最さい長ちょう筋きんMeanings1nounlongissimus muscleanatomyAnatomical term for the longissimus muscle, part of the erector spinae group. Used in medical and anatomical contexts.最さい長ちょう筋きんは脊せき柱ちゅう起き立りつ筋きんの一いち部ぶです。The longissimus muscle is part of the erector spinae.