On pteric sutures and pteric bones in the human skull - DWC - KNAW
On pteric sutures and pteric bones in the human skull - DWC - KNAW
On pteric sutures and pteric bones in the human skull - DWC - KNAW
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637<br />
sqnamosa, 80 that <strong>the</strong> l'egion of <strong>the</strong> fl'ontal process is <strong>in</strong>c1uded <strong>in</strong><br />
<strong>the</strong> alisphenoïd.<br />
Sometimes <strong>the</strong> spheno-parieta1 sutUl'e lies at <strong>the</strong> le\'el of <strong>the</strong> 10we1'<br />
border of <strong>the</strong> frontal process; so that <strong>the</strong> region of this process is<br />
iocl uded <strong>in</strong> <strong>the</strong> parietaJ. Tbe region of tbe frontal pl'ocess of Olle<br />
side cao be <strong>in</strong>cillded <strong>in</strong> <strong>the</strong> frontal, as is pl'oved by a <strong>skull</strong>, which<br />
pJ'esents at <strong>the</strong> 1eft side a ti'ontal procesfl of <strong>the</strong> tempo ral <strong>and</strong> at<br />
<strong>the</strong> right side a symmetrical temporal process of <strong>the</strong> frontal.<br />
If at <strong>the</strong> side opposite to <strong>the</strong> frontal process one Ol' more ossa<br />
epiptel'ica are found, <strong>the</strong> situation c<strong>and</strong> extension of <strong>the</strong>se <strong>bones</strong> are<br />
equal Jo those of <strong>the</strong> ti'ontal process.<br />
We f<strong>in</strong>d o<strong>the</strong>r relations <strong>in</strong> <strong>the</strong> <strong>skull</strong>s with frontal proces sus of <strong>the</strong><br />
second type. Here <strong>the</strong> enlal'gemeu't of <strong>the</strong> squamosal is nearly always<br />
absolutely sJ mmetrical.<br />
<strong>On</strong>ly once did I f<strong>in</strong>d a second type of fl'ontal procees at one side<br />
<strong>and</strong> an ós epi<strong>pteric</strong>um typicum at <strong>the</strong> o<strong>the</strong>l' one.<br />
I suppose th at <strong>the</strong> question aftel' genesis <strong>and</strong> significance of <strong>the</strong><br />
above mentioned two (ypes of ti'ontal processus must be answel'ed<br />
as follows.<br />
The proc. fi'ontalis of <strong>the</strong> first type is to be considereà as <strong>the</strong><br />
homologon of an os epiptel'icUlll typicum. Follow<strong>in</strong>g arguments led<br />
me to this op<strong>in</strong>ion.<br />
In <strong>the</strong> fil'st place it is possible that <strong>the</strong> l'egion of a unilatel'al<br />
proc. - frontalis can be <strong>in</strong>cluded at <strong>the</strong> opposite side <strong>in</strong> one of <strong>the</strong><br />
surl'ound<strong>in</strong>g bon es (sphenoid, f1' on tal, parietai),<br />
In <strong>the</strong> second place it must be remembered that <strong>the</strong> ossa epi<strong>pteric</strong>a,<br />
which are pl'esent at <strong>the</strong> side opposite to <strong>the</strong> frontal process, COl'respvnd<br />
<strong>in</strong> <strong>the</strong>ir extension <strong>and</strong> sitnation to this process.<br />
When we f<strong>in</strong>d a frontal process toge<strong>the</strong>r with all os epipte~<br />
ricum at <strong>the</strong> opposite side, <strong>the</strong>se two cOl'l'espoJld with <strong>the</strong> fl'ontal<br />
pl'ocess: .<br />
At last I have to mention <strong>the</strong> great val'iability <strong>in</strong> form <strong>and</strong><br />
extension of <strong>the</strong> proc. ft·ontalis. As 1 wil! expla<strong>in</strong> flll'<strong>the</strong>l' on, we<br />
can i<strong>in</strong>d tha'! <strong>in</strong> a <strong>skull</strong> with a, unilatel'al os epiptel'icum Ol' ossa<br />
epiptel'Ïca <strong>the</strong> opposite side SilOWS tbe same conditions as <strong>in</strong> a Skllll<br />
with a unilateral processns ft'outalis of <strong>the</strong> th'st type.<br />
The fl'ontal pl'ocess of <strong>the</strong> secol1l1 type, <strong>the</strong> enlargement of <strong>the</strong><br />
whole squamosal, conld be clue to two canses. In <strong>the</strong> first place we<br />
can suppose that met'ely an enlargement of <strong>the</strong> sqllamosal is cause<br />
of <strong>the</strong> exclusion of <strong>the</strong> alisphenoid from <strong>the</strong> frontal, <strong>in</strong> <strong>the</strong> sepond<br />
plaC'e we can imag<strong>in</strong>e tlmt this enhwgement is due to <strong>the</strong> opposition<br />
(v Ihe squamosal of that part of <strong>the</strong> alisphenoicl which is not<br />
41<br />
Proceed<strong>in</strong>gs Hoyal Acad. Amslerdam. Vol. XVI.<br />
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