. Cunningham's Text-book of anatomy. Anatomy. 142 OSTEOLOGY. Perpen licular plate Crista «alli Slitfornaso-ciliary. Lamina papyracea Ethmoidal labyrinth nects the ethmoidal labyrinths with the perpendicular plate. It occupies the interval between the orbital parts of the frontal bone, roofing in the nasal cavities interiorly, and superiorly forming on either side of the crista galli two shallow olfactory grooves in which, in the recent con- dition, the olfactory lobes of the cerebrum are lodged. Numerous foramina for the trans- mission of the olfactory nerves pierce this part of the bone; thos
. Cunningham's Text-book of anatomy. Anatomy. 142 OSTEOLOGY. Perpen licular plate Crista «alli Slitfornaso-ciliary. Lamina papyracea Ethmoidal labyrinth nects the ethmoidal labyrinths with the perpendicular plate. It occupies the interval between the orbital parts of the frontal bone, roofing in the nasal cavities interiorly, and superiorly forming on either side of the crista galli two shallow olfactory grooves in which, in the recent con- dition, the olfactory lobes of the cerebrum are lodged. Numerous foramina for the trans- mission of the olfactory nerves pierce this part of the bone; those to the medial and lateral sides of the groove are the largest and most regular in their arrangement. Along the lateral edges of the cribriform plate two notches can usually be distinguished; when articulated with the frontal bone these form the medial openings of the ethmoidal foramina. Leading forwards from the anterior of these there is often a groove which crosses to the side of the crista galli, where it ends in a slit which allows of the transmission of the naso-ciliary nerve to the nose. Posteri- orly the cribriform plate articulates with the spine of the sphenoid. Connexions.—The ethmoid articulates with the sphenoid and sphenoidal conchas, the frontal, the two nasals, two maxillae, two lacrimals, two inferior conchas, two palates, and the vomer. Ossification takes place in the cartilage of the nasal capsule. Each lateral mass has one centre, which appears about the fourth or fifth month in the neighbourhood of the lamina papyracea. According to Fawcett ossification first commences in a process which passes outside the naso-lacrimal duct to reach the frontal process of the maxilla. From this the lamina? around the ethmoidal air-cells are formed, which are complete at birth, the air-sinuses in this instance not being formed by the absorption of cancellous bone. From these centres the conchee are also developed, and these too are ossified at the ninth month. At birth
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
