8 4 



NORMAL HISTOLOGY. 



nective 

 spindle 



Intra- 

 fusal 

 fibres 



Sheath. 





tissue surrounding bundles of voluntary muscle- fibres and are long 

 -shaped structures, varying in length from 1-5 mm. or more and in 

 width from . i--3 mm. where broadest. They are 

 widely distributed, being present probably in almost 

 all the skeletal muscles, and are especially numerous 

 in the small muscles of the hand and foot. They 

 have not been found in the muscles of the eye, some 

 of those of the face, those of the pharynx, the intrinsic 

 muscles of the larynx, some of the perineal muscles, 

 and the diaphragm. 



Each muscle-spindle consists of a capsule, com- 

 posed of a few concentric layers of fibrous tissue, which 

 encloses a group of from three to ten, but sometimes 

 as many as twenty, striated 

 B muscle-fibres, medullated 



nerves, blood-vessels and in- 

 terspersed connective tissue. 

 These intrafiisal fibres, as 

 the enclosed muscle-fibres 

 are called, differ from those 

 of the adjacent muscle in be- 

 ing much smaller in diameter 

 and length, markedly tapered 

 towards either end, more 

 coarsely but less distinctly 

 striated and in possessing 

 nuclei within the sarcous sub- 

 stance. The intrafusal fibres 

 collectively are surrounded 

 by a thin special fibrous 

 envelope, the axial sheath, 

 between which and the 

 capsule lies a periaxial 

 lymph-space. Each spindle 

 receives usually several med- 



Ordinary 

 muscle- 

 fibre 



Capsule 



FIG. 118. A, neuromuscular ending; B, neurotendinous 

 ending in longitudinal section, methylene-blue staining. X 

 260. (Drawn from preparation made by Professor Huber.) 



Intrafusal 

 fibres 



Capsule 



FIG. 119. Neuromuscular ending 

 in transverse section. X 370. 



ullated nerve-fibres, which, after incorporation of their fibrous sheaths with 

 the capsule, pierce the latter at various points and proceed to the individual 



