noun
spine; line of the back; backbone line
Refers to the vertical line along the back or spine, especially in posture expressions such as 背筋を伸ばす.
背筋を伸ばして椅子に座った。
I sat in the chair with my back straight.
怖い話を聞いて背筋が寒くなった。
Hearing the scary story sent a chill down my spine.
noun
back seam; seam down the back of clothing
Clothing and sewing use: the seam or line running down the back of a garment.
ジャケットの背筋の縫い目が少し曲がっている。
The seam down the back of the jacket is slightly crooked.
More directly means the backbone or vertebral column as a body part; 背筋 often focuses on the line of the back or posture.
Means posture or bearing in general; 背筋 appears in expressions like 背筋を伸ばす to describe straightening the back.
General word for a seam or stitch line; the clothing sense of 背筋 specifically refers to the seam or line down the back.
A compound of 背, meaning the back, and 筋, meaning a line, strand, or streak; the spelling reflects the idea of the line running along the back.