86 



NORMAL HISTOLOGY. 



Xi-rve 



axis-cylinder, formed of irregular varicosities and club-shaped ends. Usu- 

 ally each muscle-fibre is provided with a single motor end-plate, which may 



lie at an equal or unequal dis- 

 tance from the ends of the fibre. 

 Exceptionally two end-plates are 

 found on one muscle-fibre, in 

 which case the end-organs usu- 

 ally lie near each other. 



Endings in Involuntary 

 Muscle. The terminations of 



FIG. 120 Motor nerve-endings in striated muscle; bundle 

 of nerve-fibres separates to supply the individual muscle-fibres. 

 X 135- 



FIG. 121. Motor nerve^nding 

 in striated muscle ; terminal ar- 

 borization of axis-cylinder lies 

 beneath sarcolemma embedded 

 in granular sole-plate. X 500. . 



the sympathetic axones supplying the nonstriated muscle are comparatively 

 simple. The cell-bodies of the neurones contributing the immediate fibres 

 of distribution to visceral muscle usually occupy the 

 nodal points (microscopic ganglia) of plexuses within 

 the walls of the organs, from which bundles of non- 

 medullated nerve-fibres extend to and surround the 

 muscle-bundles. Entering the latter, the nerve-fibres 

 divide into delicate varicose threads that pass between 

 the muscle-cells, parallel with their long axes. As they 

 course within the intercellular sub- 

 stance, the varicose fibrils give off 

 short lateral branches that end, as 

 does also the parent fibril, on the 

 surface of the muscle-cells in minute 

 terminal knobs. 



Endings in Cardiac Mus- 

 cle. These, also the terminations 

 of sympathetic neurones, include 

 varicose nerve-fibrils which may be 

 followed between the muscle-fibres. 

 During this course side branches arise 

 which, as well as the main fibril, ter- 

 minate on the muscle elements in 

 endings of varying complexity. In 

 some cases these are merely minute 

 simple end-knobs, resembling those in involuntary muscle; in other cases 

 they are more elaborate and of a group of secondary fibrillae bearing nodular 

 endings, the whole recalling somewhat the motor end-plates in striated muscle. 



FIG. 122 Motor 

 nerve-ending in in- 

 voluntary muscle. 

 (Huber.) 



FIG. 123. Motor nerve- 

 ending in cardiac muscle. 

 (Smirnow.) 



