The plural of gastrocnemius, referring to both calf muscles (one on each leg).
From Latin plural form of 'gastrocnemius', using the '-i' ending common in Latinized anatomical terminology. Medical Latin preserves classical plural forms even in modern English.
Medical terminology preserves Latin and Greek plurals like 'gastrocnemii,' which is why doctors might say 'both gastrocnemii' instead of 'both gastrocnemius muscles'—it's a linguistic fossil from the language of medicine.
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