A button has several definitions in the field of medicine. One
definition is any structure, device, or lesion (an abnormal
change in tissue) that has the shape of a knob. The most
famous example of a normal bodily structure that can have the
shape of a button is the belly button. When on the body, button
structures are generally raised. Belly-buttons that are raised are
typically referred to as “outies” (a reference to it sticking out).
An abnormal area shaped like a button is a collar button lesion,
which is a type of small deep ulcer that has a narrow neck (said
to have a button neck appearance) and a button surface
A belly button.
FEATURED BOOK: What's Behind Your Belly Button

An ulcer is an open sore on the skin or on a mucous membrane. A mucous membrane is
one of four major types of thin sheets of tissue that line or cover various parts of the
body, such as the mouth and passages for breathing.

A button can also refer to a small device (which is shaped like a disk or a spool) used in
surgery to join two openings in the intestines, which allows blood to flow from one
opening to the other. The intestine is a tube shaped structure that is part of the digestive
tract. Lastly, a button can also refer to a lobule of a mammal's placenta (an organ in a
female that nourishes a baby during pregnancy). A lobule is a small mass of tissue that
various organs are made of. Button comes from the Old French word "bouton" which
means "to thrust."
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