In the adult skeleton, how many bones belong to the axial skeleton?

• A. 80
• B. 126
• C. 206
• D. 100

Answer: (A)

The key idea is which bones are considered part of the central axis of the body. The axial skeleton includes the skull, the hyoid bone in the neck, the vertebral column, and the rib cage. In adults, these bones add up to 80: the skull has 28 bones (8 cranial, 14 facial, plus the 6 auditory ossicles counted with the skull); the hyoid adds 1; the vertebral column has 26 vertebrae (7 cervical, 12 thoracic, 5 lumbar, plus the sacrum and coccyx counted as single bones each); and the thoracic cage has 25 bones (24 ribs and the sternum). Summing to 28 + 1 + 26 + 25 = 80. The remaining bones form the appendicular skeleton (126), and together they total 206 bones in the adult.