A rare anatomical variation of the origin and insertion of the extensor pollicis et indicis communis muscle

The extensor compartment of the forearm is a site with frequent anatomic variation that are encountered during examination with radiologic imaging, surgery, and general cadaver dissections. One such variation is the extensor pollicis et indicis communis (EPIC) which has a prevalence of 0.5 to 4% in the global population. Our group at PCOM South Georgia discovered this anatomical variation on a female cadaver of 58 years during a routine dissection of 12 cadavers obtained through the Body Donor Program at PCOM Georgia. The EPIC muscle was encountered unilaterally on the posterior aspect of the right forearm between the extensor pollicis longus and extensor indicis. The muscle belly has a proximal insertion on the proximal ½ of the ulna and a distal insertion on the proximal phalanx of the pollex as well as the indicis. This case study aims to describe this rare variation as knowledge of the extensor pollicis et indicis communis is paramount in avoiding and preventing injury during a surgical intervention of the hand and wrist