Related for Chullin 181:37

אמר רבא אמר קרא

[which suggests] as when a person locks another [in his arms] and his [right] hand reaches the hollow of that other's right thigh.<span class="x" onmousemove="('comment',' So it was with Jacob, and it was his right thigh only that was injured.');">²⁰</span>

Maharam Schiff on Chullin