Each vertebra features a projection of bone from the arch of the vertebra toward the ~posterior~ (rear). This projection, located at the apex of the arch and bordered on the arch by the laminae, is known as the |spinous process|. It is the series of these ~processes~ which is visible as the bumps beneath the skin on the back. The |spinous process| serves as an anchor point for ~ligaments~ which help control the flexibility of the |spine|. The |vertebrae| feature different types of |spinous processes|. Typical |cervical vertebrae| have bifid (forked) |spinous processes|, with the exception of the |atlas| (first cervical vertebra) which has no |spinous process|. |Thoracic vertebrae| generally have a single ~tubercle~ (that is, they are not forked), and point downward as well as back. The |lumbar vertebrae| feature |spinous processes| which are rectangular or hatchet-shaped and have a section which points back and one which points down. The |spinous processes| of the |sacrum| and |coccyx| are generally fused together, to form a ridge called, in the |sacrum|, the sacral crest. Often, the |coccygeal| |vertebrae| (fused or not) show no evidence of any ridge, crest, or |spinous process|.
