Periosteum Structure and Role in Bone Growth

The Periosteum meaning and role can be drawn to similarities to that of skin. Just like the skin covers the outer surface of the body, the periosteum is a thick layer that is the outer covering of bone. The Periosteum of bone covers the outer surfaces but not the joint spaces which are called articular surfaces which are lined by synovial membrane. Bones are very crucial as it protects our bodies, organs and even carries our entire weight. And the periosteal layer of the periosteum of bone protects this important part of our body. Now that we are aware of the periosteum meaning let us understand the anatomy and functions of the periosteum of bone.  

Anatomy of the Periosteum

The periosteum meaning clearly justifies the membranous tissue that is the periosteum covers the bone surface and does not cover the articular surfaces as there are ligaments and tendons attached to this and the areas the cartilage surrounds the bones. The periosteum of bone is made up of two layers of which one is a fibrous membrane made up of connective tissue and the other has osteoblast cells. Let us understand further about these two layers.

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The outer fibrous layer of the periosteum is the fibrous layer which is further divided into two parts. The outer or superficial layer of this fibrous membrane has very few elastic fibres and is predominantly made up of a collagenous matrix with interspersed elongated fibroblasts. This layer also has blood vessels which can be referred to as the periosteal vessels and the nerves and are the most highly vascularized substratum hence the primary contributor to the blood supply to the skeletal muscle and even the bones. The deeper layer of the outer layer is more elastic because of many fibroelastic cells and is not very vascularised.

The inner layer of the periosteum is the highly cellular cambium layer can. It contains osteoblast cells and mesenchymal progenitor cells. Due to its cellular nature, it is responsible for appositional growth. In the fetus stage, it has a lot of significance and even in the early years due to its osteoblastic potential and it decreases with age, most of it reduced during childhood itself. In adults, the fibroblasts in the inner layer are elongated with a configuration essentially indistinguishable from the fibroblasts adjacent to it that lie in the outer layer. 

Periosteum and Endosteum

The two layers that protect the bones are the periosteum which is the outer layer and the endosteum the inner layer in bone and often they are used interchangeably because of their similarities like both are made up of connective tissue, both contain fibroblasts, osteoblasts, and osteoprogenitor cells and even play a key role in bone remodelling but they have a lot many differences.

Differences Between Periosteum and Endosteum

Periosteum Functions

• The periosteal vessels of the periosteum in the outer layer enter perpendicularly through  Volkmann canals and enter another group of canals that run along the bones called Haversian canals, and thus are highly sensitive to any function occurring in the bones.

• The periosteal vessels easily identify if any tissue is injured or damaged. It is because of these vessels one is able to register the pain. 

• When the nerves then send a signal of the pain to the brain the healing stage and process begins.

• The osteoblasts cells in the cambium layer play an important role in bone formation.

• The periosteum without covering the tendons and ligaments joining the bones provides attachment sites.

• This layer even provides nourishment to the compact bones. 

• Provides a medium through which muscles are also attached to the bones.

• The periosteum is also called the limiting layer as the outer fibrous layer prevents the bone tissue from spilling out into neighbouring tissues that are into the ridges and tubercles and even the waste removal process is also carried within the periosteum layer boundaries. 

Damage of Periosteum

Often the periosteum damage of the bones is due to inflammation and the condition is called periostitis. And the damage can also be due to an infection. People who experience this kind of condition are often athletes. It can be acute periostitis or chronic periostitis.

Ways to Avoid Periostitis

• The recovery period depends on the severity of the injury and it usually lasts 2-4 weeks to 6-8 weeks one must be regular with medication and in case of chronic condition keep applying ice packs.

• The acute condition can be managed once you reduce the risk factors that cause the diseases leading to acute periostitis.

• If you are diabetic manage your blood sugar level and if advised also take the insulin from an external source.

•  Stay healthy by exercising but avoid high impact exercises.

• Stay active and manage your weight.

• Reduce cholesterol levels by avoiding oily and unhealthy foods.

• Blood pressure also needs to be maintained by reducing the intake of salty foods

• Dietary changes can do wonders for the body

• Alcohol and smoking only worsen the condition of the pain and infection so avoid at all costs.

Conclusion

Even though the periosteum does not contribute to bone growth in adults it does a great job in supplying blood and nourishment and the inner layer protects it from injuries and damage and even aids in the healing processes of fractures of any sort. And one must be careful as any damage to the periosteum be it through overuse or infection the consequences only makes the bones more prone to fractures. And as one ages fracture healing is more painful and if one has an infected and damaged periosteum the healing is not up to mark. Hence periosteum must be very well protected and taken care of because it provides a cushion for the bones that carry our body.