The Human Spine - Vertebra and Facet Joints

The human spine is made up of large bones called vertebra.

diagram of human spine

The vertebral body is a largish, flat area and makes up the bulk of the bone.
The spinal disc sits on top of this area and acts as a really efficient cushion between the bones.
The bony part that you can see and feel at the back of your spine is called the spinous process.
The vertebra also has bony parts that stick out at the sides, these are called transverse processes. You cant see these although your physical therapist or chiropractor can feel them.
These bony parts together make a ring of bone, an triangular type space in the middle of the bone. That space is called the spinal canal and the spinal cord runs down through this space, nicely protected by bone on all sides.
Each vertebra overlaps the next at the back and these areas of overlap form joints. There are two joints for each vertebra, one on either side and they are called facet joints.
These facet joints allow movement between the vertebra, they are the inks in the chain. without them we would be stiff and unable to move our spines. All spinal movement takes place at these joints.
I often describe these joints to my patients as very like finger joints, allowing movements in certain directions.
In the lower back the main movements that take place are forward bend, backward bend, and sideways bending. There is not much rotation or twisting in the lower part of the back - that mostly takes place a bit higher up. More on these spinal movements with diagrams.

02-Nov-2009