440 



DISTRIBUTION OF VESSELS AND NERVES. 



Muscular arteries and veins. 



They never penetrate 



is shown in Fig. 227, a being .the artery, b the ^ 227. 



. vein, c, capillary plexus. Each ar- 



Distribution of ' ' r J r 



blood-vessels to tenal branch has usually two vena3 

 muscle. comites, and the supply of these 



capillaries has a general correspondence to the 

 number of fibrils. The lymphatics are not nu- 

 merous. Vascular distribution to the tendons 

 is much more sparing. By the muscular blood- 

 vessels a triple function has to be discharged: 

 they furnish oxidized blood, on which the action 

 of the muscle depends ; they remove the waste 

 which arises as the consequence of that activity ; 

 they also repair that waste by presenting the 

 elements of nutrition. The younger Liebig has 

 demonstrated that a muscle can not contract ex- 

 cept it be furnished with oxygen, and that, as 

 long as the capacity for contraction continues, it 

 absorbs oxygen and yields carbonic acid. 



In the same general manner that the blood- 

 vessels are distributed, so likewise are the 

 nerves. An example of this is seen in Fig. 228. 

 , the sarcolemma, 



Distribution of 



nerves to mus- but run ill close 



contiguity with 

 it, their distribution to dif- 

 ferent parts of the fasciculi 

 being very unequal, some 

 parts being quite scantily fur- 

 nished, the nerve filaments 

 coming in contact, as it were, 

 at occasional points. The 

 opinion is generally maintain- 

 ed among physiologists that 

 the nerves present toward 

 their extremities a looped arrangement, as shown in Fig. 228, but by 

 some it is asserted that the termination is in an extremely delicate point, 

 or bifid, or trifid, without exhibiting any return. Of the two forms of 

 muscular tissue, the striated is, for the most part, supplied from the cere- 

 bro-spinal system, the non-striated from the sympathetic. 



The manner of development of muscular fasciculus seems to be, that 

 Development the sarcolemma is first produced as a thin and delicate tube 

 of muscle. ^ fa Q coa lescence of cells arranged linearly, the walls of which, 

 where they come in contact at the ends, are obliterated, giving origin to 



Distribution of muscular nerves. 



