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320 bytes added ,  19:43, 4 June 2014
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*Myofibrils removed by disintegration -> sacrolemma too large -> forms folds
 
*Myofibrils removed by disintegration -> sacrolemma too large -> forms folds
 
*Caused by:
 
*Caused by:
**<u>'''Disuse'''</u> (e.g. fracture, failure to use limb, recumbency)
+
**<u>'''Disuse atrophy'''</u> (e.g. fracture, failure to use limb, recumbency)
 
***Slower than denervation atrophy
 
***Slower than denervation atrophy
 
***Reversible unless too prolonger or severe to cause loss of myofibres
 
***Reversible unless too prolonger or severe to cause loss of myofibres
**<u>'''Denervation'''</u>
+
**<u>'''Pressure atrophy'''</u>
 +
***Any prolonged pressure on muscles resulting in muscle atrophy
 +
****Abscesses, neoplasms, parasitic cysts
 +
**<u>'''Denervation atrophy'''</u>
 
***Any interference or damage to its nerve supply results in muscle atrophy
 
***Any interference or damage to its nerve supply results in muscle atrophy
 
****Can be rapid - over 50% of muscle mass may be lost in a few weeks e.g. roarer horses with [[Laryngeal Hemiplegia|laryngeal hemiplegia]]
 
****Can be rapid - over 50% of muscle mass may be lost in a few weeks e.g. roarer horses with [[Laryngeal Hemiplegia|laryngeal hemiplegia]]
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***Sometimes replaced by fat tissue -> increased size of muscle = ''pseudohypertrophy''
 
***Sometimes replaced by fat tissue -> increased size of muscle = ''pseudohypertrophy''
 
***Muscle may have a mixture of atrophied and [[Muscle Hypertrophy|hypertrophied]] (due to increased work load) fibres if some motor units are not damaged
 
***Muscle may have a mixture of atrophied and [[Muscle Hypertrophy|hypertrophied]] (due to increased work load) fibres if some motor units are not damaged
**<u>'''Metabolisation of muscle protein'''</u> for nutrients during:
+
**<u>'''Nutritional atrophy'''</u> for nutrients during:
 
***Malnutrition, cachexia, senility
 
***Malnutrition, cachexia, senility
 
***Gradual onset except for some febrile diseases causing cachexia
 
***Gradual onset except for some febrile diseases causing cachexia
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***Grossly:
 
***Grossly:
 
****Smaller, darker, thinner muscles
 
****Smaller, darker, thinner muscles
 +
***<u>'''Senile atrophy'''</u>
 +
****Similar to  nutritional atrophy.
 +
****Lipofuscin pigmentation is common
 +
*****Grossly:
 +
******Yellow-brown / dark brown colour (esp in diaphragm)
    
[[Category:Muscles - Degenerative Pathology]]
 
[[Category:Muscles - Degenerative Pathology]]

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