422 



THE TISSUES. 



Fig. 271. 



may also be distinguished, as somewhat clearer but still transparent 



streaks. 



In the fourth month, both the muscular, tissue and the tendons 



are more distinct, the former being, on the trunk, of a light reddish 



color. At birth, the muscular fibres are still softer and paler, and 



the tendons more vascular and less white than they subsequently 



become. 



The elementary parts of the tendons are never formed earlier 



than those of the muscular portion. Indeed, they cannot be recog- 

 nized as fasciculi of the white fibrous tissue till 

 about the fourth month, though the muscular 

 fibres are quite distinct at the eighth to the ninth 

 week. Being j^^nr to T?-W of an inch in diame- 

 ter at the fourth month, the fasciculi (at first con- 

 taining no distinct fibres) become g^Viy to J-SQ-Q of 

 an inch in diameter at birth. At this time, also, 

 their fibres are distinct, and the fine elastic fibres 

 are developed between the fasciculi from special 

 fusiform formative cells. Fig. 271 shows the wavy 

 appearance of the fasciculi at birth, and also the 

 elongated nuclei lying upon and among them, 

 from which the elastic fibres are probably deve- 

 loped. (See also Figs. 261-2.) 



In the adult, the fasciculi of the tendons are 



t f j r>f an innli ir> rliamptAr TTiPir T-A!O 



* TW Ol an mCn m diameter. 



From the tendo-Achillia 

 of a new-born child, mag- 3 



nifled 250 diameters ; and tive size, therefore, in the foetus at four months, 

 ;r"l a ^; the new-born child, and the adult, are as 1 : 1.8 : 6; 

 of the fine elastic fibres, go that the growth of the tendons, after birth at 

 least, seems due to the increased thickness and 

 elongation of their fasciculi ; while their number also is constantly 

 increased during foetal life. 



Pathological States of the Muscles and their Accessories. 



The pathological states of the striated muscular tissue have already 

 been specified (p. 406) ; of which hypertrophy, atrophy, paralysis, 

 fatty degeneration, and softening are the most important. 



The most common pathological state of the tendons and aponeu- 

 roses is atrophy, consequent on the same condition of the mus- 

 cular fibres, and disease of the muscle. The tendons also become 

 shortened in case of talipes (club-foot) and other deformities ; since 

 changes in the relations of the bones have brought the points of in- 



