810 THE SPINAL CORD. 



from this system pass in large numbers toward and into the base of the 

 posterior horn and Clarke's column. 1 



The Spinal Grey Matter. 



In the grey matter of the spinal cord lie the trophic centres, i.e. cell- 

 bodies or perikarya, for all the intrinsic spinal and spino-encephalic 

 paths ; also all the spinal synapses. 2 



Scruff 3 supposed that " pain "-impulses ascend along the grey 

 matter to the brain. The path for impulses connected with pain does (see 

 " Cutaneous Pain," this vol., p. 965) plunge into the grey matter very soon 

 after entering the cord ; it then, probably, after a short course emerges 

 into, in part at least, the opposite lateral column. The short in-and- 

 out traverse of the grey matter by this path is probably typical 

 of all paths in the grey matter ; they are probably all quite short. 4 If 

 all synapses lie in the grey matter, each path where it involves a 

 passage from one link to another in a neural chain must enter the 

 grey matter to establish its linkage ; it probably soon emerges thence 

 again. It is unlikely that there are spinal paths built up of any 

 large succession of spinal links. Just as it seems that the spinal grey 

 matter enters into the composition somewhere or another of every 

 efferent path in the cord, including that of the simplest possible 

 reflex, so it enters into the composition of every afferent path with 

 the single exception of the remarkable long direct path of the dorsal 

 column that first breaks into grey matter in the bulb ; and there- 

 fore, speaking in conformity with the somewhat artificial scheme of 

 delimitation generally employed, above the cord itself. 



Very different in its appearance as regards detailed structure 

 from the general spongiosa, is that portion termed gelatinosa which 

 caps the dorsal horn. This gelatinosa probably forms an end-nucleus 

 for a cell-system connected with some one particular set of sense organs. 

 The gelatinous formation extends without break throughout the region 

 of each segmental nerve, from the cranial fifth to the lowest coccygeal 

 inclusive. It is extremely developed in the region of ending of the 

 afferent root of the fifth cranial and in the spinal regions corresponding 

 with the limbs. It is therefore probably less concerned with sense 

 organs of viscera and muscles than with those of the skin ; it may 

 contain the first synapse for cutaneous pain. The paralysing effect of 

 blood stasis in the lower part of the cord on cutaneous sensation agrees 

 with this view. 5 Certain chemical reagents, though acting but slightly 

 on the peripheral nervous system with its adjunct motor endings and 

 sense organs, extraordinarily affect the spinal cord. The difference 

 probably rests on the grey matter of the latter with its abundant 



1 Schafer, loc. cit. 



2 It is possible that some synapses occur outside the grey matter. Further, Clarke's 

 cell- column lias a number of cells of aberrant position, especially in man, lying in the 

 afferent root-zone. 



3 "Physiologic," Lahr, 1858, Bd. i. S. 251 ; Arch. f. d. ges. Physiol., Bonn, 1882-1883, 

 Bde. xxviii., xxix., xxx. ; also Wundt, "Grundziige d. physiol. Psychol.," Leipzig, 1893, 

 Bd. i. S. 110-112 ; and Funke, Hermann's " Handbuch d. Physiol.," 1880, Bd. iii. S. 2. 



4 Ciaglimski {Neurol. Ccutralbl., Leipzig, 1896, Bd. xvii.) finds degenerative evidence 

 of a long ascending path in the central part of the spinal grey matter, but his observation 

 stands unconfirmed. 



■' Miinzer and Wiener, Arch. f. exper. rath. u. Pharmakol, Leipzig, 1895, Bd. xxxv. 

 S. 113; Langendorff, Arch. f. d. ges. Physiol., Bonn, 1898, Bd. lxxi. S. 401. 



