Vertebral column from neck to tailbone:
Cervical (7, neck) → Thoracic (12, chest) → Lumbar (5, lower back)
→ Sacral (5 fused, pelvis) → Coccygeal (4 fused, tailbone)
Answer: Cervical, Thoracic, Lumbar, Sacral, Coccygeal
The vertebral column (spine/backbone) is a flexible bony column consisting of 33 vertebrae in 5 regions: cervical (7), thoracic (12), lumbar (5), sacral (5, fused), coccygeal (4, fused). It protects the spinal cord, supports the skull and trunk, and allows movement.
Cervical vertebrae: smallest, transverse foramina for vertebral arteries, C1 (atlas), C2 (axis). Thoracic: articulate with ribs, larger spinous processes. Lumbar: largest/strongest, support maximum weight, no transverse foramina. Sacrum: 5 fused, wedge-shaped, articulates with ilium. Coccyx: 4 fused, vestigial tail.
Between adjacent vertebrae (C2 to sacrum) are fibrocartilaginous intervertebral discs: nucleus pulposus (central, gel-like, absorbs shock) + annulus fibrosus (outer fibrous ring). Herniated (slipped) disc: nucleus pulposus protrudes through annulus, compressing spinal nerve roots causing pain, numbness, or weakness.
L4-L5 and L5-S1 are most common sites for disc herniation (lower back pain, sciatica). Cervical spine fractures are most common at C5-C6. Osteoporosis commonly causes thoracic vertebral compression fractures in elderly.
The adult human vertebral column has 26 bones, formed from 33 in the embryo. The regions are cervical 7, thoracic 12, lumbar 5, sacral 1 (fused from 5) and coccygeal 1 (fused from 4). The cervical count of 7 is constant across almost all mammals, including the giraffe — its neck vertebrae are simply much longer, not more numerous, which is a favourite one-mark question.
The axial skeleton has 80 bones: skull 22, hyoid 1, ear ossicles 6, vertebral column 26, sternum 1 and ribs 24. The appendicular skeleton has 126: limb bones plus the pectoral and pelvic girdles. Together they make 206 in the adult. Infants have around 270, the number falling as bones fuse during growth — which is why the adult figure is the one asked for.
Of the 12 pairs of ribs, the first 7 are true ribs attached directly to the sternum by hyaline cartilage, pairs 8 to 10 are false ribs attached indirectly through the seventh pair, and pairs 11 and 12 are floating ribs with no ventral attachment at all. Joints are classified as fibrous and immovable, as in the skull sutures; cartilaginous with limited movement, as between vertebrae; and synovial and freely movable, as in the knee and shoulder.
Giving 33 as the adult vertebral count. The embryo has 33; fusion of the sacral and coccygeal vertebrae reduces this to 26 in the adult.
Counting ribs as 12 rather than 24. There are 12 pairs, so 24 individual bones in the total of 206.