What are vertebrae?
The individual bones stacked to form the spine. One is a vertebra. Two or more are vertebrae (VER-tuh-bray). There are 33 in a full spine, though the bottom ones fuse.
One vertebra, many vertebrae: the plural ends in 'ay', like 'hooray, more of them'.
The vertebrae are irregular bones: complex shapes that fit no other group. They are the classic example.
What are the five regions of the spine?
| Region | Where | Vertebrae | Word origin |
|---|---|---|---|
| Cervical spine (SER-vih-kul) | The neck. It holds up and moves your head. | 7 | cervical = of the neck |
| Thoracic spine (thor-ASS-ik) | The upper and middle back. Each of its vertebrae connects to a pair of ribs. | 12 | thoracic = of the chest |
| Lumbar spine (LUM-bar) | The lower back. Its vertebrae are the largest in the spine because they carry the most weight. | 5 | lumbar = of the loin |
| Sacrum (SAY-krum) | Five vertebrae fused into one triangle of bone that locks the spine into the pelvis | 5, fused | sacrum = sacred bone |
| Coccyx (KOK-siks) | The tailbone, at the very bottom of the spine | Usually 4, fused | coccyx = cuckoo |
How many vertebrae are in each region?
- Cervical: 7. Almost every mammal has seven neck vertebrae, even a giraffe.
- Thoracic: 12, one for each pair of ribs.
- Lumbar: 5, the biggest vertebrae in the spine.
Memory hook: breakfast at 7, lunch at 12, dinner at 5. Cervical 7, thoracic 12, lumbar 5.
What is lordosis?
Lordosis (lor-DOH-siss) is the natural inward curve of the neck and lower back. Too much in the lower back tips the pelvis forward. The word means bent backwards. Lordosis is the hollow: L for lower back, L for lordosis.
What is kyphosis?
Kyphosis (ky-FOH-siss) is the natural outward curve of the upper back. Too much is the rounded hunch you see after years at a desk. Kyphos is Greek for hump.
What is scoliosis?
Scoliosis (skoh-lee-OH-siss) is a sideways curve of the spine, seen from behind. Unlike lordosis and kyphosis, it isn't part of the spine's normal shape. The word means crooked. S for sideways.
Which muscle holds the spine upright?
Erector spinae runs either side of the spine. It extends the spine and holds it upright.
What joints are in the spine?
- The joints between vertebrae are cartilaginous joints. They move slightly.
- The top two vertebrae form a pivot joint that lets you shake your head.