Decussation

Decussation is used in biological contexts to describe a crossing.

Examples include:
 * In the brain
 * Decussation of the pyramids
 * Ventral supraoptic decussation
 * Decussation of optic nerve fibres to combine retinal information from both eyes
 * In phyllotaxis when an opposite pattern of leaves has successive leaf pairs that are perpendicular, it is called decussate.