452 TEE VEINS. 



Course. The anterior tibial artery, having its usual place of origin, has been 

 found to deviate outwards towards the margin of the fibula in its course along the 

 front of the leg, and then to return to its ordinary position beneath the annular 

 ligament in front of the ankle-joint. This artery has been also noticed by Pelletan 

 and by Velpeau to approach the surface at the middle of the leg, and to continue 

 downwards from that point, covered only by the fascia and integument. Yelpeau 

 states that he found the artery to reach the fore part of the leg by passing round the 

 outer side of the fibula. (Pelletan, "Clinique Chirurgicale," &c., p. 101 : Paris, 1810. 

 Velpeau, " Nouveaux Elemens de Medecine Ope"ratoire," &c., t. i., pp. 137 and 537 : 

 Paris, 1837.) 



Size. This vessel more frequently undergoes a diminution than an increase of 

 size. 



It may be defective in various degrees. Thus, the dorsal branch of the foot may 

 fail to give off digital branches to the great and second toes, which may be then 

 derived from the internal plantar division of the posterior tibial. In a farther degree 

 of diminution the anterior tibial ends in front of the ankle or at the lower part of 

 the leg ; its place being then taken by the anterior division of the peroneal artery, 

 which supplies the dorsal artery of the foot ; the two vessels (anterior tibial and 

 anterior peroneal) being either connected together or separate. 



Two cases are mentioned by Allan Burns, in which the anterior tibial artery was 

 altogether wanting, its place in the leg being supplied by perforating branches from 

 the posterior tibial artery, and on the dorsum of the foot by the anterior division of 

 the peroneal artery. 



The dorsal artery of the foot is occasionally larger than usual ; in that case com- 

 pensating for a defective condition of the plantar branch from the posterior tibial 

 artery. 



This artery has been repeatedly found to be curved outwards between its com- 

 mencement at the lower border of the annular ligament and its termination in the 

 first interosseous space. 



VEINS. 



The systemic veins commence by small branches which receive the blood 

 from the capillaries throughout the body, and unite to form fewer and 

 larger vessels, which end at last by pouring their contents into the right 

 auricle of the heart through two large venous trunks, the superior and in- 

 ferior venae cavse. The blood which nourishes the substance of the heart 

 itself, is returned by the coronary or cardiac veins to the same auricle. 



The veins, however, which bring back the blood from the stomach, 

 intestines, spleen and pancreas, have an exceptional destination ; not convey- 

 ing the blood directly to the heart, but joining to form a single trunk the 

 portal vein, which ramifies after the manner of an artery in the substance 

 of the liver, and carries the blood within it to the capillaries of that organ. 

 From these the blood passes into the ultimate twigs of the hepatic veins, 

 and is conveyed by these veins into the inferior vena cava. The veins thus 

 passing to the liver constitute the portal system. 



The anastomoses of veins are much larger and more numerous than those 

 of arteries. The veins of many parts of the body consist of a subcutaneous 

 and a deep set, which have very frequent communications with each other. 

 In some parts of the body, chiefly the limbs and surface, the veins are 

 provided with valves, whilst in others no valves exist. 



The systemic veins are naturally divisible into two groups : firstly, those 

 from which the blood is carried to the heart by the superior vena cava, viz., 

 the veins of the head and neck and upper limbs, together with those of the 

 spine and a part of the walls of the thorax and abdomen, with which may 

 be associated also the veins of the heart ; and secondly, those from which 



