NERVES OF THE MUSCLES. 



415 



inclosing the fasciculi, and passing among the individual fibres. 

 (Fig. 268.) Whether there are also free, terminations of the nerve- 

 fibres in man, besides these loops, such as exist in the lower animals, 

 is not certainly determined. 



268. 



Fig. 269. 



Form of the terminating loops of the nerves of the muscles. 



The trunks entering the muscles are composed mostly of the thick 

 (medullated) nerve fibres; there being only twelve of the finer, on 

 an average to one hundred of the 

 larger. (Volkmann.) In the in- 

 terior of the muscle they, how- 

 ever, become smaller ; so that the 

 fibres of the terminal plexus are 

 only T2 W to T5 V<5- of an inch in 

 diameter. Sometimes the gra- 

 dual attenuation can be seen un- 

 der the microscope, showing that 

 sometimes at least this diminu- 

 tion is not due to division. Kol- 

 liker finds them to present at last 

 the appearance of the so-called 

 sympathetic fibres ; becoming 

 pale, with a simple contour line 

 disposed to form varicosities. 

 Thus, though no neurilemma 

 could be distinguished, the dark 

 border shows that they are not 

 free axis-cylinders, or non-medul- 

 lated fibres, such as are seen in other terminations of nerves. 



Divisions of the nerve-fibres in muscle. (Mag- 

 nified 350 diameters.) A. Double division from 

 the omohyoid muscle in man. a, a, a. Neuri- 

 lemma. B. Division of a nerve from a facial 

 muscle of the rabbit into three apparently pointed 

 twigs. (Kollilter.) 



