CHAPTER IX 



EFFECTS ON THE MUSCULATURE 



The present chapter deals with the effects of inanition upon the skeletal 

 musculature only. The cardiac muscle will be considered in connection with 

 the heart, and smooth muscle in connection with the various organs in which it 

 occurs. (See Index.) The marked atrophy of the musculature explains the 

 characteristic weakness generally appearing in both total and partial inanition, 

 as well as in various chronic diseases involving malnutrition. Under such 

 conditions the musculature appears to serve as a storehouse of protein, fat and 

 glycogen reserves for the exhausted organism. After a brief summary, the 

 effects of inanition upon the musculature will be dismissed under (A) total 

 inanition and (B) partial inanition. 



Summary of Effects on the Musculature 



During total inanition, there is in adults, both human and animal, a marked 

 loss in the weight of the skeletal musculature, which in general is roughly pro- 

 portional to that of the entire body. The loss in the musculature is relatively 

 greater in some species (frogs), and in general is somewhat greater in chronic 

 (incomplete) than in acute inanition. The degree of atrophy apparently varies 

 in different regions of the body. 



In young animals (rats) held at constant body weight by underfeeding, the 

 musculature tends to increase slightly in weight. In malnourished human 

 infants, the musculature appears atrophic, but it is questionable whether there 

 is much actual loss of weight except in extreme cases. The appearance of ema- 

 ciation may be increased by the relative growth of the skeleton. Recovery in 

 the musculature after inanition usually appears promptly upon adequate 

 refeeding. 



The histological changes in the skeletal muscle fibers involve first a simple 

 atrophy — a decrease in size with no evident changes in structure. The ordinary 

 (neutral) fat, both interfibrous and intrafibrous, undergoes progressive resorp- 

 tion, but the phosphorized lipoidal granules are very resistant to inanition. 

 Later certain of the muscle fibers begin to show degenerative changes, with 

 progressive loss of the characteristic striations in the myofibrillae, granular 

 (fatty, albuminous or pigmentary) degeneration in the sarcoplasm. Waxy 

 degeneration is rare. The nuclei are more resistant, and often undergo prolifera- 

 tion. A variable degree of hyperplasia (fibrosis) occurs in the interstitial 

 connective tissue. The extent of the degeneration varies greatly, not only in 

 different fibers of the same muscle, but also in the muscles in different regions of 

 the body. 



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