Yes, SEGMENTAL is a Scrabble word!

Letter values in Scrabble US: S 1, E 1, G 2, M 3, E 1, N 1, T 1, A 1, L 1.

Is it a valid word?

SEGMENTAL is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

divided or organized into speech segments or isolable speech sounds
having the body divided into successive metameres or segments, as in earthworms or lobsters