In human anatomy, the adult spinal column contains 33 vertebrae when fused vertebrae are counted individually.
The standard developmental count is seven cervical, twelve thoracic, five lumbar, five sacral and four coccygeal vertebrae. The five sacral vertebrae fuse to form the sacrum, while the four coccygeal vertebrae usually fuse into the coccyx. This produces 24 movable vertebrae plus the fused segments.
People often see the number 26 in anatomy references because that count treats the sacrum and coccyx as single bones: 24 separate vertebrae, plus two fused structures. Both numbers can therefore appear correct, but they answer different counting questions.
The vertebral column supports the trunk, protects the spinal cord and helps distribute loads through the pelvis. Its curves are not simply straight stacks; cervical and lumbar lordoses and thoracic and sacral kyphoses help with balance and shock distribution. Individual variation, especially in the coccyx, can affect the exact count.