686 SYMPATHETIC AND OTHER SYSTEMS OF NERVES. 



Several subsequent observers pointed out that the medium and large 

 fibres of the sympathetic, so far as they could be followed, ran past the 

 ganglia and did not end in them. But no great attention was paid to 

 the size of sympathetic nerve fibres until Gaskeli's work in 1887. He 

 argued that all efferent " visceral " fibres are small fibres. And this 

 view we may accept. The only point that can be urged against it is, that 

 the actual termination of many of the medium and large fibres is not 

 yet known. 



The converse of this view, namely, that all small efferent medullated 

 fibres are " visceral," i.e. autonomic, cannot at present be affirmed. Thus 

 the anterior roots of the nerves to the limbs, which have not been 

 shown to exercise any autonomic function, contain some small fibres, 

 though but few. 



A further matter, on which it is premature to make any dogmatic 

 statement, is as to the size of the afferent fibres of the sympathetic and 

 other parts of the autonomic system. It may, I think, be regarded as 

 certain that the afferent fibres occurring in the sympathetic are not 

 fibres of any one size. Small medullated fibres can be traced into the 

 white rami of the sympathetic from the posterior roots of the spinal 

 nerves ; and the nervus accelerans, which consists exclusively or almost 

 exclusively of non-medullated and small medullated fibres, gives, on 

 stimulation, all the usual reflex effects. On the other hand, in the cat 

 many of the larger nerve fibres of the sympathetic trunk can be traced 

 into Pacinian bodies. And the depressor nerve, which is especially a 

 nerve connected with autonomic reflexes, consists in great part of medium 

 and of large nerve fibres. It is not unlikely, as regards the sympathetic 

 system, that the medium and large fibres end in the serous membranes, 

 and give rise to local pain, and that the small fibres end in connection 

 with unstriated muscle and glandular tissue, and give rise to referred 

 pain (cf. p. 689). But until the actual endings of the several afferent 

 fibres have been ascertained, we cannot even say which are directly 

 connected with autonomic reflexes, and which only indirectly by way of 

 the somatic system. 



It may be mentioned that the cutaneous nerves contain numerous small 

 fibres which run to them direct from the spinal nerves. 



Afferent Autonomic Fibres. Keferred Pain in Visceral 



Disease. 



Connection of afferent sympathetic fibres with spinal ganglia. 



— Some histological observations by Cajal and by Dogiel have been taken 

 to imply that the afferent sympathetic fibres have a special connection 

 with the spinal ganglia. 



Cajal has described large nerve fibres as passing from the sympathetic 

 chain, and giving off branches which penetrate between the cells of the 

 spinal ganglia ; and he suggests that these fibres form nerve-endings 

 around the cells. Dogiel x traces small medullated and non-medullated 

 nerve fibres from the primary ventral division of the spinal nerve into 

 the spinal ganglion. He considers that these fibres arise from " sensory " 

 cells of the sympathetic ganglia. He finds that the fibres divide and form 

 pericellular endings, and as a rule, if not always, in connection with a new 



1 Internal. Monatschr. f. Anat. v. Physiol. , Leipzig, 1897, Bd. xiv. In this paper, 

 references to other observations bearing on the question will be found. 



