וַיַּ֗רְא כִּ֣י לֹ֤א יָכֹל֙ ל֔וֹ וַיִּגַּ֖ע בְּכַף־יְרֵכ֑וֹ וַתֵּ֙קַע֙ כַּף־יֶ֣רֶךְ יַעֲקֹ֔ב בְּהֵֽאָבְק֖וֹ עִמּֽוֹ׃
And he saw that he could not prevail against him, and he touched the hollow of his thigh; and the hollow of Yaakov’s thigh was strained as he wrestled with him.
Torah Temimah points to Chullin 91a (continuation on the injury).
ויגע בכף ירכו — תנא: במקום שחיטת בהמה נגע בו.
“And he touched the hollow of his thigh” — A Tanna taught: He touched him in the place of the slaughter of an animal.
The Gemara identifies the precise location of the injury that later becomes the source of the gid hanasheh prohibition.
Derash on the location of the touch (Bavli).
The angel struck Yaakov at the place corresponding to the sciatic nerve of an animal.