138 PERIPHERAL NERVE TERMINATIONS 



Either one or several nerve trunks enter the spindle, usually 

 near its equator rather than at its poles. The nerve fibres branch 

 repeatedly in the intracapsular connective tissue, and finally pierce 

 the axial sheath as naked processes which form a rich arboriza- 

 tion of terminal fibrils about the intrafusal muscle fibres. Ruf- 

 fini distinguishes three types of terminal nerve fibrils : (1) an- 

 nular, which form rings around the muscle fibres; (2) spiral, 

 which are spirally twisted about the intrafusal fibres ; and (3) 

 dendritic branchings (terminaisons a fleurs), in which the neu- 

 raxes break into numerous irregular processes with laminate ex- 

 pansions. 



Motor end plates for the muscle fibres of the spindle as well 

 as sympathetic vase-motor nerves for its blood vessels have also 

 been demonstrated within the muscle spindles. 



That the muscle spindles are sensory and not motor organs 

 has been demonstrated by Sherington,* who found that they were 

 not affected by the muscular atrophy following section of the pe- 

 ripheral motor neurones, and by Horsley f and others who have 

 found that the muscle spindles are unaffected in cases of extreme 

 muscular atrophy in man. 



III. NEUROTENDINOUS END ORGANS (Golgi end organs, 

 tendon spindles}. These organs occur in the tendons of mus- 

 cles near the junction of the tendon bundles with the muscle 

 fibres. They are fusiform in shape and consist of a thin lamellar 

 capsule of connective tissue which incloses several intrafusal 

 tendon bundles of dense fibrous tissue. A narrow lymphatic 

 space intervenes between the capsule and the intrafusal tendon 

 bundles. 



Nerve fibres enter the spindle and give off several medullated 

 branches which run between the tendon bundles near the axis of 

 the spindle. These finally form naked end fibrils with branching 

 end plates, which surround the tendon bundles in an annular or 

 spiral manner (Ciacio J). Since the structure of the Golgi ten- 

 don spindles closely resembles that of the muscle spindles, they 

 are undoubtedly of similar function. 



IV. In addition to the special motor and sensory end organs 

 described above, Pacinian corpuscles and end bulbs of Krause are 

 also found in the connective tissue of striated muscles. 



* J. Physiol., 1894. f Brain, 1897. 



I Arch. ital. de biol., 1891. 



