NEKVE ENDINGS IN MUSCLE AND TENDON 135 



At the surface of the muscle cell the nerve fibre loses its med- 

 ullary sheath, its neurilemma becomes continuous with the sar- 

 colemma of the muscle cell, and its naked axis cylinder divides 

 into two to five branches, which end, often after repeated subdi- 

 vision, in flattened terminal disks, distributed in mammals over a 

 limited, in amphibians over a broad area, but which never com- 

 pletely encircle the cylindrical muscle cell. 



The terminal expansions of the neuraxis rest upon a granular 

 sole plate which contains many ovoid nuclei, the sole nuclei. The 

 nature of these nuclei is somewhat uncertain. By those who 

 consider, as is now generally accepted, that the nerve endings lie 

 within the sarcolemma of the muscle fibre, the nuclei are pre- 

 sumed to be derived from the muscle cell and the granular sub- 

 stance of the sole plate is regarded as a modified portion of the 

 sarcoplasm. Some authors (Kolliker, Krause) regard the end 

 plates as lying on the muscle cell rather than within the sarco- 

 lemma, but the studies of Huber and De Witt, * as also those of 

 many other observers, would seem to have satisfactorily settled 

 this question in favor of the intramuscular interpretation. In 

 this connection it is interesting 

 to observe that motor end plates 

 were discovered by Doyere in 

 those muscle cells of insects 

 which are not provided with a 

 sarcolemma. In these cells, as 

 in the muscles of many verte- 

 brates, the entrance of the nerve 

 produces a distinct eminence 

 on the surface of the muscle 

 fibre which is known as the 

 eminence, elevation, or hillock 

 of Doyere. 



II. MUSCLE SPINDLES 

 (Neuro-muscular spindles, neuro- 

 muscular end organs). These 

 are sensory nerve endings which 

 are concerned with the so-called 

 muscle sense and are found in 

 nearly all the skeletal muscles. 



FlO. 135. A MUSCLE SPINDLE FROM THE 

 PSOAS MAGNUS OF MAN. 



Jf, intrafusal muscle fibres; 2, nerve 

 fibres ; 3, axial shealh ; h connective tis- 

 sue capsule ; 5, muscle fibres of an adja- 

 cent fasciculus ; 6, peri-axial lymphatic 

 spaces ; 7, blood vessel. Hematein and 

 eosiii. x 470. 



* J. of Comparat. Neurol., 1898. 



