endocranium

noun, plural en·do·cra·ni·a [en-doh-krey-nee-uh] /ˌɛn doʊˈkreɪ ni ə/. Anatomy.

1. the inner lining membrane of the skull; the dura mater.
2. the inside surface of the skull.

noun plural -nia (-nɪə)

1. anatomy the thick fibrous membrane that lines the cranial cavity and forms the outermost layer of the dura mater

n. pl. en•do•cra•ni•a (-nē-ə)

1. The outermost layer of the dura mater.
2. The inner surface of the skull.