What are the differences between compact bone and spongy bone?


Quick Answer

The main difference between compact and spongy bone is that compact bone is the firmer outer layer of bone tissue and spongy bone is the softer, more porous inner bone tissue. There are several other differences between these two types bone tissue. These tissues are also known as osseous tissue.

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Full Answer

Compact bone is the outer layer of bone and forms the shaft of long bones as well. It is also known as cortical bone. This bone tissue's primary purpose is to support the body. Compact bone is composed of many rod-shaped units called known as either osteons or Haversian systems. This type of bone tissue stores calcium, which gives the bone tissue its hardness.

Spongy bone is the porous inner bone tissue that lies underneath compact bone. This inner bone tissue is also known as cancellous bone. Spongy bone is composed of a network of thread-like thin bones called trabeculae. The arrangement of the trabeculae is affected by stress or trauma to the bone.

The porosity of spongy bone allows it to develop and harbor bone marrow. This is also the more vulnerable bone tissue and the area that is affected by diseases such as osteoporosis. If spongy bone does not receive and adequate supply of calcium it weakens and breaks more easily.

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