Anatomical insights into a five-bellied gastrocnemius muscle: a case report.

The gastrocnemius (GM), a superficial posterior leg muscle, consists of medial and lateral heads and drives ankle plantarflexion and knee flexion. The morphological variability of this muscle has been extensively studied, especially the presence of a third head. Here, a novel five-headed configuration of the GM was identified during the cadaveric dissection of a 30-year-old male. The right GM exhibited five distinct heads, each with independent vascular and neural supply, whereas the contralateral limb displayed a three-headed configuration including a gastrocnemius tertius (GT). Detailed morphometric assessment was performed, and the developmental proximal attachment of the supernumerary heads and its clinical implications were discussed. Although often asymptomatic, these variants can alter biomechanics, narrow the popliteal corridor, and increase the risk of vascular or musculotendinous injury and misdiagnosis. Recognition of complex GM anatomy is therefore essential for surgeons and radiologists. Thus, this case highlights the developmental variability of the posterior leg compartment and underscores the importance of recognizing rare GM variants to ensure accurate diagnosis and safe clinical management.