Absence of the extensor indicis muscle: a case report in a human cadaver

Abstract

Anatomical variations of upper limb muscles, although uncommon, are highly relevant findings for both surgical practice and anatomy education. The absence of the extensor indicis muscle is particularly rare, with a reported prevalence ranging from 0.5% to 3.5% in previous meta-analyses (Ma et al., 2021), and may directly impact tendon reconstruction procedures and functional assessment of the hand. This study aims to report a case of congenital absence of the extensor indicis muscle, identified during cadaveric dissection activities conducted by the Department of Anatomy at Faculdade Ciências Médicas de Minas Gerais, highlighting its potential clinical implications. A systematic dissection of the dorsal hand and forearm of a male adult cadaver was performed following standardized anatomical protocols. A complete absence of the extensor indicis muscle was observed on the left upper limb, with no other associated muscular anomalies. Morphological analysis indicated a congenital variation, not resulting from trauma or pathological processes. It is concluded that the recognition and documentation of such anatomical variations are fundamental both for medical education and for professionals dealing with interventions in the upper limb.