The Prevalence of Gantzer's Muscle in the Israeli Population: A Cadaver-based Anatomical Study

Introduction: The Gantzer muscle (GM) is an anatomical variant of the human upper extremity. Its two bellies - the accessory muscle of the flexor digitorum profundus (AFDP) and the accessory flexor policis longus (AFPL) have been described in several populations. Despite the GM's commonality, little consideration has been given to its origin, possible function, or clinical significance. Our study aimed to assess the prevalence of the GM in the local population of Israel, to characterize it demographically, and to define side preference if present. Materials and Methods: We examined cadavers of individuals of Israeli nationality (n = 88, n = 49 females; n = 39 males; all >60 years old). Our study was performed at the Department of Anatomy and Anthropology, Sackler School of Medicine, Tel Aviv University. Results: Gantzer's muscle (either AFDP or AFPL or both) was present in 61 out of 88 cadavers (69.3%). Prevalence of the AFPL was 60.2%, found in 53 out of 88 cadavers dissected. In 34.1% of cadavers, the muscle was present bilaterally. Among the unilateral cases (n = 23), prevalence was the same for the right and left sides (χ² =1.087, df = 1, P = 0.297). Conclusions: Our findings demonstrate a high prevalence of Gantzer's muscle in the Israeli population. We found at least one of the accessory muscles in 69.3% of cadavers assessed. The course of the GM most commonly found was as an accessory muscle inserted into the flexor pollicis longus (FPL) tendon; thus, we believe the GM may contribute to the precision of function of the thumb as a fine tuner to FPL muscle function.