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Why can fat and connective tissue replace muscle after nerve injury?

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atrophy One example of atrophy is the progressive loss of bone that occurs in osteoporosis (normal bone shown on left; osteoporotic bone shown on right).

When a muscle loses its motor nerve supply, it enters a state of extreme inactivity, leading to muscular atrophy. While the exact mechanisms are not fully understood, this process involves a significant reduction in blood supply and diminished nutrition to the inactive tissue.1

Within a few weeks of nerve injury, muscle fibers begin to shrink. After several months, these fibers undergo fragmentation and eventually disappear. As the muscle tissue degrades, it is progressively replaced by fat cells and a loose network of connective tissue. This replacement is a characteristic outcome of denervation, where the loss of neural stimulation prevents the maintenance of healthy muscle structure, ultimately resulting in permanent tissue changes and potential contracture.1