The optic chiasm or optic chiasma ( Greek χίασμα , `` crossing '' , from the Greek χιάζω ` to mark with an X ' , after the Greek letter ' Χ ' , chi ) is the part of the brain where the optic nerves ( CN II ) partially cross .
The optic chiasma , or ` optic chiasm ' , is the part of the brain where the optic nerves ( CN II ) partially cross .