Yes, ZYGOMA is a Scrabble word!

Letter values in Scrabble US: Z 10, Y 4, G 2, O 1, M 3, A 1.

Is it a valid word?

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

the slender arch formed by the temporal process of the cheekbone that bridges to the zygomatic process of the temporal bone

Also: zygomatic arch, arcus zygomaticus.