כְּ֭תֵפִי מִשִּׁכְמָ֣ה תִפּ֑וֹל וְ֝אֶזְרֹעִ֗י מִקָּנָ֥ה תִשָּׁבֵֽר׃
Then let my shoulder fall from the shoulder-blade, And mine arm be broken from the bone.
Rashi on Job
from its bone That is the upper bone, which is round as a reed (קנה), and because it is round as a reed, it is called so.