What is the difference between compact bone and spongy bone?
Answer (1)
Compact bone and spongy bone are two types of osseous tissue that form the human skeleton, each with distinct structure and function.Compact bone (also called cortical bone) is the dense, hard outer layer of bone. It makes up approximately 80% of the total bone mass in the adult human body. Its primary function is to provide strength and protection. It consists of tightly packed osteons or Haversian systems—cylinder-shaped units that contain blood vessels and nerves running through a central canal. These structures help resist bending and compression, which is why compact bone is mostly found in the shafts of long bones like the femur and humerus.Spongy bone (also called cancellous or trabecular bone) is the lighter, porous inner part of the bone. It contains a network of trabeculae—thin bony plates arranged in a honeycomb-like structure. The spaces between trabeculae are filled with bone marrow, where blood cell formation occurs (hematopoiesis). This type of bone is found in the ends of long bones, inside vertebrae, ribs, skull, and pelvis. While it is not as dense as a compact bone, it is structurally strong and helps absorb shock.In short:Compact bone: Dense, solid, external; supports and protects.Spongy bone: Porous, internal, lightweight; contains marrow and absorbs impact.Together, they give bones their strength, flexibility, and lightness—allowing movement without making the body too heavy.
