BRA 



Tlie fpinal marrow is covered externally by a proJualon 

 of duo m ter, which eitends from the great occpUal ora- 

 nenU-X bottom of the facrum, conneaed throughout 

 to the ve tebral canal, by a loofe cellular and adjpolc fub- 

 h ce and al the intervals of the vertebra, by the cou.cal 

 proccfs which it attaches to the commencemen of the 

 Lrv" The tunica arachnoidea is much more loolely con- 



ea dto thevalcular membrane than .t .s m he bra . 

 The piu mater furrounds the fpinal marrow very clofe y, m- 

 fomueh that, in making a tranfverfe teaion, the medullary 

 S^e protrudes from the cut furface. The medulla fpma- 

 ^ CO, n aed at the hde to the dura mater by fmall por- 



; of membrane, which are found between the antenor 



d- turn For delcriptions and reprefentatjons of the me- 



'on 'of - Mom'o's obfervations on the nervous fyf- 



tem" and Fratfcher defcript.o meduUx fpn^ahs cum tcone, 



Erlang. 1783. 



SiruSi/re of the nerves. 

 The nerves are foft, white and fibrous chords, nearly oi a 

 cylldrlcrLpe, arifrng from the br.in, or :.edu a pma 

 lis When they leave the bram, the pia mate, colleas the 

 fibres nto larger or [mailer fafciculi, vvh.ch can be fee, 

 S O.U any priious preparation, by mak.ng a lo^g.tudma 

 or t,-anfverfe feaion of a pretty la,-ge t,-u.,k. Where tie 

 rlrves penetrate the dura mater, they are hrmly conneaed 

 o h 'ma,-g>nof the openmg and have been fnppoM to 



recerve an r.ternal coat f™"^ ^^^^^ ■^^'"^T,^, ;J^fii" 1^ 

 is onlv true of the optic nerve. I he medulla, y ^ila"^"]^ "' 

 the nerves are covered by a vafcular membrane called by 

 R il , u lema, which detLhes proceffcs from itsumerfu,- 

 fac to urro nd and inv.ft the fm.ller d,v,fions and fibres 

 of \he medulUuy fubtVance. ^y .mme,fu,g a^.er^. n al 

 kah, the medulla of the ne,ve ,s drffohed, ^'"^ ^e cont^,,xa 

 .nen'.bvanous tubes formed of neurdema are le • Ac.os 

 d,irolve the neu,-ilema, and leave ^ -jfj "^ y^]"? ,^ 

 Thefe organs receive a confiderable fupp) ot blcua m m 



Slels w4h ramify ^^ ^^ ^^^'.^^f'^^S- 

 t^^Sr:^^^ :f'rn::"ri;refolv.d on us 

 fu ace in o a loofe fublbnce, which conneas the nerve .0 



T:T: Turd^ S^Tttfe'^^HittVhLs: . whoUy 



- : , • a r' M -rS>-l "bfervations, however, Ihov 



^ v^n Verfe lh-i:e in the fubllance of nervous trunks, of 



rm<Ir " d tp ;:nce than the reft, which d.fappear on 



ftr thin" the"e,-ve, and are reftored by agam lctt,ng ,t 



We fh s appearance charaaerizes the fma left per ep- 



Sk fibre and enables us to drlUngu,^ them i,-om mufck, 



- tendon &c. Fontana probably alludes to this c,rcum- 



We when he calls the' nervous fibres, wav.ng cyhnder . 



ThefibrI do not p.-oceed in ailraight unmterrupted courfe, 



Sioufreqrltlywrth each other, fo that, accord,ng to 



ik i ne expel iiiiciiv- v/* *--.-, — 



• T;",,-;,- ^cu] to diffolve its membrane, ftiews this, 

 ^^w^lUs'S^picIloSlc.vat.n. A nerve, when divided 



BRA 



in the living fubjea, retraas: the medulla h "P'^^d f"-"™ 

 its extremrlies by the coutraa.on of ,ts "J.^^-b'-ane , the 

 form of globules, mo,-c cop.oufly, «"°'-.d"--g ° } '"^''af"' 

 from the upper, than the lowerend. 1 ''J^ P^°'™''""f .'^^^ 

 medulla,-y matter takes place u, a lefs degree " t^e dead 

 fubica. If a nerve be cut m a hv.ng animal, and he be 

 killed at fome period afte, the operauon, it wil be found. 

 that the divided ext.cmities have fwollen „>lo a fmall tuber- 

 c k, and that they are conneaed by a-ncw formed n,atter. 

 Ar atomUls have difputed greatly, whether or not th,s were 

 real nerve, whether it was a regeneration of medullary mat- 

 er. As it would not probably be very eafy to deoUe th 3 

 nueftion bv merely anatomical teft,mony, f-om our 

 STc'e of\h"'.inIte ftruau,-e of thefe organs, tt appears 

 1ft ph.lofophical to inquire, whether the new n^^tter vn^ 



perfonn the funaions of a ^^^^^^ ' r\V^'''^''\uT iTZ 

 Ltely proved bv the experiments of Dr. Harghton, in the. 

 firft part of the PhilufophkalT,anfaa>ons for the year 1795- 



n fome pa,ts of the' nervous fyftem,httk tube.-cles or 

 knots, calkd ganglia, are found in the courfe of the nerve 

 and are ufually formed by the concurrence «/ f^^^^^' 

 branches. Thefe bodies are of various figu,-es, but gene-- 

 rally flattened. They partake more of the red colour, 

 t£ Z trunks of the'nerves on which they are formed 

 as *hey poffefs mo,-e numerous blood-veffels. They contam 



everaf rfervous fibres, diftinguiftied by their ?«"■-£-- 

 te,-iftics, and fur,-ounded by a pretty firm vaicula, fubftance. 

 Th fibres communicate in thefe bodies, and each nerv 

 which goes from a ganglion, is faid to Vf^J^J-'^^^ 

 of every other nerve which oins it. For a fuith.er aecou, t 



o\ the Ilruaure of nerves, the fo"--"gr-tr de Stiu "• 

 fulted- ReilExercitationes Anatomicx; P.ochaflca de btiuc 

 tuid Ni'S-um; Monro's Obfervations on the btruaure 

 and Fuiaions of the nervous Syftem ; Arneman verfuche 

 kbehdigen Thie,-en ; Fontana T,-a,te iur le Vemn d^ a 

 Vipere, &c. ; Haafe de ganglns nervorum ; Scarpa An- 



of1heb,-.in and nerves, we proceed m conformity to the 



Tlie circmlt.on. «h,ch h«e mJucrf 'l'" '» ''«'™ 



inff and voluntarv motion a,-e fufpended. zdly, i lie laue 

 pE tbe fa, in Lk .«. .0 «1"* ",;L'""','f" d'f 



l£^S^:™Ss':^errr :r jb » ;. 



A«3 pik «to !«.= Utbur limbs uktn .11, ™ fcm^^ 



