Variability of the morphology of gastrocnemius muscle in an African population

Abstract

Gastrocnemius morphological status is often designated as being bipennate. Its robustness in humans is a feature that accompanies the human mode of locomotion. The three-headed variant has often been reported, but paucity of information exists within the Nigerian population as regards gastrocnemius morphological variability. We therefore currently aim to determine the pattern of occurrence of variations of the muscle in both legs of thirty cadavers in four Anatomy laboratories of Universities in Southwestern part of Nigeria. Our current study shows that the multi-headed variants (three and four-headed) are more dominant. A minority (35%) of the legs had two-headed gastrocnemius muscle, 13.3% had three-headed gastrocnemius while 51.7% had four-headed gastrocnemius muscle. This study provides a careful description of the gastrocnemius muscle in the studied population and also sheds light on the embryological and clinical implications of the findings. The knowledge of variant gastrocnemius anatomy will aid understanding of popliteal surface anatomy, palpation of popliteal arterial pulse, popliteal nerve block and the assessment of gastrocnemius muscle for autografting. The additional variant heads also bear evolutionary importance.

Keywords: Gastrocnemius; Multi-Pinnate; Popliteal Entrapment Syndrome; Variations; Four-Headed, Third Head Of Gastrocnemius