. Principles of human physiology : with their chief applications to pathology, hygiene, and forensic medicine : especially designed for the use of students. riosteal layer, preserve their relation to the vascular surface to whichthey pertain, and face inwards towards the vessel. Wherever the vesselpenetrates, whatever direction it takes, and however it branches, it is every-where accompanied by this sheath from the periosteal layer, or by offsetsfrom it; and, when it enters the medullary canal, its sheath expands intothe medullary layer. The vessels of the compact tissue are so close together
. Principles of human physiology : with their chief applications to pathology, hygiene, and forensic medicine : especially designed for the use of students. riosteal layer, preserve their relation to the vascular surface to whichthey pertain, and face inwards towards the vessel. Wherever the vesselpenetrates, whatever direction it takes, and however it branches, it is every-where accompanied by this sheath from the periosteal layer, or by offsetsfrom it; and, when it enters the medullary canal, its sheath expands intothe medullary layer. The vessels of the compact tissue are so close together that the osseoussheaths respectively surrounding them come into contact and unite; and thusall the space between the outer and the inner surface of the compact tissueis filled up; thus, in a word, the compact tissue is constructed. As the vessels of the compact tissue take a longitudinal direction, a trans-verse section of the bone will appear pierced by numerous holes, which arethe Haversian canals cut across. Each hole appears as the centre of aroundish area, which is the section of an involuted periosteal layer now be FORMATION OF THE TISSUES. 467. Transverse section of thecompact tissue of a longbone; showing, a. The pe-riosteal layer. 6. The me-dullary layer, and the in-termediate Haversian sys-tems of lamellae, each per-forated by an H. canal.—Magnified about 15 diame-ters. come a vertical rod, containing a vessel in its axis. The Haversian canals vary considerably in size, and do not maintain a very close relation to the thickness of their respect- Fig. 55, e. ive osseous walls. They are frequently eccentric, a owing to their wall bulging more in one direction than another, to fit in between others in the vicinity: for though the rods of bone, containing the vessels, affect the cylindrical form, they often present an oval, or even a very irregular figure, on a section; their close package having modified their form. The periosteal and medullary layers are also well see
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Keywords: ., bookcentury1800, bookdecade1840, bookpubli, booksubjectphysiology
