Zygapophysis: growths, yokes and joints
What are they? The bones in our spine (vertebrae) have growths that stick out and join to other vertebrae above and below. These growths are called zygapophyses — the singular is zygapophysis. Why the name? Because they link vertebrae, they are named after the Greek word zygon , meaning yoke. The rest of the name comes from apo , meaning from, and physis , which means growth. What do they do? They protect the spine by making it more stable. Each zygapophysis locks onto the adjacent vertebra at a facet joint, of which vertebrae typically have four. These joints are positioned at each level in the spine to ensure the vertebrae rotate just as much as needed, and also don’t slip forward over each other. For example, because we need to turn our head, they allow much more rotation in the bones in our neck than in the lower back.