Fig. 181
Surgical anatomy and ligation of the anterior tibial and peroneal arteries. (Bernard and Huette.)
The Anterior Tibial Artery.
—The anterior tibial artery underlies a line drawn from a point between the head of the fibula and the outer tuberosity of the tibia, to the front and centre of the ankle-joint. At almost any point along this line it can be exposed between the tibialis anticus and the common extensor of the toes, the latter being held downward and outward and the former upward. Here in the depths it may be recognized upon the interosseous membrane. In the lower part of the leg the extensor pollicis lies to its outer side. Here the accompanying veins should be avoided. Quite low in the leg and in front of the ankle the vessel will be found between the tendons of the tibialis anticus and extensor pollicis ([Figs. 180] and [181]).
THE VEINS.
The veins are of interest to the surgeon particularly because of the role they play in the pathology of sepsis, especially of pyemia, and because of their various dilatations and even new formations which admit of none but surgical remedy; that is, varices, under their various names—for example, hemorrhoids, varicocele, and nevi.
The veins have an endothelial lining, between which and circulating, or more especially stagnant, blood there exist peculiar susceptibilities and relations which cannot be well described. The pathologist appreciates what disturbances of the endothelium will provoke coagulation of the blood in contact with it, but is not yet in a position to explain the relationship. Veins, moreover, are provided with valves to a more perfect degree than are the lymphatics, but the valves often become inadequate for their purpose, and then we have such conditions as varicosities; the fact that they are usually seen about the rectum and the lower extremities illustrating the disadvantages accruing from the upright position into which, by the process of evolution, man has erected himself from the quadrupedal. Even the myriads of years that have elapsed since this change took place have not sufficed to afford sufficient protection against the added weight of the column of blood inseparable from it.
Of pathological changes which interest the surgeon there may be atrophy as the result of pressure from without or prolonged distention from within, even to such an extent as to permit of rupture and serious or fatal hemorrhage. Fatty degeneration occurs in the serious intoxications and infections. Calcification occurs only in limited areas and is secondary to other changes or to thrombophlebitis. True osseous patches have been found in the walls of veins, but are great rarities. Calcification occurs in the portal and also in the femoral veins and their branches. In other directions vein walls become hypertrophied, all coats partaking in the change, enlargement or distention being especially likely to occur where there is most tendency to stagnation. The changes which lead to the varicose condition include not only absolute thickening, but increase in every dimension, the venous tubes becoming elongated as well as distended and thickened, to such an extent that they take a spiral or curved course, sometimes almost doubling on themselves.