compact bone
(noun)
One of the two types of osseous tissue that form bones.
Examples of compact bone in the following topics:
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Gross Anatomy
- All the bones in the body can be described as long bones or flat bones.
- Cortical bone is compact bone, while cancellous bone is trabecular and spongy bone.
- The outer shell of the long bone is compact bone, below which lies a deeper layer of cancellous bone (spongy bone), as shown in the following figure.
- They are composed of two thin layers of compact bone surrounding a layer of cancellous (spongy) bone.
- The hard outer layer of bones is composed of compact bone tissue, so-called due to its minimal gaps and spaces.
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Microscopic Anatomy of Bone
- The basic microscopic unit of bone is an osteon, which can be arranged into woven bone or lamellar bone.
- Each osteon consists of a lamellae of compact bone tissue that surround a central canal (Haversian canal).
- Osteons can be arranged into woven bone or lamellar bone.
- Lamellar bone makes up the compact or cortical bone in the skeleton, such as the long bones of the legs and arms.
- A photo taken through a microscope that shows the anatomy of compact bone with a detailed view of an osteon.
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Bone Repair
- The next phase is the replacement of the hyaline cartilage and woven bone with lamellar bone.
- Substitution of the woven bone with lamellar bone precedes the substitution of the hyaline cartilage with lamellar bone.
- This new lamellar bone is in the form of trabecular bone.
- The remodeling process continues with substitution of the trabecular bone with compact bone.
- The trabecular bone is first resorbed by osteoclasts, creating a shallow resorption pit known as Howship's lacuna, and then osteoblasts deposit compact bone within the resorption pit.
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Embryonic and Fetal Bone Formation
- Eventually, woven bone is replaced by lamellar bone.
- The primary center of ossification is the area where bone growth occurs between the periosteum and the bone.
- Osteons are units or principal structures of compact bone.
- When replacement with compact bone occurs, this blood vessel becomes the central canal of the osteon.
- It is also an essential process during the rudimentary formation of long bones, the growth of the length of long bones, and the natural healing of bone fractures.
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Thoracic Cage: Sternum
- The sternum or breastbone is a long, flat, bony plate connected to the rib bones via cartilage that forms the anterior section of the rib cage.
- The sternum is highly vascular in nature and covered with a thin layer of compact bone providing a degree of flexibility.
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Capacity of Different Tissues for Repair
- The next phase is the replacement of the hyaline cartilage and woven bone with lamellar bone.
- Substitution of the woven bone with lamellar bone precedes the substitution of the hyaline cartilage with lamellar bone.
- This new lamellar bone is in the form of trabecular bone.
- The remodeling process substitutes the trabecular bone with compact bone.
- The trabecular bone is first resorbed by osteoclasts, creating a shallow resorption pit known as a "Howship's lacuna. " Then osteoblasts deposit compact bone within the resorption pit.
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Supply of Blood and Nerves to Bone
- The blood and nerve supply to bones are carried in Haversian canals that run along the long axis of bones.
- Blood is supplied to mature compact bone through the Haversian canal.
- The Haversian canals also surround nerve cells throughout the bone and communicate with osteocytes in lacunae (spaces within the dense bone matrix that contain the living bone cells) through canaliculi.
- The vascular supply of long bones depends on several points of inflow, which feed complex sinusoidal networks within the bone.
- The Haversian canals surround blood vessels and nerve cells throughout the bone.
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Types of Connective Tissue
- Bone tissue is also called the osseous tissue.
- It is mostly formed of calcium phosphate in the chemical arrangement termed calcium hydroxyapatite, which gives bones their rigidity.
- The hard outer layer of bones is composed of compact bone tissue, so-called due to its minimal gaps and spaces.
- This tissue gives bones their smooth, white, and solid appearance, and accounts for 80% of the total bone mass of an adult skeleton.
- Filling the interior of the bone is the trabecular bone tissue (an open cell porous network also called cancellous or spongy bone), which is composed of a network of rod and plate-like elements that make the overall organ lighter and allow room for blood vessels and marrow.
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Comparison of Female and Male Pelves
- The female pelvis is larger and broader than the male pelvis, which is taller (owing to a higher iliac crest), narrower, and more compact.
- The distance between the ischium bones is small in males.
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Bone Grafting
- Bone grafting is a surgical procedure that replaces missing bone in order to repair bone fractures.
- Bone grafting is a surgical procedure that replaces missing bone in order to repair bone fractures that are extremely complex, pose a significant health risk to the patient, or fail to heal properly .
- Bone grafts may be autologous (bone harvested from the patient's own body, often from the iliac crest), allograft (cadaveric bone usually obtained from a bone bank), or synthetic (often made of hydroxyapatite or other naturally-occurring and biocompatible substances) with similar mechanical properties to bone.
- Most bone grafts are expected to be reabsorbed and replaced as the natural bone heals over a few months' time.
- Bone grafting is also used to fuse joints to prevent movement, repair broken bones that have bone loss, and repair broken bone that has not yet healed.