tentorium

/T EH1 N T AO1 R IY0 AH0 M/
noun
  1. 1

    The framework of internal supports (a false endoskeleton) within an arthropod head, formed by ingrowths of the exoskeleton called apophyses.

  2. 2

    The tentorium cerebelli, an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes.

Source: https://en.wiktionary.org/wiki/tentorium