Pterygia are 'winglike' triangular membranes occurring in the neck, eyes, knees, elbows, ankles or digits. [https://orcid.org/0000-0002-0736-9199]

A pterygium (pl.: pterygia or pterygiums) is any wing-like triangular membrane occurring in the neck, eyes, knees, elbows, ankles or digits. The term comes from the Greek word pterygion meaning "wing". .