First verse - Kaminoku

…While we're at it, let's also note how each phrase is called. 5･7･5･7･7 is divided into the top three phrases (5･7･5) and the bottom two phrases (7･7), with the former called the "kami-no-ku" (upper verse) and the latter called the "shimonoku" (lower verse). The first phrase (5) is called the first verse, head verse, or opening verse, the second phrase (7) is called the chest verse, the third phrase (5) is called the lower verse, the final verse, or closing verse. …

*Some of the terminology explanations that mention "Kamiku" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ついでに，各句の呼び方も記しておこう。5･7･5･7･7を上3句(5･7･5)と下2句(7･7)とに分け，前者を〈上句（かみのく）〉，後者を〈下句（しものく）〉と呼ぶ。第1句(5)を初句，頭句，起句，第2句(7)を胸句，第3句(5)を腰句，第5句を結句，尾句，落句などと呼んでいる。…

※「上句」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報