يفَخَ يَيْفَخ، يَفْخًا، فهو يافِخ، والمفعول مَيْفوخ

ضَرَبه فأصابَ يافوخَه؛ أي : مُلتقَى مُقدَّم رأسِه مع مُؤخَّره

🇬🇧 Translation:

He struck him on the crown of his head (the junction of the front and back of the head).