One of the more moderately annoying things about learning Russian, especially if you already know some of another Slavic language, is that it’s riddled with doublets of native East Slavic words and OCS borrowings with slightly different meanings. So, e.g., здоровый means “healthy” while здравый is “sane”; “head (adj.)” in the metaphorical sense of “principal” is головной or главный, but only the first has the literal anatomical meaning.