(til'ē-on, -lē-ă; tī'lē-on), A craniometric point at the middle of the anterior edge of the prechiasmatic sulcus. [G. a small pin, dim. of tylē, a lump]
tylion
(tĭl′ē-ŏn) [Gr. tyleion, knot] The point at the middle of the anterior edge of the optic groove.