nape of the neck; back of the neck; scruff of the neck
Refers to the back of the neck, often in contexts of tension, touch, or grabbing someone by the scruff.
My neck is stiff.
He grabbed the cat by the scruff of the neck.
首筋 covers the whole neck area including the sides and front, while うなじ specifically refers to the back of the neck.
首筋 refers to the nape of the neck as a part of the body, whereas 襟元 focuses on the clothing area around the neck.
Standard kanji spelling; high frequency in news and general usage.
Mixed kanji-kana spelling; sometimes used for readability or when the second kanji is less familiar.
Rarely used kanji form; 頸 is a non-jōyō kanji for 'neck'.
Rarely used kanji form; 頚 is a variant of 頸.
Compound of 首 (kubi, 'neck') + 筋 (suji, 'line, muscle, sinew'). The reading くびすじ is a straightforward combination of the kun'yomi readings of the two kanji.