Anatomy of the Spine

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Anatomy of the spine

The spine is one of the most important parts of your body. It allows you to stand up and keep yourself upright, to move and bend. Your spine gives your body structure and support. It also protects your spinal cord, the column of nerves that connects your brain with the rest of your body, allowing you to control your movements, and allowing your organs to function.

Your spine is made of 33 bony elements called vertebrae, which are connected to one another like links in a chain. The natural curves in the spine, kyphotic and lordotic, provide elasticity in distributing body weight and sustain axial loads during movement, much like a shock-absorbing spring.

The spinal column consists of:

  • The upper part of the spine known as the neck – includes seven cervical vertebrae (numbered C1 to C7);
  • The central (or, upper back) part of the spine – includes twelve thoracic vertebrae (numbered T1 to T12);
  • The lower portion of the spine, known as the lumbar spine – usually consists of five vertebras, numbered L1-L5 (Some people may have six lumbar vertebrae; this is normal); 
  • Five bones (that are joined, or “fused,” together in adults) to form the bony sacrum; 
  • Three to five bones fused together to form the coccyx or tailbone.

The vertebrae protect and support the spinal cord, and bear most of the weight put on your spine. Each vertebra is made up of a large bone called the vertebral body, and the lamina, which extends from the vertebral body and forms a ring to enclose and protect the spinal cord. The lamina includes a) the spinous process, which is the bone you feel when you run your hand down someone’s back, b) two transverse processes – where the back muscles connect to the vertebras, and c) the pedicle that connects the two sides of the lamina. The spinal cord runs through the long hollow tube formed by the opening at the center of all vertebrae.

The spine branches off into thirty-one pairs of nerve roots. These roots exit the spine on both sides of each vertebra. Between each vertebra is a soft, gel-like cushion called a disc. The disc helps absorb pressure and keeps the bones from rubbing against each other. Each vertebra is held to the others by groups of ligaments. There are also tendons in the spine, which connect muscles to the vertebrae. Like other parts of the body such as the knee or elbow, the spinal column has joints, called facets, which link the vertebrae together and give them the flexibility to move against each other.

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