30 



HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY I 



in the laboratory which were many and varied. His 

 work on the spinal roots led him to follow the differ- 

 entiation of function into the spinal tracts where he 

 found that pressure on the posterior columns, but not 

 on the anterior, caused signs of pain. One other aspect 

 of Magendie's work on the spinal cord should be 

 mentioned, his rediscovery of the cerebrospinal fluid 

 (157). Sixty years earlier this had been seen and 

 described by Cotugno (158), at that time a young 

 physician in the Hospital for Incurables in Naples, 

 but his monograph had stirred no general interest 

 though it helped to win him the chair of anatomy at 

 the university. Magendie described the forainen 

 known by his name, but oddly revived a valve-like 

 role for the pineal as controller of this opening. He 

 thought the fluid was secreted by the arachnoid mem- 

 brane, and it was many years later that its origin in 

 the choroid plexuses was discovered. A later pamphlet 

 by Magendie (159) on the cerebrospinal fluid has 

 some fine illustrations by H. Jacob. 



Once the differentiation of function between the 

 anterior and posterior roots had been accepted, the 

 finer points as to which regions were inner\ated by 

 their fibers began to occupy the physiologists. The 

 question as to whether all the fibers of an anterior 

 root served the same or many muscles was paralleled 

 by its corollary as to whether one muscle received 

 fibers from one or many roots. That the last arrange- 

 ment is the correct one was first clearly shown by 

 Eckhardt (160) in frogs and by Peyer (161) in rabbits. 

 Both were working in Carl Ludwig's laboratory. The 

 definitive demonstrations came later from Sherring- 

 ton's (162) careful analyses, mostly in the monkey, 

 from which he concluded that '"the position of the 



157. Magendie. Memoire sur la liquide qui se trouve 

 dans le crane et canal vertebral de Thomme et des 

 animaux mammifiercs. J. physiut. cxph. el path. 5: 27, 

 1825. 



158. Cotugno, Domenico (i 736-1822). De Ischiade Nervosa 

 Commentarius. Naples: Simonios, 1764; a portion has been 

 translated into English. A Treatise on the Nervous Sciatica^ 

 or Nervous Hip Gout. London: Wilkie, 1775, p. 14. 



159. Magendie, F. Rkherches physiologiques et cliniques sur le 

 liquide cephalorachidien ou cerebro-spinal. Paris: Mequignon- 

 Marvis, 1842. 



160. Eckhardt, C. Uber Reflexbcwcgungender vier letzten 

 Nervenpaare des Frosches. ^Ischr. rat. Med. (ist series) 

 I : 281, 1849. 



161. Peyer, J. Uber die pcriphcrischcn Endigungen der 

 motorischen und sensibelen Fasern der in den Plexus 

 brachialis des Kaninchens eintretenden Nerven wurzeln. 

 Zlschr. rat. Med. (ist series) 4: 67, 1853. 



162. Sherrington, Charles Scott (1857- 1952). Notes on 

 the arrangement of some motor fibres in the lumbosacral 

 plexus. J. Physiol. 13: 621, 1892. 



nerve-cells sending motor fibres to any one skeletal 

 muscle is a scattered one, extending throughout the 

 whole length of the spinal segments innervating that 

 muscle." 



Tracing of the fibers of the sensory roots was in- 

 trinsically more difficult. Tiirck's (163) studies in 

 X'ienna had indicated the complexity of sensory inner- 

 vation in the dog, and Herringham (164) had found 

 the segmental relationship with the vertebrae; but 

 again it was Sherrington (165) who, using the reflex 

 as criterion of the existence of afferent fibers, un- 

 ravelled the phenomena of overlapping of segmental 

 cutaneous innervation. Until the time of Sherrington 

 it had been thought that the motor fibers to a given 

 muscle were derived from the same spinal segment 

 that received the sensory inflow from the skin sur- 

 rounding it. This was particularly the view of Krause 

 (166). Sherrington's mapping of myotomes and der- 

 matomes showed this rule to be erroneous. 



.Sherrington's development of a comprehensive 

 theory of reflex action could scarcely have been en- 

 visaged before the sensory endings in muscle had been 

 discovered. This advance was mainly the work of 

 Rufiini (167, 168) who in 1892 identified as sensory 

 organs muscle spindles, tendon organs and Pacinian 

 (169) corpuscles. These structures had been seen and 

 dcscriljed by others, but their function had not been 

 appreciated. The need for an apparatus for muscle 

 sense had been felt by Charles Bell (170) in order to 

 convey "a sense of the condition of the muscles to the 

 brain," and he postulated "a circle of nerves," saying 

 that "every muscle has two nei^es, of different proper- 

 ties supplied to it." That sensations are aroused by 



163. TiJRCK, Ludwig (1810-1868). Uber die Haut-Sensibili- 

 tatsbewirke der enzelnen Riickenmarksnervenpaare. 

 Denkschr. Akad. Wiss. 29: 299, 1868. 



164. Herringham, VV. P. The minute anatomy of the brachial 

 plexus. Proc. Roy. Soc, London, ser. B 41: 423, 1887. 



165. Sherrington, C. S. Experiments in examination of the 

 peripheral distribution of the fibres of the posterior roots 

 of some spinal nerves. Phil. Trans. 184 B; 641, 1894. 



166. Krause, Fedor (1856-1937). Beitrdge zur Neurologie der 

 oberen Extremildt. Leipzig, 1865. 



167. RuFFiNi, Angelo. Di una particolare reticella nervosa e 

 di alcuni corpuscoli del Pacini che si trovano in conces- 

 sione cogli organi musculo tendinei del gatto. Atti R. 

 Accad. Lincei 1 : 12, 1889; French translation in: Sur un 

 reticule nervcux special et sur quelques corpuscles de 

 Pacini qui se trouvent en connexion avec les organes 

 musculo-tendineux du chat. Arch. ital. biol. 18: loi, 1893. 



168. RuFFlNi, .\. Observations on sensory nerve endings in 

 voluntary muscles. Brain 20: 368, 1897. 



169. Pacini, Filipfo (181 2-1883). -^uovi organi scoperti net 

 corpo humani. Pistoja: Cino, 1840. 



170. Bell, C. On the nervous circle which connects the volun- 

 tary muscles with the brain. Phil. Tram. 2: 172, 1826. 



