On pteric sutures and pteric bones in the human skull - DWC - KNAW

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636 figlll'e 1 by a clotted line, it lOt\el!cs tbe parietal (vide figure f). This is GIWBER'S "mittelbal'e Verbindllng". Type H shows aregutal' enlargement of the whole squamosal in the direction of the-fl'ontal, so, that a fronto-temporal sllture is for121ed. This is GIWBEU'S "1l111nittelbare Vel'bindllng". J .illnction of the serond type ('an be combinecl with a fronta1 process of the th'st type. The number of examined skulls is 114; Ü\ 47 1 fOlll\d a frol\t9- temporal suture i. e. in 41,14 %' The skllih. of tbe lwo dIifel'Ant klJlds are divided as follows. In 34 cases we have a frolltal pl'ocess of the th'st tJ pe._ In 13 cases the two sides of the &kllil are s,vmmetl'ical. In 21 the fi'onLal pl'ocess is onl)' pL'osent at olle side. 5 of the 13 simlis with eymme· tl'ical fl'ontal pl'ocess show a combination of tlw fil'st and the second type, so that fl'om tbe fiJ'st' type 8 are fOllnd with the fl'ontal process on both sides, to 21 witll the front. proc. on one side; which Lllcans that the unilateral pl'esence is mllch 11101'e fl'equen t than the bilatel'al. In 13 skulls the serond type ,,.,as fOllnd. Of 110 less than 12 skull& the two sides were symmetria.l anel ün1y ollce I fOllIlcl a llnilatel'al enlargement of tlJe s'luamosal, which proves that 1 he bilateml pl'esence is ffillCli more frequent thall the llnilatel'al. In the unilatel'al pl'esence of a frontal process of the fiL'st. type I fOllnd ihis process 13 times on the left sicle of the skull against 6 times on lhe l'ight one j so the left half of tile skull sl1l'passes stl'ongly the l'ight one in tbis respect. An investigntion of the ptel'ic l'egion of tbe side of the skull opposite to a frontal pt'ocess of the fil'&t type led to the following facIs: 1. Pl'ocessus frontaJis at the 1eft side. A spheno-pal'ietal sutUl'e at tbe l'ight sicle in 6 skulls. An os epiptel'icum typicum " " " " 3 " Several ossa epiptel'ica ,. " " " " 1 skull. A tempol'al pl'Oc. at tbe fl'ontal " " " " 1 " Il, Pl'OCe&SllS fl'ontalis + os epiptericum at the left side. An os epiptel'icum-typicum at the l'i~ht side in 2 sknlls. IJ Pl'ocessus fl'ontalis at tbe l'iglIt side. A spheno-pal'ietal sllture at the left side in 2 skulls. Au os epiptericulU typicum" " " " ,,2 " Sevêral ossa epiptel'ictl, "" " " " 2 A spheno-parietal sllture is mostly fOllncl at the sicle opposite to the fL'ontal pl'ocess '(in 8 of 19 cases). This sutUl'e is not always situatecl in the same place. U sually iL lies at the level of the su tura j - 4 -
637 sqnamosa, 80 that the l'egion of the fl'ontal process is inc1uded in the alisphenoïd. Sometimes the spheno-parieta1 sutUl'e lies at the le\'el of the 10we1' border of the frontal process; so that the region of this process is iocl uded in the parietaJ. Tbe region of tbe frontal pl'ocess of Olle side cao be incillded in the frontal, as is pl'oved by a skull, which pJ'esents at the 1eft side a ti'ontal procesfl of the tempo ral and at the right side a symmetrical temporal process of the frontal. If at the side opposite to the frontal process one Ol' more ossa epiptel'ica are found, the situation cand extension of these bones are equal Jo those of the ti'ontal process. We find other relations in the skulls with frontal proces sus of the second type. Here the enlal'gemeu't of the squamosal is nearly always absolutely sJ mmetrical. Only once did I find a second type of fl'ontal procees at one side and an ós epiptericum typicum at the othel' one. I suppose th at the question aftel' genesis and significance of the above mentioned two (ypes of ti'ontal processus must be answel'ed as follows. The proc. fi'ontalis of the first type is to be considereà as the homologon of an os epiptel'icUlll typicum. Following arguments led me to this opinion. In the fil'st place it is possible that the l'egion of a unilatel'al proc. - frontalis can be included at the opposite side in one of the surl'ounding bon es (sphenoid, f1' on tal, parietai), In the second place it must be remembered that the ossa epipterica, which are pl'esent at the side opposite to the frontal process, COl'respvnd in their extension and sitnation to this process. When we find a frontal process together with all os epipte~ ricum at the opposite side, these two cOl'l'espoJld with the fl'ontal pl'ocess: . At last I have to mention the great val'iability in form and extension of the proc. ft·ontalis. As 1 wil! explain flll'thel' on, we can iind tha'! in a skull with a, unilatel'al os epiptel'icum Ol' ossa epiptel'Ïca the opposite side SilOWS tbe same conditions as in a Skllll with a unilateral processns ft'outalis of the th'st type. The fl'ontal pl'ocess of the secol1l1 type, the enlargement of the whole squamosal, conld be clue to two canses. In the first place we can suppose that met'ely an enlargement of the sqllamosal is cause of the exclusion of the alisphenoid from the frontal, in the sepond plaC'e we can imagine tlmt this enhwgement is due to the opposition (v Ihe squamosal of that part of the alisphenoicl which is not 41 Proceedings Hoyal Acad. Amslerdam. Vol. XVI. - 5 -
Page 1 and 2: Huygens Institute - Royal Netherlan
Page 3: 635 Au examination of tlle Sklllls
Page 7: 639 epÎptel'iCllm typicllm can sho

On pteric sutures and pteric bones in the human skull - DWC - KNAW

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