26 THE INVOL UNTAR Y NER VO US S YSTEM 



or main chain of sympathetic ganglia. Evidently this sacral out- 

 flow of fine medullated nerves corresponds in position to those 

 thoracico-lumbar rami communicantes, which are designated by 

 the name of the abdominal splanchnic nerves, rather than to 

 those which connect with cells of the main sympathetic chain. 

 For this reason, and because the name nervus erigens only ex- 

 presses a part of the functions of this sacral outflow, I originally 

 called this nerve the pelvic splanchnic nerve. There are however 

 many advantages in confining the use of the word splanchnic to 

 fibres connected with cells of the sympathetic nervous system, so 

 it is better to leave out the term splanchnic and call the nervus 

 erigens, as Langley has done, the pelvic nerve. 



Thus it is evident that there exist two distinct outflows of 

 efferent fine medullated fibres from the spinal cord to motor 

 ganglia outside it, the one limited to the thoracico-lumbar region 

 and the other to the sacral region. 



I then proceeded to examine the anterior roots above the 

 thoracic region to see whether there was any evidence of groups 

 of fine medullated fibres in them, and found no trace of anything 

 of the kind in any of the anterior roots of the cervical nerves. But 

 it must be remembered that in this region of the spinal cord there 

 are three roots, not two, a dorsal root, a ventral root, and a lateral 

 root. The system of lateral roots forms the spinal accessory 

 nerve, a nerve which is distinctly motor in function ; I therefore 

 cut sections of the roots of the spinal accessory and .-found in 

 the uppermost roots distinct evidence of an outflow of very fine 

 medullated fibres. Tracing these to their destination, I found 

 that they all passed into the internal branch of the spinal 

 accessory to join the vagus nerve, leaving the external branch, 

 which is the nerve to the trapezius and sterno-cleido-mastoid 

 muscles, free from admixture with such fine fibres. These upper 

 rootlets of the spinal accessory pass imperceptibly into the root- 

 lets of the vagus, adding more and more of the fine medullated 

 fibres to that nerve, which is one of the main nerves of the 

 organic system. Here then was evidence of a cranial outflow of 

 nerve fibres of the same kind as those in the thoracico-lumbar and 

 sacral regions. Further investigation showed that such nerves 

 as the nervus tympanicus, running from the glosso-pharyngeal 

 to the otic ganglion by way of the lesser superficial petrosal, the 

 chorda tympani, running from the facial to the submaxillary 



