Carpenter's principles of human physiology . oportionate to that of theblood corpuscles, being large in reptiles and fish, and smaller in the higherclasses of vertebrata. In man their Jong diameter is about l-1800th of aninch, and their short 1-6000th of an inch. Every lacuna is occupied in theliving bone by a mass of protoplasm which sends prolongations into thecanaliculi, and is the nutritive centre of the surrounding osseous , instead of a thin lamella of bone, sections of one of the long bones beexamined, it will be found that the penetration of the tissue by bloodvesselsrender
Carpenter's principles of human physiology . oportionate to that of theblood corpuscles, being large in reptiles and fish, and smaller in the higherclasses of vertebrata. In man their Jong diameter is about l-1800th of aninch, and their short 1-6000th of an inch. Every lacuna is occupied in theliving bone by a mass of protoplasm which sends prolongations into thecanaliculi, and is the nutritive centre of the surrounding osseous , instead of a thin lamella of bone, sections of one of the long bones beexamined, it will be found that the penetration of the tissue by bloodvesselsrenders a peculiar arrangement of the lacunae and canaliculi requisite. Thesolid osseous texture which forms the shaft is covered by a strong and firmlayer of connective tissue termed the periosteum, in which numerous blood-vessels ramify, and is lined by a very thin and delicate layer of the same tissue, * See Meyer, Die Architectur der Spongiosa, Reichert and Dubois-Reymonds Archiv.,I867 ; Wolff and Culmann, Die Graphische Statik. Zurich, 48 CONNECTIVE TISSUES—BONE. Fig. 36. to which the term endosteum is applied. This also is freely supplied withsmall vessels derived from the nutrient artery or arteries of the bone. Fromboth the external and internal membranes numerous small bloodvesselspenetrate the bone, occupying a series of canals that were first described byClopton Havers, and have been named after him theHaversian canals. These, for the most part, runparallel to the central cavity, communicating, how-ever, with one another by frequent transversebranches, so that the whole system forms an irregularnetwork, and pervades every part of the solid tex-ture (Fig. 36). The diameter of the Haversiancanals varies from 1-2500th to l-200th of an inch ormore; their average diameter may be stated at aboutl-500th of an inch. The Arteries and Veins usuallyoccupy separate channels, and those enclosing thelatter are, in some instances, as in the diplbe of theflat bones of the skull,
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectphysiology, bookyear1
