Answer: 33 (7C + 12T + 5L + 5S + 4Coccyx unfused).
- A 26 (7C + 12T + 5L + 5S + 4Coccyx fused)
- B 22
- C 30
- D 33 (7C + 12T + 5L + 5S + 4Coccyx unfused)
Correct answer: D. 33 (7C + 12T + 5L + 5S + 4Coccyx unfused)
Explanation: The vertebral column has 33 vertebrae in childhood: 7 cervical (C1-C7), 12 thoracic (T<sub>1</sub>-T<sub>12</sub>), 5 lumbar (L1-L5), 5 sacral (fuse to form sacrum), 4 coccygeal (fuse to form coccyx). In adults, 26 bones remain after fusion of sacral and coccygeal vertebrae.
A sarcomere (Z line to Z line): during contraction the I band and H zone shorten as thin filaments slide over thick, while the A band stays the same length. Image: SlothMcCarty, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Types of movement, muscle contraction, skeletal system, joints, and disorders. Important for Class 11 and NEET.