Cancellous bone is spongy bone.

• A. Dense outer bone
• B. Bone marrow
• C. Spongy bone
• D. Cartilage

Answer: (C)

Cancellous bone is the spongy, porous interior of bone formed by a lattice of trabeculae. This network creates many small spaces that are often filled with red marrow, making the bone lighter yet still strong and providing a large surface area for metabolic activities like hematopoiesis. The outer shell of a bone is dense, compact bone, not cancellous. Bone marrow sits in the spaces of cancellous bone but isn’t the cancellous tissue itself. Cartilage is a different tissue that covers joints and ends of bones, not cancellous bone. So the term cancellous bone correctly describes spongy bone.