. The anatomy and physiology of the human body. Containing the anatomy of the bones, muscles, and joints; and the heart and arteries. of the largerones, and the veins of the lower extremity much thicker andstronger than in the upper parts of the body, as they have to beara higher column of blood. The veins are transparent and theblood is seen through their coats. The veins have three outer coat is composed of a reticulated tissue of cellularmembrane, which is wrapped somewhat loosely around theproper coats. The second coat or proper coat has the samecharacter of an interwoven texture
. The anatomy and physiology of the human body. Containing the anatomy of the bones, muscles, and joints; and the heart and arteries. of the largerones, and the veins of the lower extremity much thicker andstronger than in the upper parts of the body, as they have to beara higher column of blood. The veins are transparent and theblood is seen through their coats. The veins have three outer coat is composed of a reticulated tissue of cellularmembrane, which is wrapped somewhat loosely around theproper coats. The second coat or proper coat has the samecharacter of an interwoven texture of filaments ; but it is moredense, especially on its internal surface, where it approachesthe inner, coat. The inner coat is dense and unelastic, resem-bling the inner coat of the artery, but stronger, more pliant,and less easily ruptured by ligature. Betwixt all the coatsthere is a fine cellular substance interposed.* The inner coatboing smooth and flexible is formed into valves in various partsof the veins ; which valves are semi-lunar, and resemble thosein the root of the great arteries in the heart. Vein inverted. Valve. In all the larger veins, excepting those of the viscera, of the * Unless near the auricle no musciiJar fibres have been observed. See SaUerlOpen .Minora, p. 175. 230 OF THE VEINS abdomen, and those of the lungs and brain, there are valves;but in the smaller veins there are no valves ; these valves, as Ihave said, consist of the inner coat, forming iolds like a curtain,hung across the calibre of the vein; but at the same time at-tached so obliquely to the side of the vein, that they present asacculated membrane to receive the refluent blood. The loosemargin of the valve is somewhat stronger than the other part,and betwixt the duplicature some little filaments may be ob-served. Each valve consists, in general, of two semi-lunarmembranes, the margins of which, falling together, preventthe blood from passing retrograde ; but they yield and givefreedo
Size: 2331px × 1072px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecad, booksubjecthumananatomy, bookyear1822
