Articulation is just a fancy word for joint. To disarticulate is to separate at the joint. We often think of the skull as one or two bones: the skull and the jaw. It is actually a complex integration of many bones. This is evident in newborns. Have you noticed the "soft spots?" That's soft cartilage that allows for the skull to grow and make more space for the developing brain. Over time this cartilage ossifies to become bone. These bones meet and fuse to create non-mobile joints called sutures.