Difference Between

Compact Bone vs Spongy Bone | Cortical vs Spongy Bone

Bones are hard organs inside our bodies that make up our skeletal system. They serve the purpose of protecting our bodies and provide a structure and shape to our bodies. Bones are important as they produce red and white blood cells and also provide place for storing minerals. There are 206 bones in an adult and they come in many shapes and sizes, the longest of them all is Femur. Many people are confused about differences between compact and spongy bone but the fact is that these are not different types of bones but instead parts in a bone having different characteristics. This article will help in understanding these differences.

To begin with, contrary to common misconception, a bone is not a uniformly solid structure. It has soft parts inside that are holes or spaces in between hard parts. Nearly all bones have a compact bone tissue that is what gives the bone a white, smooth and solid appearance. Compact bone tissue has very few gaps and spaces (thus has very little porosity). A large portion of a bone is comprised of this compact bone tissue (nearly 80%). It is also called dense bone because of its low porosity.

It is in the interior side of the bone that we find spongy or cancellous tissues. This is almost porous network of structures having shapes of rods and plates. Spongy tissues make up only 20% of mass in a bone but their surface area is ten times than that of compact bone tissues. Another difference between compact and spongy bone tissues is that while blood surrounds spongy bone tissues, it is marrow that surrounds bone in case of compact bone tissues. It is in the compact bone tissues that bone marrow is found, which is a yellow colored fluid.