The development of the human body; a manual of human embryology . uced by thehollowing and bulging out of a portion of the petrous bone by outgrowths from the lin-ing membrane of the middleear. The cavities so formedare the mastoid cells, andtheir relations to the middle-ear cavity are in all respectssimilar to those of the eth-moidal and sphenoidal cells tothe nasal cavities. The re-maining portions of the tem-poral bone are partly formedby membrane bone andpartly from the branchialarch skeleton. An ossificationappears in the membranewhich forms the side of theskull in the temporal region and
The development of the human body; a manual of human embryology . uced by thehollowing and bulging out of a portion of the petrous bone by outgrowths from the lin-ing membrane of the middleear. The cavities so formedare the mastoid cells, andtheir relations to the middle-ear cavity are in all respectssimilar to those of the eth-moidal and sphenoidal cells tothe nasal cavities. The re-maining portions of the tem-poral bone are partly formedby membrane bone andpartly from the branchialarch skeleton. An ossificationappears in the membranewhich forms the side of theskull in the temporal region and gives rise to a squamosalbone (s), which later unites with the petrous to form thesquamosal portion of the adult temporal, and anothermembrane bone, the tympanic (t), develops from a centerappearing in the mesenchyme surrounding the externalauditory meatus, and later also fuses with the petrous toform the floor and sides of the external meatus, givingattachment at its inner, edge to the tympanic , the styloid process is developed from the upper. Fig. 104.—The Temporal Boneat Birth. The StyloidProcess and Auditory Os-sicles are not Repre-sented. p, Petrous bone; s, squamosal;t, tympanic.—(Poirier.) THE SKULL. 20I part of the second branchial arch, whose history will beconsidered later. The various ossifications which form in the chondro-cranium and the portions of the adult skull which repre-sent them are shown in the following table: Region ofChondrocranium. Ossifications. Occipital, Sphenoidal, Ethmoidal, {BasioccipitalExoccipitalsSupraoccipital Basisphenoid 1Presphenoid J-Lingular j Alisphenoids . Orbitosphenoids Mesethmoid Ectethmoids Inferior turbinated. Sphenoidal turbinated Periotic capsule, Parts of Adult Skull. Basilar Squamous portion above su-perior nuchal line. Body. Greater wings and externalpterygoid plates. Lesser wings,f Lamina Crista galli.(Nasal septum.(Lateral masses,-j Superior turbinated.(Middle turbi
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
