208 



NA TURE 



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NOTES FROM THE OTACO UNIVERSITY 



MUSEUM 

 IX. — On the Nomendatiifc of the Brain and its Cavities 

 TN working at the brain of tlie lower Vertebrata, the incon- 

 •^ venience of the received terminology of the cerebral cavities 

 became so manifest, that I adopted the plan ' of distinguishing 

 each cavity by the simple expedient of placing before the syllable 

 cale {ko'i\os, koiA/o) the prefix used for the corresponding division 

 of the brain in the systematic nomenclature adopted in Quain's 

 " Anatomy." Thus, the entire cavity of the mid-brain of fishes, 

 for which the usual names " aqueduct of Sylvius " or " iter a 

 tertio ad quartum ventriculum " were unsuitable, became the 

 mesoeale or cavity of the mesencephalon, the "lateral ventri- 

 cles," the prosoca-les or cavities of the prosencephala, and so 

 on. A similar but more thorough-going reform had been pre- 

 viously and independently proposed by Burt Wilder (^«VHa-, ii., 

 1881, pp. 122 and 133), and adopted in Wilder and Gage's "Ana- 

 tomical Technology " (New York, 1882). Prof. Wilder was 

 good enough to write to me on the subject, and, after some 

 correspondence had passed between us, he pablished an article - 

 giving a full account of the nomenclature he p oposed to adopt, 

 and stating that certain of his terms (e g. neurocale for the entire 

 cavity of the cerebro-spinal axis, and cncephalocale for the entire 

 system of brain-cavities) had been proposed by me. 



The chief features in Wilder's nomenclature are the fol- 

 lowing : — 



(a) The adoption of dicncephalon in preference to the more 

 cumbrous tJialamencefhalon as the systematic name of the 

 'tween -brain {Zwischenhii-n). The former term is given as a 

 synonym by Allen Thomson (Quain's " Anatomy," ninth edition, 

 vol. ii. p. 828), and is used by Rolleston in " Forms of Animal 

 Life." In correspondence with this, the third ventricl ■ becomes 

 the diaeccle {ihalainoccele, mihi). 



(b) The adoption of Quain's name of efencephalon for the 

 cerebellum (llinterhirn), and of melencephalon for the medulla 

 oblongata (Nachhirii). Huxley's term, myclemephalon, for the 

 latter division, is rendered inconvenient, to say the least, from 

 the fact that it is used by Owen to designate the entire cerebro- 

 spinal axis. The fourth ventricle is called the metacale {mvclocccle, 

 mihi), and the cerebellar ventricle the cpiccele {metacale, mihi). 



(c) The word prosencephalon is used in the same sense as by 

 Quain, i.e. as including the whole of the fore-brain proper 

 ( Vordcrhirn). Both Owen and Huxley, on the other hand, use 

 this term as synonymous with cerebral hemisphere, i.e. speak of 

 paired prosencephala. In correspondence with this, the entire 

 cavity of the fore-brain is called the p7-osocoic, and the lateral 

 ventricles themselves /z-ora-fe (prosocales, mihi). 



(d) The unpaired cerebral rudiment of the embryo is distin- 

 guished as the protocerebriini. 



Fig. I. — Diagrams showing three chief stages in the development of the nervous system. A, the neuron is divided into myeloti and ence^kalon, the latter 

 being again divided into the three primary vesicles, firotenceplialon, deiiterencephahn, and tritcnccpkalon. Similarly, the neurocyte, or general cavity 

 of the neuron, is divided into fityetoaete and eficephaloco^le, and the latter, again, into proto-, deutero-, and iriio-ca;les . B, the br.iin now consists of 

 five_ encephalomeres, the proslhi-, dt-t vies-, ep-j and met-ertcephala, containing respectively the prostkio-, dia- jjieso-, cpi-, and meta'Cifles. c, D, the 

 brain has assumed its permanent form, and is shown in c in vertical, in D in horizontal section The prosthiencephalon has sent out paired 

 prosencephala, a small unpaired ^orHon, t)vt basicercbriim {It.ct^r), htrnf". left, the latter being bounded in front by the lamina terminalis (/«?«. ^t-r/w) 

 Each prosencephalon has further given rise to a rltinCJtcepttalon. Similarly, the prosthiocoele now consists of unpaired aitlce and of paired proso and 

 rhino-cales (prsca, rh.ca), the former communicating with the aula by the foramina of Monro, or ports (y5>r.jl/.). The diaccele is continued 

 above into the conarium {.con), below into the infundibulum (/«/) with the hypophysis {hyp\ The mesencephalon consists of an unpaired ventral 

 basi-optinis{b.op>t),^x\&oKy^\x^d. optencephala ; its cavity of a median r/^r, and of paired ('/^(^ftf'.V.j, which communicate with the iter by the /^-Ztf-. 

 The epencephalon is divided into a dorsal portion, the cerebellum, or epencephalon proper, and a ventral division, the bast-cerebetlum {p.cbt), 

 containing a cavity, the atrium (a/r), which communicates with the epiccele proper, or cavity of the cerebellum, by the ostium {ost). The metencephalon 



and metaccele (tuet.ea') ha 



ndergone but little alteration. 



(t-) The unpaired portion of the fore-brain, left by the 

 budding-ofir of the cerebral hemispheres, is not specially named, 

 but its cavity is termed the aula. This is a large and distinct 

 cavity in some sharks {eg. .Scymnns, Fig. 2), but in the higher 

 forms becomes the Y-shaped passage between the third and the 

 lateral ventricles. This passage is sometimes spoken of as the 

 "foramen of Monro," but the latter term is more correctly 

 applied to the aperture between each of its anterior limbs and 

 the corresponding lateral ventricle : this aperture Wilder calls 

 the pn-ta. 



(y ) The specialised cavities in the optic lobes of Amphibia 

 and Sauropsida are called optocceles, the name iter (abbreviation 

 of ' ' iter a tertio ad quartum ventriculum ") being retained for the 



,d Embryology of Scytnnus lichia" Traits. 

 "A Course of Instruction in Zootomy," 



^ " Notes on the Anatomy 

 N.Z. Inst. XV. (1882), p. 2i 

 London, 1884. 



'^ " Encephalic Nomenclature," Ne^i York Medical Journal, xli. ( 

 pp. 325 and 354. 



unpaired portion of the mesoccele or entire cavity of the mid- 

 brain. The iter cominunicates with each optocoele by a sTnall 

 aperture, the py la. No name is given to the ventral portion of 

 the mesencephalon after formation of the optic lobes, i.e. the part 

 usually known by the awkward plural designation crura cereWi, 



(g) The ventral portion of the epencephalon, the fibres of 

 which become the pons Varolii in mammals, is called the /r<r- 

 oblongata, the word post-oblongata being used as a synonym for 

 metencephalon or medulla oblongata in the restricted sense. 



(//) The entire cerebro-spinal axis is called the tieuron, its 

 cavity the neurocale. 



(i) The name eti .-epkaloccele is applied to the entire system of 

 brain-cavities, or to the single cavity of the undivided embryonic 

 encephalon. 



[k) The name niyeloccele is applied to the central canal of 

 the myelon. Ttiis cavity is also distinguished into a lumbar 

 dilatation, the rhombocale (sinus rliomboidalis) and a contracted 

 portion, the syringoccele. 



