ANTERIOR TIBIAL VESSELS. 631 



tibialis anticus and the extensor longus digitorum ; afterwards it is placed 

 between the tibial muscle and the extensor proprius pollicis till near the 

 lower end, where the last muscle becomes superficial, and crosses to the 

 inner side. The vessel rests on the interosseous membrane in two-thirds 

 of its extent, being overlapped by the fleshy bellies of the contiguous 

 muscles, so that it is at some depth from the surface ; but it is placed in 

 front of the tibia and the ankle joint in the lower third, and is compara- 

 tively superficial between the tendons of the muscles. 



Venae comites entwine around the artery, covering it very closely with 

 cross branches on the upper part. The anterior tibial nerve approaches 

 the tibial vessels about the middle third of the leg, and continues with them, 

 crossing once or twice : at the lower end of the artery the nerve lies on 

 the outer side. 



Branches. In the leg the anterior tibial artery furnishes mostly mus- 

 cular offsets, but near the knee and ankle the following named branches 

 take origin. 



a. Cutaneous branches arise at intervals ; and the largest accompanies 

 the musculo-cutaneous nerve, and supplies the contiguous muscles. 



b. A recurrent branch arises as soon as the trunk appears above the 

 interosseous membrane, and ascends in the tibialis anticus to the knee 

 joint : on the joint it anastomoses with the other articular arteries. 



c. Malleolar arteries (internal and external) spring near the ankle joint, 

 and are distributed over the ends of the tibia and fibula. The internal is 

 the least regular in size and origin ; the external anastomoses with the 

 anterior peroneal artery. 



d. Some small articular branches are supplied from the lower end of 

 the artery to the ankle joint. 



The DORSAL ARTERY of the foot is the continuation of the anterior tibial, 

 and extends from the front of the ankle joint to the posterior part of the 

 first interosseous space : at this interval it passes downwards between the 

 heads of the interosseous muscle, to end in the sole (p. 624). 



The artery is supported by the inner row of the tarsus, viz., the astra- 

 galus, and the scaphoid and cuneiform bones ; and it is covered by the 

 integuments and the deep fascia, and by the inner piece of the extensor 

 brevis muscle. The tendon of the extensor pollicis lies on the inner side, 

 and that of the extensor longus digitorum on the outer side, but neither is 

 near the vessel. 



The veins have the same position with respect to the artery as in the 

 leg ; and the nerve is external to it. 



Peculiarities. On the dorsum of the foot the artery is often removed further 

 outwards than the line from the centre of the ankle to the posterior part of the 

 first interosseous space. Further, the place of the artery may be taken by a large 

 anterior peroneal branch . 



Branches. Offsets are given to the bones and ligaments of the foot : 

 those from the outer side of the vessel are named tarsal and metatarsal 

 from their distribution. A small interosseous brancli is furnished to the 

 first metatarsal space. 



a. The tarsal branch arises opposite the scaphoid bone, and runs be- 

 neath the extensor brevis digitorum to the outer side of the foot, where it 

 divides into twigs that inosculate with the metatarsal, plantar, and ante- 

 rior peroneal arteries : it supplies offsets to the extensor muscle beneath 

 which it lies. 



