Cancellous bone primarily serves to:

• A. Absorb external mechanical stress
• B. Store mineral salts exclusively
• C. Form the outer protective layer
• D. Produce marrow

Answer: (A)

Cancellous bone is a porous, lattice-like network (trabecular bone) that is organized to distribute and absorb forces within the bone. The trabeculae align along lines of stress, so when a load is applied, the structure spreads forces through the network, reducing concentrated stress and helping to cushion impacts. This makes cancellous bone effective at absorbing external mechanical stress, especially in areas like the ends of long bones and the vertebrae where forces are multidirectional.

In contrast, the outer protective shell of bone is dense cortex (cortical bone), which provides rigidity rather than shock absorption. Cancellous bone also houses marrow within its spaces, supporting hematopoietic activity, but it does not produce marrow. Mineral storage occurs throughout bone tissue, not exclusively in cancellous bone.