The spine is a column of 33 vertebrae, linked by discs, small joints and ligaments, and moved and supported by layers of muscle. It protects the spinal cord, carries the weight of the upper body and lets you bend, twist and turn. It is far more robust than its reputation: the spine is built to move and load in many positions, and most back pain is not caused by damage to it.
The regions
| Region | Vertebrae | What it does |
|---|---|---|
| Neck (cervical) | 7 | Supports and moves the head; the most mobile region. See the cervical spine |
| Upper back (thoracic) | 12 | Attached to the ribs; stable, with rotation. See the thoracic spine |
| Lower back (lumbar) | 5 | Carries the most load; bending and lifting. See the lumbar spine |
| Sacrum | 5, fused | Links the spine to the pelvis |
| Coccyx (tailbone) | 3 to 5, fused | Attachment for muscles and ligaments |
Seen from the side, the regions form gentle curves that help absorb load. Their size varies a lot between healthy people. See spinal curves.
The parts
- Vertebrae: the bones, each with a solid body at the front and a ring at the back that surrounds the spinal cord.
- Intervertebral discs: tough rings with a softer centre between the vertebral bodies; they spread load and allow movement. See the intervertebral disc.
- Facet joints: small paired joints at the back of each level that guide movement. See facet joints.
- Ligaments: strong bands that hold the column together.
- Spinal cord and nerves: the cord runs down the canal and nerve roots leave between the vertebrae. See spinal nerves.
- Muscles: deep muscles that control each segment and larger ones that move and support the trunk. See core muscles and erector spinae.
Strong, not fragile
A 2019 review of the evidence on posture describes the spine as a robust, adaptable structure that can safely move and load in a variety of postures.1 Spinal curves vary naturally, and no single curvature is strongly associated with pain.
For nearly everyone with back pain, no specific damaged structure can be identified, and only a small share has a serious cause such as a fracture, infection or cancer.3
Why scans can mislead
Many changes in the spine are part of normal ageing. In people without back pain, disc degeneration was seen in 37% of 20-year-olds and 96% of 80-year-olds.2 A scan shows structure, not pain. See how the spine changes with age.
What keeps a spine healthy
Movement, strength and load that builds up gradually. See load tolerance and exercise therapy.
Footnotes
General information, not medical advice. Every claim carries its source; where the evidence is thin, the page says so.Editorial policy · How we grade evidence · All sources · Disclaimer