Which of the following correctly lists the serial regions and vertebral counts in an adult human?

The correct option is Cervical 7, Thoracic 12, Lumbar 5, Sacral 1-fused, Coccygeal 1-fused.

Explanation

The vertebral column (spine) forms the central axis of the skeleton in vertebrates. In humans, it is differentiated into five distinct regions. While the number of vertebrae is 33 during embryonic development, fusion occurs in specific regions as the individual matures, resulting in a reduced bone count in the adult skeleton.

Detailed Analysis

The adult human vertebral column consists of 26 serially arranged bones categorized as follows:

• Cervical Vertebrae (7): Located in the neck region (C1 to C7). This number is almost constant among mammals.
• Thoracic Vertebrae (12): Located in the chest region (T1 to T12). These articulate with the ribs.
• Lumbar Vertebrae (5): Located in the lower back (L1 to L5). These are the largest and strongest vertebrae to support body weight.
• Sacral Vertebrae (1-fused): In adults, 5 embryonic sacral vertebrae fuse to form a single triangular bone called the Sacrum.
• Coccygeal Vertebrae (1-fused): In adults, 4 embryonic coccygeal vertebrae fuse to form a single vestigial bone called the Coccyx (tailbone).

Thus, the formula is C7, T12, L5, S1, Co1.

Key Takeaway: The adult human vertebral column contains 26 bones derived from 33 vertebrae, with the formula C₇ T₁₂ L₅ S₍₁₎ Co₍₁₎.