As a thin layer of cells, the periosteum encloses the entire bone up to the boundaries of the joint surfaces covered with cartilage.
The periosteum can be divided into two layers, the tasks of which are to anchor the tendon on the bone surface, as well as nourishing the bones and healing fractures.
Periosteum injuries and inflammations can lead to pain in the context of bone fractures or overloading, since the periosteum, unlike the bone, is very innervated and therefore sensitive.
What is the periosteum?
The periosteum is called the periosteum in technical terms.
It consists of a thin layer of cells that surrounds every bone in the human body. The entire bone with the exception of the joint surfaces, which are covered by cartilage, is included. The periosteum also includes the parts of the tendons and ligaments that are close to the bone.
In contrast to the cell layer on the outer surface, the cell layer on the inner surface of the bone is called the endost.
The tissue is well supplied with blood and is therefore rich in oxygen and nutrients. This is used by the bones for regeneration and nutrition.
The anatomy of the periosteum
The periosteum consists of two layers of cells with several layers of cells per layer. The outer layer is always closer to the skin than the inner layer at any point on the bone. The outer layer of cells is also called the stratum fibrosum in technical terms. The inner layer is sometimes called the osteogenic stratum.
As the name of the stratum fibrosum suggests, the outer layer of cells has a high proportion of fibers. These fibers pull through the layer.
More precisely, this means that the stratum fibrosum has a large number of collagen fibers, which give this cell layer a high level of stability.
The collagen fibers are still called Sharpey fibers, which are also found on teeth.
In addition to the outer layer of cells, the Sharpey fibers also penetrate the inner osteogenic stratum and flow into the bone substance.
The tissue or the cells that form the aforementioned collagen fibers are assigned to the connective tissue.
Furthermore, the fluid surrounding the cells is formed by this connective tissue.
In contrast to the outer layer, the inner osteogenic stratum is rich in cells and even contains stem cells.
These stem cells play an important role in the continuous remodeling of the bone or the regeneration of the bone, for example in the context of a fracture.
In addition to these cells, there are also nerves and blood vessels in the inner cell layer. These are essential for the nutrition and regeneration of the bone.
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What is the function of the periosteum?
The function of the outer cell layer, the stratum fibrosum, is closely related to the location and course of the collagen fibers or Sharpey fibers.
These fibers have a high tensile strength and also have a certain elasticity.
Since the Sharpey fibers reach through the inner cell layer and flow into the hard substance of the bone, they represent an anchor.
This means that the entire periosteum is fixed on the outer surface of the bone through the stratum fibrosum.
The function of the inner cell layer, the osteogenic stratum, is more diverse.
On the one hand, the occurrence of stem cells, which, in contrast to the majority of cells in the body, can still specialize in several types of tissue, can significantly influence fracture healing.
The nerves of the inner cell layer serve to transmit information to the central nervous system.
Among other things, pain stimuli are processed.
The blood vessels of the osteogenic stratum primarily serve to nourish the periosteum and bone. However, like stem cells, they can also play an important role in fracture healing by providing nutrients and cells for it.
Also read our topic: Broken bone
Healing of fractures through the periosteum
If the bone breaks, the inner cell layer of the periosteum plays a major role.
On the one hand, the stem cells of the osteogenic stratum are of essential importance. If a bone fracture occurs, these stem cells divide into two daughter cells. One of these cells retains the function of the stem cells and is still able to divide and transform itself into different types of tissue.The other cell is called osteoblast after division.
After division, the osteoblast is able to form a predecessor of the bone substance, the osteoid, and thus close the fracture gap. In the following, the cell completely integrates itself with the osteoid.
This cell is then called an osteocyte. The osteocyte converts this substance into finished bone substance.
On the other hand, the nutrients that reach the bone and periosteum through the blood vessels are of great importance for the healing of a fracture.
Due to the close proximity of the inner cell layer to the bone, the nutrients can easily reach the cells that make up the bone substance. By diffusion, the nutrients bridge the last stretch from the blood vessels to the osteoblasts.
You can find more information on how to treat a broken bone homeopathically at: Homeopathy for broken bones
What diseases of the periosteum are there?
Periosteum inflammation and its causes
Periostitis is also called inflammation of the leg skin or periostitis.
Since the periosteum is interspersed with numerous nerve fibers, inflammation often leads to severe pain.
This occurs particularly often in the area of the shin. In addition, there is severe swelling due to the increased fluid content. As a rule, however, this is not visible on the surface of the skin.
The diagnosis is made clinically and based on physical examination. If in doubt, an X-ray is taken.
In general, two causes can be named as the cause of periosteum inflammation.
A bacterial infection, for example with staphylococci, is a possible cause.
After a bone marrow inflammation caused by bacteria, the infection often spreads from the bone marrow to the periosteum. A weakened immune system, for example in the context of immunosuppressive therapy, has a beneficial effect.
This is usually treated with antibiotics.
The second possible cause is periosteum inflammation in the context of mechanical overload.
The areas where a muscle, ligament or tendon attach to the bone are mostly affected.
The therapy in this form consists in immobilizing the affected area of the body.
The area can also be cooled and anti-inflammatory medication taken if necessary.
Read more on the subject at: Periosteum inflammation on the shin
The periosteum irritation
Periosteum irritation can theoretically occur anywhere in the body.
However, this very painful irritation occurs particularly frequently in athletes in the area of the shin or forearm.
The cause of periosteum irritation is continuous overload, such as from daily training. The problem can also be caused by an incorrect load, for example due to a faulty running style during sport.
A change in a sequence of movements can also lead to irritation, as the body is not yet used to the new movement.
Periosteum irritation becomes noticeable through severe pain. Most of the time, these only occur during exercise.
Pain at rest or pressure pain is less common. Due to the severe pain, the affected person is often severely restricted in sports or even simple physical work.
Therapy consists in immobilizing the affected area of the body. The area can be cooled to relieve the pain. In addition, short-term medication for the pain can be taken. However, this should not be done regularly.
Furthermore, targeted training control should be considered. With tapes and insoles, the stress during sport can also be alleviated or better distributed over the body.
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Since the periosteum is heavily infused with nerves, an injury usually leads to severe pain. Periosteum injuries usually occur in connection with damage to the bone or the muscles and their tendons.
Since the periosteum is firmly attached to the bone, a fracture is a frequent cause of injury to the periosteum. Furthermore, the periosteum can be damaged by direct force such as a blow. The bone can also be damaged in the process.
In addition, the periosteum can be partially damaged by inflammation or periosteum irritation.
The diagnosis can be made based on clinical appearance and physical examination. If in doubt, an X-ray is taken.
Therapy depends on the cause and may include immobilization or antibiosis, for example.
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What does periosteum pain indicate?
The osteogenic stratum of the periosteum has a high proportion of nerves. Since the bone itself does not have any nerve fibers, the periosteum indirectly takes on an important function in the bone's perception of pain.
Pain that is transmitted through the nerve fibers of the periosteum can have simple reasons but also indicate a serious illness. For example, excessive exercise leads to pain.
Furthermore, the so-called growth pain is not perceived by the bones, but by the nerves of the periosteum.
Some forms of blood cancer called leukemia can also cause pain through the periosteum.
This article might interest you: Symptoms of leukemia
Bruising of the periosteum
A bruise of the periosteum usually occurs as a result of direct violence in the area of the bone.
Areas such as the shin, where the bone lies very superficially under the skin, are particularly at risk. Often this occurs while exercising.
However, it can also be caused by falls or other causes such as an accident. Since the periosteum is very well supplied by nerves, a bruise of the periosteum is usually painful.
In most cases, when the periosteum is bruised, the tissue overlying it is also affected and shows typical signs of a bruise. Edema forms in this tissue and the periosteum and possibly bleeding from the blood vessels.
Read more on the subject at: Bruised bone
When does bleeding under the periosteum occur?
Bleeding under the periosteum usually occurs as a result of direct violence on the body from the blood vessels of the stratum osteogenicum.
This is usually accompanied by a bruise of the periosteum. Hemorrhage is therefore also most frequently localized in those parts of the body where the bone lies very superficially under the skin.
Since the bleeding often leads to a mass beneath the periosteum, this is very painful due to the subsequent stretching. The regression of the hemorrhage can take several months and cause pain even after weeks.
In case of doubt, the diagnosis can be ruled out by taking an X-ray.
What is periosteum cancer?
Periosteum cancer occurs when the cells that make up the bone substance degenerate and is called osteosarcoma.
These original cells are called osteoblasts and are found in the area of the periosteum, among other things.
However, the same type of cancer can also develop within the bone.
The type of cancer is characterized by a high growth rate, which can lead to pain due to overstretching, especially in the periosteum. Depending on the location, size and various other factors, surgical therapy in combination with chemotherapy can achieve a high success rate.
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