noun
vein (visible under the skin); bulging vein
Refers to veins that are visible through the skin, often bluish. Commonly used for bulging veins on the forehead or temples when angry or straining.
怒ると、彼のこめかみに青筋が浮き出る。
When he gets angry, veins bulge on his temples.
手の甲の青筋が透けて見える。
The veins on the back of my hand are visible through the skin.
Rarely used kanji form; 青筋 is preferred.
血管 is the general medical term for blood vessel, while 青筋 specifically refers to visible, often bluish veins under the skin.
Compound of 青 (blue/green) and 筋 (line/muscle/vein), literally 'blue line', referring to the bluish appearance of veins under the skin.