Bone MicroanatomyCredit:

Did you know that the bone is a living structure? It does not only support your body but it also grows as you grow. When you were born, you have more than 300 bones and as you grow and become an adult, the number of bones you have becomes 206. This is because some of the small bones fuse together as you grow and the best example of this is your skull.

The Bones - Bone MicroanatomyCredit:

The Bones

A vascular, living structure made up of organic tissues which make up 35% of the weight of the bone. These organic tissues include cells, vessels, nerves, extracellular matrix and fibers. The other 65% of the weight of the bone is from the minerals within it, which is largely calcium. It is already mainstreamed that the function of the bone is to support our body, but in addition to this function, it also serves as a point in which muscle, tendons and ligaments attaches. It also serves as a storage site for calcium and a key player in hematopoiesis or blood cell development. The femur is the longest bone in your body while the smallest bone is located in the ear, the stapes.

Epiphysis - Bone MicroanatomyCredit:


The articular end of any part of a bone alienated from the main body of an immature bone by a cartilage. The epiphysis is formed from a secondary site of ossification. To explain it simply, as the body grows the end part of the bone become separated from the main body of another bone, but it time it gets connected again by a cartilage through the process of secondary ossification.

Diaphysis - Bone MicroanatomyCredit:


Medical professionals refer to it as the diaphysis; lay people call it the center or body of the bone. Inside the diaphysis is a marrow-filled cavity, called the medullar cavity encapsulated by a hard bone with periosteum lining on the external part and endosteum lining on the internal part. This part of the bone is continuously supplied with nutrients by vessels because it is in the inside of this bone that red blood cells develop.

Articluar Cartilage - Bone MicroanatomyCredit:

Articluar Cartilage

We may picture an adult to have a complete, solid group of bones. The articular cartilage is the only evidence of the cartilaginous past. This part of the bone is bloodless, smooth and slippery. The articular cartilage is of importance to medical professional since this is the part where arthritis strikes. When somebody has arthritis, its degenerative process means the fibrillation and breakdown of this cartilage. A continuous supply of nutrients and oxygen from the subchondral bone permits movement and absorption of synovial fluid.

Periosteum - Bone MicroanatomyCredit:


The life support of the bone, the periosteum provides nutrient-rich blood to the bone cells. It is vascular, cellular, highly sensitive and fibrous. Osteoprogenitor cells or the cells that regenerate and repair fractured bones come from the periosteum.    

Cancellous Spongy Bone - Bone MicroanatomyCredit:

Cancellous/Spongy Bone

Like a real sponge, this bone can withstand pressure forces applied in many directions. It is located in the ends of long bones and at the center of flat and irregular bones. Cancellous bones is composed of trabeculae and the spaces among the trabeculae are filled with red and yellow marrow and blood vessels.

Compact Bone - Bone MicroanatomyCredit:

Compact Bone

The compact bone or dense bone covers the spongy bone. It forms a cylinder around a central marrow cavity and is better able to withstand longitudinal forces than horizontal forces.

Medullary Cavity - Bone MicroanatomyCredit:

Medullary Cavity

The cavity of the diaphysis, an abundance of osteoprogenitor cells can be found in the endosteal tissue, which lines the medullary cavity. It contains the red and yellow bone marrow. For those who are wondering, the red bone marrow are young and the yellow are mature ones.

Red Bone Marrow - Bone MicroanatomyCredit:

Red Bone Marrow

From the name itself, it is red and gelatinous. It is composed of red blood cells and white blood cells in varying forms of development and specialized capillaries in reticular tissue. Interestingly, during birth a person only has red bone marrow.

Yellow Bone Marrow - Bone MicroanatomyCredit:

Yellow Bone Marrow

The yellow bone marrow derives its color from the concentration of fat cells in the cavity. Although some white blood cells can be produced by the yellow bone marrow, it is incapable of creating red blood cells. Once the power to create red blood cells by the red bone marrow is depleted, it gets replaced by the yellow bone marrow.

Nutrient Artery - Bone MicroanatomyCredit:

Nutrient Artery

The lifeline of the bone, the nutrient artery is the primary supplier of nutrients and oxygen-rich blood to the body of the bone or the shaft. Its capillaries reach the inner depths of the bone to deliver the much needed materials for red and white blood cell production.


Many interesting facts exist with regards to our bone. Do you know that the number of bones a giraffe has in its neck is the same number of bones we have in our neck? So much more can be learned by studying the bones and we are taking a step further towards this understanding.