CRANIO-CEREBRA L TOPOGRA I'll Y 



10H7 



iindi-r tlie following licailiuL^s: A. Relation of the brain as a whole to the 

 skull. 15. Relation of the chief sulci and convolutions to the skull. ('. 

 Localisation of the chief sulci and convolutions, iitlon- alluding' to tin- 

 above, it is necessary to say distinctly that tlie following surface-markings and 

 p(jints of guidance are only approximately reliable, for the following reasons: (1) 

 In two individuals of the same age and sex the sulci and convoluti<tns an; never 

 ])recisely alike. (2) Tlie relations of the convolutions and sulci to the surface 

 vary in different individuals. (3) That as the surface area of the scalp and outer 

 aspect of the skull are greater than the surface area of the brain, and as the 

 convexities do not tally, lines drawn on the seal}) or skull cannot always corres])ond 

 preeisely to cerel)ral convolutions or sulci. It results from the above tliat when a 

 delinite area of the surface is said to correspond accurately in any individual to :i 

 definite area of the brain surface, this result has l)een correlated from many 

 examinations; and that as surface-markings, shape, and })rocesses of skull ai.d 



Fig. 664. 



-The Outline ok tiik liRAix and its Fissttkks in Relation to the RrTiHEs 

 OF THE Skull. (Cunningham.) 



V. p.B./ l<>v ''"''' v„ 



% .sf : 



j-^ 







"cr^j 



s M. Supraciliary niarfjin of the oerehiiini. i.l.m. Iiirtro-lateral margin of tlie cen-hrnm. 

 L.s. Po.sition of higllt'St part of the arrli ol tile lateral sinus, i:. Fissure of Kolando. s'. Anterior 

 horizontal limb of .*>\ivian lissure. s^. Anterior ascending limb of Sylvian fissure, .s^ I'osterior 

 horizontal limb of Sylvian ti.s.sure. P.H. Pars ba.silaris of the inferior frontal convolution. r.T. 

 Pars triangularis of the inferior frontal convolution. P.O. Pars orliitalis of the inferior frontal 

 convolution. 



arrangement of brain surface are all liable to varintions in difTcrmt individuals, the 

 sui-L't'on must allow for these variations by removing more than tliat definite area of 

 skull which is said to corresjxMid exactly to that i>art of the lirain which he desires 

 to eXpo>t\ 



A. Relation of the brain as a whole to the skull (figs. (W)4 and (\(\(\^. — 

 Traced from bd'orr backwards, tJic Ininr Irn I oj' oirli rnrhml htiiiLsjilH ir would follow 

 a line across the forehead, slightly curved upwards al)ove the eyebrows, cr(»ssing 

 from the forehead to the temjile immediately above the external angular process of 

 th(^ frontal. It then descends slightly alonga line now convex forwards in tlie front 

 of the tem]»oral fo.'S.-ia to about the centre of tlie upper margin of the zygomatic 

 arch. From this ]><»int a line should be drawn just above the external au<litory 

 meatus to the external oceijiital jirotubcrance. To trace tJM' lower levd of the 

 brain more jirecisclv on the skull, the chalk would start from tiic lower ])art of the 

 glabella; thence the line i)ursues a course, slightly curved ui)wards, about a third of 



