A system of human anatomy, general and special . the tooth alltrace of the parietes or mode of connexionof the cells is lost, but after steeping in weakacid the cellular network is perfectly distinct. The enamel forms a crust over the whole exposed surface of thecrown of the tooth to the commencement of its root; it is thickestover the upper part of the crown, and becomes gradually thinner as itapproaches the neck. It is composed of minute hexagonal crystallinefibres, resting by one extremity against the surface of the ivory, and * See an excellent practical work, On the Structure, Economy, an
A system of human anatomy, general and special . the tooth alltrace of the parietes or mode of connexionof the cells is lost, but after steeping in weakacid the cellular network is perfectly distinct. The enamel forms a crust over the whole exposed surface of thecrown of the tooth to the commencement of its root; it is thickestover the upper part of the crown, and becomes gradually thinner as itapproaches the neck. It is composed of minute hexagonal crystallinefibres, resting by one extremity against the surface of the ivory, and * See an excellent practical work, On the Structure, Economy, and Pathology of theTeeth, by Mr. Lintott. t Microscopic section of a molar tooth. 1. Enamel with its columns and laminatedstructure. 2. Cortical substance or cementum on the outside of the fang. 3. Ivory,showing tubuli. 4. Foramen entering- the dental cavity from the end of the fang. Thisfang has a bulbous enlargement in consequence of a hypertrophy of the Dental cavity. 6. A few osseous corpuscles in the ivory just under the DEVELOPEMENT OF TEETH. 101 constituting by the other the free surface of the crown. The fibresexamined on the face of a longitudinal section have a waving arrange-ment, and consist, like those of ivory, of cells connected by their sur-faces and ends and filled with calcareous substance. When the latteris removed by weak acid, the enamel presents a delicate cellular net-work of animal matter. The cortical substance, or cementum, (substantia ostoidea,) forms athin coating over the root of the tooth, from the termination of theenamel to the opening in the apex of the fang. In structure it isanalogous to bone, and is characterized by the presence of numerouscalcigerous cells and tubuli. The cementum increases in thicknesswith the advance of age, and gives rise to those exostosed appear-ances occasionally seen in the teeth of very old persons, or in thosewho have taken much mercury. In old age the cavitas pulpas is oftenfound filled up and o
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectanatomy, bookyear1847
