3 Things You Don’t Know About Cortical Bone

Benign Fibrous Histiocytoma of a Long Bone in a 65 year-old Female Patient
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The human body is amazing. How we are put together and function like a well-oiled machine is nothing short of miraculous. We consist of both hard parts and soft parts, and the soft parts are often protected by a rigid system we call the skeleton, of which, cortical bone plays an important role.

The ability of the different systems in our bodies to work together gives us the opportunity to live the best life possible. It doesn’t always go smoothly, however, and occasionally we get sick or injured, but there are ways to take care of that. Keeping your body healthy and your bones strong will ensure a long, happy life.

What Is Cortical Bone?

There are two types of bones in the human body: cortical bone and cancellous bone. Cancellous bone, also referred to as spongy bone, is found deep within our skeletons and functions as internal support.

Cortical bone, also referred to as compact bone, is a dense, strong bone that forms the rigid outer layer on all bones. It is not solid, however, and has tiny passages so that nerves and blood vessels can travel through. It also contains cells that maintain and repair the bones.

What Is Cortical Bone Made Of?

Cortical bone consists of osseous tissue, which is a connective tissue that is specific to bone. This tissue contains osteocytes that are covered in an intercellular mixture of protein fibers and salts. This tissue is also rich in calcium and the mineral hydroxyapatite, which contains phosphorus. Hydroxyapatite is hard and rigid, so it has to be mixed with collagen protein fibers to give it some flexibility and resistance to stress.

How Does Cortical Bone Form?

Microscopic cylinders, which are called osteons, surround teeny central canals to make up the structure of cortical bones. During fetal development, the osteon forms when blood vessels and nerve fibers travel through a mesenchymal tissue that contains osteogenic cells, which then form a bone matrix ring, called the lamella, around the blood vessels and nerves.

After the lamella forms, the osteogenic cells turn into osteocytes and get trapped in the osseous tissue in cavities that are called lacunae. The osteogenic cells that are a distance away from the central canal form more lamella around the layer that developed before it and develop into another group of osteocytes that get stuck in the lacunae.

The lacuna and osteocytes that form stay in contact and receive oxygen and nutrients from blood vessels that travel through canals called canaliculi. The process of lamellae forming around the central canal repeats several times and results in concentric layers. Eventually, the cells can’t support any more layers, so the process ends. More blood vessels will develop near existing osteon and create new osteon, which then fuse together and create a continuous layer of cortical bone.

What Is The Role Of Compact Bone?

This bone is the densest and hardest tissue in our bodies. It supports and protects soft tissues and gives us our shape. As we apply stress to our bodies through weight-bearing activities, it changes how thick the cortical bone is. The stress activates osteoblasts, which then produce a mineral matrix that forms new layers of compact bone.

If the stress on the bone decreases, osteoclast cells tear down the mineral matrix, reducing the bone’s mass and releasing the mineral ions into the bloodstream. In essence, the osteoblasts and osteoclasts are responsible for monitoring and controlling the mass of the cortical bones and their strength.

Your level of activity determines when these processes take place by the amount of stress you put on your bones. These cells also control mineral homeostasis by either storing extra minerals in the compact bone or sending them into the blood when your body doesn’t have enough minerals.

How Disease Affects The Cortical Bone

There are a variety of different diseases that can impact our bones. The most common affliction is osteoporosis. There are several different classifications of the disease, and it can be caused by numerous factors, including nutrition, genetics, or medication.

Other bone diseases include rickets, renal osteodystrophy, Paget’s disease, osteogenesis imperfecta, and cancers or tumors that develop in the bone.

Osteoporosis

This bone disease occurs when your body doesn’t make enough bone, loses bone, or both. The result is that bones become weak and brittle, breaking easily during a fall. Bones that are impacted by osteoporosis are less dense, have less mass, and contain abnormal tissue structures.

Osteoporosis affects more than 50 million Americans. It is more commonly found in women, but men can also be affected by the disease. It generally hits individuals who are 50 years of age and older.

The Causes Of Bone Loss

man eating food
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There are a variety of different health problems and ailments that may contribute to the development of osteoporosis. These include autoimmune disorders (for example, lupus or rheumatoid arthritis), gastrointestinal and digestive issues (such as celiac disease and inflammatory bowel disease), cancer, blood disorders (including sickle cell disease or leukemia), neurological or nervous systems disorders (including Parkinson’s disease, stroke, or MS), or bone marrow disorders, among several other issues.

Eating disorders and medications may also contribute to bone loss that can develop into osteoporosis. The medications include chemotherapeutic drugs used in the treatment of cancer, methotrexate, lithium, aluminum-containing antacids, steroids, or excessive thyroid hormones, in addition to many others.

Other Bone Diseases

Rickets is most commonly found in children and is the result of vitamin D deficiency. The bones get weak and soft. This disease can lead to delayed growth; muscles weakness; pain in the pelvis, spine, and legs; knocked knees or bowed legs; and the projection of the breastbone.

Renal osteodystrophy occurs when a person’s kidneys fail to produce enough or maintain adequate levels of phosphorus and calcium in the blood. It occurs most often in children, but adults can show signs of this disease after being on dialysis for years.

Bone cancers and tumors can develop in any bone at any time. They often contribute to bone pain, fatigue, unintended weight loss, tenderness and swelling of the affected area or around the area, and bones that are weakened and can be easily broke.

Impacts Of Disease On Cortical Bone

The impact of any disease on cortical bone is to break down its sturdy structure and make it susceptible to breakage. This can lead to debilitation in the affected person and make it hard for them to live their daily life. Depending on the severity and type of disease, the effects may be irreversible and permanent.

illustration of osteoporosis in human bone
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3 Things You Don’t Know about Cortical Bone

Your bones are the strongest part of your body, and they keep you upright and protect your soft tissues. They give you shape. They are an amazing structure, and there are some interesting things about cortical bone that you might not have known. Here are three.

1. You Have The Ability To Improve Cortical Bone Strength

The food you eat and the exercises you participate in have an impact on the strength of your bones. The more weight-bearing exercises you do, the more your bones react. The (good) stress these activities put on your bones encourages them to develop more layers, making them stronger so you can be stronger.

The types of foods you eat can also make your bones strong. Eating foods that are rich in calcium gives bones the nutrients they need. These include certain types of fish, dairy products, and broccoli.

Over time, your bones will lose strength, but feeding them with the proper foods and exercising will slow that loss down.

2. Artificial Bones Are Being Developed For Faster Bone Regeneration

Cortical bones do an amazing job of repairing themselves. They have a process in place that allows bones to be rejoined after they are broken. Sometimes, though, bone can be lost or damaged and unable to repair itself. When that happens, the person may become disabled.

However, with advancements in science, there has been research into creating artificial bones. Originally, artificial bones were developed as prosthetics and were often made out of metals and ceramics. These often made it difficult for patients to be able to move because these materials are so rigid.

In an attempt to create something better and more closely resembling the true structure of bones in the human body, scientists in Japan were able to mix biomaterial collagen and hydroxyapatite to create a flexible, fibrous material. Initial tests and studies have proved promising, and bone regeneration capabilities have advanced.

3. Cortical Bones Make Up Most Of The Human Skeleton

About 80% of the human skeleton is made up of cortical bones. It is most commonly found in the shaft of long bones, such as those in your legs.

Conclusion

illustration of a girl's body anatomy
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Without a skeletal system, humans wouldn’t be able to stand upright. We would be nothing but a pile of flesh and internal organs that slithered across the floor. Cortical bones are an incredibly important part of our bodies, and they are resilient, able to repair quickly after damage, and are found throughout our bodies.

Disease, age, and medications can take its toll on our bodies and bones, but by eating right and exercising, we can do our bodies good and keep our bones healthy and strong.