metacarpal vein vs vena

metacarpal vein and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
metacarpal vein	Yes	No	No	No
vena	Yes	No	No	No

As nouns, vena is a hypernym of metacarpal vein; that is, vena is a word with a broader meaning than metacarpal vein:

metacarpal vein: dorsal and palmar veins of the hand
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of metacarpal vein include vein, venous blood vessel.

metacarpal vein (noun)	vena (noun)
dorsal and palmar veins of the hand	a blood vessel that carries blood from the capillaries toward the heart