Anatomy word of the month: Decussation

“To make an X” (Latin). A decussation is an intersection of pathways in the form of an X. Most nerve pathways between our brain and spinal cord cross over at some point. This accounts for why each side of our brain (two cerebral hemispheres) has control over the opposite side of our body. In anatomical language this is called a contralateral relationship (opposite sides). This information is useful in determining the location of a stroke. Paralysis of the right side of the body would mean that a cerebrovascular accident (CVA), the fancier name for stroke, had occurred in the left cerebral hemisphere. “Decem” is the Latin word for the number ten, or “deca” in Greek. Hence, decussation literally means to draw the Roman numeral for ten.  December is also the tenth month of an early Roman calendar.