Decussation

Decussation (or decussatio) is used in biological contexts to describe a crossing.^[1]

Examples include:

In the brain, where nerve fibers obliquely cross from one lateral part to the other, that is to say they cross at a level other than their origin. See Decussation of the pyramids.
In phyllotaxis when an opposite pattern of leaves has successive leaf pairs that are perpendicular, it is called decussate.
In tooth enamel, where bundles of rods (rods are the basic structural unit of enamel) cross each other as they travel from the enamel-dentine junction to the outer enamel surface (or near to it).

References