Ulcerous Processes Or Destructive Ulcerations occur under different conditions in the arteries. They are somewhat frequent, considering the very striking integrity exhibited by the arteries in the midst of extensive abscesses. They invariably originate in the cellular sheath or its vicinity, and in no case do we meet with an ulcerous process either in or upon the inner coat of the vessel. The so-called atheromatous process, which is frequently regarded as ulceration of the inner coat of the artery, is not of an ulcerous character. To this class belong:

1. The already described suppuration of an artery (see page 95) resulting from arteritis producing purulent exudation - the suppuration arising from arteritis occurring after the application of a ligature, and which will be considered in a future page.

2. Small arterial vessels, together with the capillaries, frequently suppurate when there is suppuration of the different tissues, and we then generally find them in a state of obturation (see p. 196). In less frequent cases, a very violent suppuration of a low character affects vessels in which there is no occlusion, and occasions hemorrhage into the abscess.

3. Ulcerous destruction of the larger arteries in the form of circumscribed corrosion and perforation of the arterial wall from surrounding and contiguous abscesses, constitutes a very important and remarkable phenomenon. The wall of the artery is so much destroyed at a circumscribed spot, that it generally presents a round or oval opening, surrounded either by a smooth, as if cut, edge, or a jagged and fringed margin, and contracted in some instances towards the interior in a funnellike shape; it is attached by means of this aperture to the abscess, or to the base of the ulcer. This form of ulcerous destruction is the origin of many very dangerous external and internal hemorrhages. Among the most important of these we may instance ulcerous openings of the larger arteries in many different parts of the body. We have ourselves frequently observed perforation of the femoral artery from a suppurating syphilitic bubo, and Hasse noticed such a perforation of the vertebral artery of the right side from an ichorous abscess arising from syphilitic caries of the cervical vertebrae; and to these examples we may add the opening of different arteries on the base of perforating ulcers of the stomach, and the opening of branches of the pulmonary artery by tuberculous caverns.

These ulcerous processes, as we may sometimes notice in the ramification of the pulmonary artery in the walls of tuberculous cavities of the lungs, also give rise to a laceration of the artery. This is owing to the removal of the surrounding protecting parenchyma, and to a loosening and softening of the coats of the vessel, resulting from imbibition of the ulcerous fluid. In some cases this is preceded by a lateral dilatation of the artery towards the cavern.