A text-book of the diseases of the ear and adjacent organs . 50 temporal bones examined by him in only 86*8 per cent, did the mastoidprocess contain pneumatic spaces alone. In 432 per cent, it was partiallydiploetic, and partially pneumatic, and in 20 per cent, it was entirely or sclerosed. We therefore differentiate three principal types of the mastoid process : thepneumatic, the diploetic, and the combination of the two or mixed form. Thepneumatic mastoid process is often composed of a large number of irregularcellular spaces, penetrating the temporal bone in all directions a
A text-book of the diseases of the ear and adjacent organs . 50 temporal bones examined by him in only 86*8 per cent, did the mastoidprocess contain pneumatic spaces alone. In 432 per cent, it was partiallydiploetic, and partially pneumatic, and in 20 per cent, it was entirely or sclerosed. We therefore differentiate three principal types of the mastoid process : thepneumatic, the diploetic, and the combination of the two or mixed form. Thepneumatic mastoid process is often composed of a large number of irregularcellular spaces, penetrating the temporal bone in all directions and coveredby a thin external osseous lamella (Fig. 46). In other cases the whole processconsists of one or two large cavities, or of numerous small cavities, together TOPOGEAPHY OF THE MASTOID PROCESS. 47 with one or more larger ones, which, either at the apex or inner side, givea dome-shape to the roof. Frequently large cavities communicate with theantrum by a narrow canal only. A satisfactory idea of the position of the mastoid cells in the temporal bone. Fig. 47.—Corrosion Cast of the Middle Ear (after Bezold). Osteum pharyng. tubae ; i, Isthmus tubae ; ot, Osteum tymp. tubae ; u, Lowerportion of the cavum tyrapani ; t, Membrana tympani with the depression for themalleus and umbo ; h, Cavity for the malleus and incus ; a, Posterior end of themastoid antrum ; e, Intercellular space ; te, Terminal space. can only be obtained by means of corrosion preparations. The same remarkapplies to the topography of the organ of hearing. On this subject we aregreatly indebted to Fried. Bezold, whose masterly work, Die Corrosions-anatomie des Ohres, Munchen, 1882, cannot be too highly recommended. The pneumatic cellular cavities starting from the mastoid antrum extendbackwards to the sutura occipitalis, surrounding the transverse sinus and theemissarium santorin; downwards to the apex and inner surface of the mastoid process; upwards and forwardsto the linea temporalis and the root of the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecteardiseases, bookyear
