疼痛集中在我的小腿后部。

The pain is localized in my ___calf.

马拉松期间，我的左小腿后部突然一阵剧烈抽筋。

A sharp cramp shot through my left ___calf during the marathon.

她轻轻按摩酸痛的小腿后部肌肉。

She gently massaged the sore ___calf muscle.