top of the head; crown; parietal region
Anatomical term for the uppermost part of the head. In everyday contexts, 頭のてっぺん is more common.
I feel a slight pain on the top of my head.
This hat is a little tight at the crown.
後頭部 is the back of the head, whereas 頭頂部 is specifically the crown/top of the head.
Compound of 頭頂 (とうちょう, 'top of the head') + 部 (ぶ, 'part, region').