This section is from the book "A Manual Of Pathological Anatomy", by Carl Rokitansky, William Edward Swaine. Also available from Amazon: A Manual of Pathological Anatomy.
We have already noticed, under the head of Anomalies of the Heart, the most important anomalies and other deficiencies of structure affecting the trunks of the venous system. Moreover our remarks, in the corresponding chapter on the Arteries, apply likewise to the Veins.
Various anomalies of this nature are of frequent occurrence in the venous system, although they do not, according to Meckel, preponderate over those of the arteries to so extensive a degree as is generally supposed. We refer our readers to the more circumstantial anatomical works for a detailed notice of these anomalies.
There is, however, one form of anomaly belonging to this class which deserves especial mention, notwithstanding the notice which will be given of it under Dilatations of the Veins. This form consists in an anastomosis of the epigastric cutaneous veins with the umbilical vein at the navel, on which depend the persistence and patency of the latter vessel.
We purpose, for the better comprehension of the subject, prefacing our consideration of other anomalies, as, for instance, those of calibre, by a notice of these diseases.
The study of inflammation of the veins (Phlebitis) constitutes one of the most important departments of pathology. It is entirely the result of anatomical research; yet, however complete may appear to be the development which this subject has attained in our day, it still presents many important deficiencies, which have either been disregarded by observers designedly or from a deficiency of materials, or have been supplied by irrational conclusions and hypotheses.
Inflammation of the veins is a very frequent disease, and is highly important, both on its own account, and also more especially from the absorption of its products into the blood. It is, under all circumstances, incomparably more frequent than inflammation of the arteries.
Its seat is the cellular coat of the vein, and likewise the cellular fibrous coat, in as far as the latter exhibits a certain degree of vascularity; and its products are deposited alike in the tissue of both these coats, and in the non-vascular strata of the lining membrane of the vessel from whence they extend to the canal of the vein.
It more frequently exhibits an acute than a chronic character, and it is then distinguished by the deposition of exudation on the inner surface of the vessel. The following remarks refer to this form of the disease, the chronic form of which will be considered in a future page.
It is especially necessary to distinguish two forms of phlebitis:
 
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