A reverse form of Linburg-Comstock variation with comments on its etiology and demonstration of interactive 3D portable document format.

Purpose: Two most common variations of flexor pollicis longus include its accessory head and its connection with the flexor digitorum profundus of the index (Linburg-Comstock variation). In addition, while three-dimensional (3D) screening has widely been used in anatomical education, its use as reporting tool in anatomical research is still limited. The objective of this study is to report a previously unrecognized form of the accessory head of flexor pollicis longus, discuss the potential etiology of Linburg-Comstock variation, and pilot the 3D scanning of a large-scale anatomical structure.