TOPOGRAPHY <>!' Till-: 



877 



The lino marking out the inforo-latoral border c. immonce- at (ho posterior enu in tlio p: 

 ipbemoida] ,-uture, whence il passe.- downward-, in front of I hi 1 spheno-M|Uainous suture, totlio 

 infra-temporal ere.- 1 (pterygoid ridge ' ; there it turns backward- :unl. running parallel with and 

 internal to the /.ygomaUi ! i,e root of (he xygoma. and. a-eondinn .-lightly, it p. 



alMivo the external auditory meatus. ( '<intiiiui:i^ backwards with an inclination upwards it 

 reaches a point immediately al>ovo tin . and, crossing the lower 



part of the lamhdoid suture and the Miperior curved line, it pa c.- in ward- to the lower part of the 



external occipital protuberance. 



The supero-me-ial hord.-r of the hemisphere is defined l>y a line which runs from the nation 

 tnthe inion. This line should lie drawn about ."> mm. to the outer side of the sagit tal suture, 

 because the mesial .!' i lied by the -uperior -agiital -inns, anil it shoulil be further awav 



Irom the middle, line on the right than on the lelt side, because the sinus tends to lie more to the 

 right side. 



Tin- area of the skull wall enclosed by the three lines which mark the positions of the super- 

 ciliary, infero-latoral. and the ial borders of the cerebral hemisphere is formed by the 

 vertical plate of the frontal bone, the parietal bone, the great wing of the sphenoid, thesquamous 



FIG. 651. DRAWING OF A CAST OK THE HEAD OF AN ADULT MALE. 

 (Prepared by Professor Cunningham to illustrate cranio-cerebral topography.) 



CKXTttAL 



OtTBM- 



ru;n:i \i. 



POSITION OF 

 PARIETAL 

 EMINENCE 



K.VTK\.H. 



P1R1BTO- 



ttri'll'l I \l, 



nssuas 



POSITION OF 

 FflONTAL EMINENCE 



part of the temporal, and the upper section of the supra-occipital segment of the occipital bone. 



It covers the outer Mirlaee^ of the frontal, parietal, temporal, and occipital lol.es anil the fissures 

 and sulci which bound and mark them. 



In every consideration of the to|Kij;raphical relations of the cerebral cyri to the walls of the 

 cranial cavity it must be borne in mind that the conditions are not constant, and that, therefore, 

 the relations are variable. The three main tactor^ U|MIII which this variability depends are 

 sex. and the >ha|x> of the skull. A.- examples of the variations which occur it may be nieiiti 

 that the lateral lissure U higher in the child than in the adult (compare lis.t>."il and (i.VJ). The 

 upper end of the central sulcus is further away from the coronal suture in t lie female and in the child 

 than in the adult male, and in dolichocephalic than in brachycephalic heads. The tingle formed 

 iK'twoen the line "t the central li-suro and the mid-sagittal plane, which averages about (is in 

 the adult, is more acute in dolichocephalic heads, and the external part of the paricto-occipital 

 fissure is further forwards in the child, and pos.-ibly in the female, than it is in the adult male. 



The position of the po.-terior horizontal limb of the lateral fissure'varies even in the adult. 

 Its po>terior part is always under cover of the parietal bone, and it terminates either in front of 

 or below the parietal eminence, but the anterior part may lie above, parallel with, or below the 

 squamo-parietal suture. In the adult the anterior part of the lissure run* upward.- arid back'/ 



