314 MICROSCOPIC ANATOMY OF THE ORGANS. 



this substance. Those who claim that the end arborization is 

 under the sarcolemma, consider the granulosa to be a collection 

 of sarcoplasm. Others, on the contrary, who believe that the 

 axis cylinder ends on the sarcolemma, regard the granulosa as 

 a product of the neuroplasm. Nuclei are present in this sub- 

 stance, and are said by some to belong to the muscle, and by 

 others to the sheath of Schwann. Each muscle fibre possesses 

 usually only one motor nerve- ending. Where, however, more 



FIG. 237. 



-End arborisation 



Granular led_ 







^^M 



"5 



- Mnxcli 1 Jib re 

 Nerve fibre f 



s 



Motor nerve-endings in the fibres of a rat's abdominal muscle. In the upper fibre two 



end plates are to be seen. 



than one nerve fibre approaches a muscle fibre, there are pres- 

 ent in the latter two or more nerve-endings (Figs. 235 and 

 236). Often, on the contrary, one nerve fibre innervates two 

 muscle fibres (Fig. 229). 



(6) /Sensory 



Muscle Spindles. These structures were described first by 

 v. Kolliker as bundles of small muscle fibres closely related 

 with nerve fibres. They were called by him muscle buds 

 (Muskelknospen). Later on, Kuhne observed them, and pro- 

 posed the name now in use. Since this time they have been 

 frequently found and regarded variously as growth centres, as 

 pathological structures, and as sensory nerve-endings. At the 

 present time they are regarded usually as sensory end organs, 

 as proven by the investigations of Kerschner, Ruffini, and Sher- 

 rington. It has been suggested that their function is connected 

 with the muscle sense. The following account is based on a 

 description given by Huber. 



