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A sequestrum (plural: sequestra) is a piece of dead bone [1] that has become separated during the process of necrosis from normal or sound bone. It is a complication (sequela) of osteomyelitis. The pathological process is as follows: infection in the bone leads to an increase in intramedullary pressure due to inflammatory exudates
Thermal effects (extremely high or low temperature) can often result in necrosis due to the disruption of cells, especially in bone cells. [16] Necrosis can also result from chemical trauma, with alkaline and acidic compounds causing liquefactive and coagulative necrosis, respectively, in affected tissues. The severity of such cases varies ...
Bones are commonly described with the terms head, neck, shaft, body and base. The head of a bone usually refers to the distal end of the bone. The shaft refers to the elongated sections of long bone, and the neck the segment between the head and shaft (or body). The end of the long bone opposite to the head is known as the base.
Avascular necrosis (AVN), also called osteonecrosis or bone infarction, is death of bone tissue due to interruption of the blood supply. [1] Early on, there may be no symptoms. [1] Gradually joint pain may develop, which may limit the person's ability to move. [1] Complications may include collapse of the bone or nearby joint surface. [1]
The osteoclast disassembles and digests the composite of hydrated protein and mineral at a molecular level by secreting acid and a collagenase, a process known as bone resorption. This process also helps regulate the level of blood calcium. Osteoclasts are found on those surfaces of bone that are undergoing resorption.
The N and Q lineages contribute two blast cells for each segment, while the M, O, and P lineages only contribute one cell per segment. [5] Finally, the number of segments within the embryo is defined by the number of divisions and blast cells. [2]
The axial skeleton (80 bones) is formed by the vertebral column (32–34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), a part of the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones).
Mesenchymal (mesoderm origin) stem cells are undifferentiated, meaning they can differentiate into a variety of generative cells commonly known as osteochondrogenic (or osteogenic, chondrogenic, osteoprogenitor, etc.) cells. When referring to bone, or in this case cartilage, the originally undifferentiated mesenchymal stem cells lose their ...