448 ANTERIOR TIBIAL ARTERY. 



B. From the plantar arch are given off the following more important 

 branches. 



(a) The posterior perforating branches, three in number, pass upwards 

 through the back part of the three outer interosseous spaces, between the 

 heads of the dorsal interosseous muscles, and on reaching the dorsum of the 

 foot inosculate with the interosseous branches of the metatarsal artery. 



(6) The digital branches are four in number. The first digital branch 

 inclines outwards from the outermost part of the plantar arch, opposite the 

 end of the fourth metatarsal space, crosses under cover of the abductor 

 minimi digiti, and runs along the outer border of the phalanges of the little 

 toe. The second digital branch passes forwards along the fourth metatarsal 

 space, and near the cleft between the fourth and fifth toes divides into two 

 vessels, which course along the contiguous borders of those toes, and end on 

 the last phalanges. The third digital branch is similarly disposed of on the 

 fourth and third toes. The fourth ends in like manner on the third and 

 second toes. 



The digital artery which supplies the opposed sides of the first and second 

 toes, and that which runs on the inner side of the first toe, arise deeply 

 between the first and second metatarsal bones, usually from that part of the 

 arch which is formed by the end of the dorsal artery of the foot. 



Thus, as in the fingers, collateral arteries pass along the sides of the flexor 

 surface of each of the toes. Near the base of the last phalanx these 

 inosculate so as to form an arch, from the convexity of which minute vessels 

 pass forwards to the extremity of the toe, and to the matrix of the nail. 



An anterior perforating branch is sent upwards by each of the digital arteries of the 

 three outer interspaces near its bifurcation, to communicate with the corresponding 

 digital branch of the metatarsal artery of the dorsum of the foot. 



PECULIARITIES. The posterior perforating branches, which are usually very small 

 vessels, are sometimes enlarged, and furnish the interosseous arteries on the upper 

 surface of the foot ; the metatarsal branch of the dorsal artery, from which the inter- 

 osseous arteries are usually derived, being in that case very small. 



ANTERIOR TIBIAL ARTERY. 



The anterior tibial artery, placed along the fore part of the leg, is at first 

 deeply seated, but gradually approaches nearer to the surface as it descends. 

 It extends from the division of the popliteal artery to the bend of the 

 ankle ; whence it is afterwards prolonged to the interval between the first 

 and second metatarsal bones, under the name of dorsal artery of the foot. 



The anterior tibial artery is at first directed forwards to reach the anterior 

 surface of the interosseous ligament, passing through the divided upper end 

 of the tibialis posticus, and through the interval left unoccupied by the in- 

 terosseous ligament. It then extends obliquely downwards to the middle of 

 the ankle-joint, in a direction which may be nearly indicated by a line 

 drawn from the inner side of the head of the fibula to midway between the 

 two malleoli. Lying with the tibialis anticus on its inner side, and having 

 the extensor communis digitorum and, lower down, the extensor proprius 

 pollicis on its outer side, the vessel is deeply placed at the upper part of 

 the leg, where those muscles are fleshy ; but it is comparatively superficial 

 below, between their tendons, and comes forward upon the tibia. At the 

 bend of the ankle it is covered by the annular ligament, and is crossed from 

 without inwards by the tendon of the extensor proprius pollicis. In its 



