe the gastric outlet its application to any of the other areas is precluded. This therefore appears to limit these areas to being grouped together as ‘sphincters’.