tylion

tyl·i·on

, pl.

tyl·i·a

(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

/tyl·i·on/ (til´e-on) a point on anterior edge of the optic groove in the median line.

tylion

(tĭl′ē-ŏn) [Gr. tyleion, knot]
The point at the middle of the anterior edge of the optic groove.