How many bones comprise the human spine?

How many bones comprise the human spine?

• A. 24
• B. 33
• C. 26
• D. 30

Answer: (B)

The number comes from counting all the vertebral segments that make up the spine. There are 24 movable vertebrae: 7 cervical, 12 thoracic, and 5 lumbar. The sacrum is formed by the fusion of 5 sacral vertebrae, and the coccyx is formed by the fusion of 4 coccygeal vertebrae. If you count each original segment as its own bone, you have 24 + 5 + 4 = 33 bones. Some references simplify this to 26 by counting the fused sacrum and coccyx as single bones, but the 33-count reflects counting each vertebral segment before fusion.

The number comes from counting all the vertebral segments that make up the spine. There are 24 movable vertebrae: 7 cervical, 12 thoracic, and 5 lumbar. The sacrum is formed by the fusion of 5 sacral vertebrae, and the coccyx is formed by the fusion of 4 coccygeal vertebrae. If you count each original segment as its own bone, you have 24 + 5 + 4 = 33 bones. Some references simplify this to 26 by counting the fused sacrum and coccyx as single bones, but the 33-count reflects counting each vertebral segment before fusion.