ANTERIOR TIBIAL. 527 



inner side of the joint, to supply the head of the tibia and the articulation of 

 the knee. The external one passes outwards above the head of the fibula, to 

 the front of the knee-joint, lying in its course beneath the outer head of the 

 Gastrocnemius, the external lateral ligament, and the tendon of the Biceps 

 muscle, and divides into branches, which anastomose with the inferior internal 

 articular artery, the superior articular arteries, and the recurrent branch of the 

 anterior tibial. 



ANTERIOR TIBIAL ARTERY. (Fig. 300.) 



The Anterior Tibial Artery commences at the bifurcation of the popliteal, 

 at the lower border of the Popliteus muscle, passes forwards between the two 

 heads of the Tibialis Posticus, and through the aperture left between the bones 

 at the upper part of the interosseous membrane, to the deep part of the front 

 of the leg ; it then descends on the anterior surface of the interosseous liga- 

 ment, and of the tibia, to the front of the ankle-joint, where it lies more super- 

 ficially, and becomes the dorsalis pedis. A line drawn from the inner side of 

 the head of the fibula to midway between the two malleoli will mark the course 

 of the artery. x 



Relations. In the upper two-thirds of its extent, it rests upon the interosseous 

 ligament, to which it is connected by delicate fibrous arches thrown across it. 

 In the lower third, upon the front of the tibia, and the anterior ligament of the 

 ankle-joint. In the upper third of its course, it lies between the Tibialis Anti- 

 cus and Extensor Longus Digitorum; in the middle third, between the Tibialis 

 Anticus and Extensor Proprius Pollicis. In the lower third it is crossed by the 

 tendon of the Extensor Proprius Pollicis, and lies between it and the innermost 

 tendon of the Extensor Longus Digitorum. It is covered, in the upper two- 

 thirds of its course, by the muscles which lie on either side of it, and by the 

 deep fascia; in the lower third, by the integument, annular ligament, and fascia. 



The anterior tibial artery is accompanied by two veins (venas comites), which 

 lie one on either side of the artery ; the anterior tibial nerve lies at first to its 

 outer side, and about the middle of the leg is placed superficial to it ; at the 

 lower part of the artery the nerve is generally again on the outer side. 



PLAN OF THE RELATIONS OF THE ANTERIOR TIBIAL ARTERY. 



In front. 



Integument, superficial and deep fasciae. 

 Tibialis Anticus (overlaps it in upper part of leg). 

 Extensor Longus Digitorum ) / , .. ,- r Al \ 

 Extensor Proprius Pollicis } ( OVerla P Xt sll ht W- 

 Anterior tibial nerve. 



In*ner side. /^ ^N. Outer side. 



Tibialis Anticus / \ Anterior tibial nerve. 



Extensor Proprius Pollicis ( ^5 t ^. li r j Extensor Longus Digitorum. 



(crosses it at its lower \ lia ' j Extensor Proprius Pollicis. 



part). V / 



Behind. 



Interosseous membrane. 

 Tibia. 

 Anterior ligament of ankle-joint. 



Peculiarities in Size. This vessel may be diminished in size, may be deficient to a greater or 

 less extent, or may be entirely wanting, its place being supplied by perforating branches from 

 the posterior tibial, or by the anterior division of the peroneal artery. 



Course. The artery occasionally deviates in its course towards the fibular side of the leg, 

 regaining its usual position beneath the annular ligament at the front of the ankle. In two 

 instances, the vessel has been found to approach the surface in the middle of the leg, being 

 covered merely by the integument and fascia below that point. 



Surgical Anatomy. The anterior tibial artery may be tied in the upper or lower part of the 

 leg. In the upper part, the operation is attended with great difficulty, on account of the depth 



