The front part of each of the vertebrae is called the vertebral body. There are a total of 23 elastic spinal discs spread out between the vertebrae – except for between the skull and the first cervical (neck) vertebra, and between the first and second cervical vertebrae. The sacrum and the tailbone can't be moved, and are made up only of bone.
Each spinal disc consists of a soft gel-like core that is surrounded by a tough, multi-layered case made of fibrous cartilage. They keep the spine flexible so that we can lean over and rotate our upper body. They also act as shock-absorbers when we run or jump, for instance.
When we put pressure on our spine, the spinal discs release fluid and become thinner (“compress”); when the pressure is relieved, they absorb fluid again and become thicker (“decompress”). Because we usually put more pressure on our spine during the day and relieve the pressure at night, we are around 1.5 to 2 centimeters shorter (about 0.6 to 0.8 inches shorter) by the end of the day.
Signs of wear and tear may start appearing after many years. As we get older, the spinal discs become narrower, the vertebrae move closer to each other, and the spine becomes more curved. Because of this, older people are usually a few centimeters shorter than they used to be when they were younger. Wear and tear on the vertebrae and spinal discs (degeneration of the spine) is also known as spondylosis. Many people have degenerative changes in their spine but they don't always have back pain or other symptoms. So when people have these symptoms, it usually isn’t absolutely clear whether they are caused by degeneration of the spine.
Apart from the first two vertebrae in the neck, as well as the sacrum and tailbone, all of our vertebrae have a vertebral body at the front and a "spinous process" at the back. Both parts are connected by the vertebral arch, which forms a space in the middle called the vertebral foramen. These spaces align to form the spinal canal, which surrounds the spinal cord.