The dorsal artery of the foot (a. dorsalis pedis), the continuation of the anterior tibial artery, extends from the termination of that vessel at the bend of the ankle, to the posterior end of the first metatarsal space, where it divides into two branches, of which one proceeds forwards in the first interosseous space, whilst the other dips into the sole of the foot, and terminates by inosculating with the plantar arch. This vessel, in its course forwards, rests upon the astragalus, the scaphoid, and internal cuneiform bones and their respective articulations. It lies in the interval between the tendon of the proper extensor of the great toe, and that of the long extensor of the other toes ; and is covered by (besides the integument) the fascia of the foot, and by a layer of dense cellular membrane, which binds it to the parts beneath. Near its end, it is crossed by the innermost tendon of the short extensor of the toes.
Two veins accompany this artery; the anterior tibial nerve lies beneath it and on its outer side.
The principal branches of the dorsal artery of the foot are directed outwards and forwards upon the tarsus and metatarsus, and are named accordingly. Some small offsets also run obliquely inwards, and ramify upon the inner side of the foot.
The tarsal branch, [tarsea,] M arises from the artery usually where it crosses the scaphoid bone, but its point of origin varies in different instances. It inclines forwards and outwards upon the tarsal bones covered by the short extensor muscle of the toes, to which, and to the tarsal articulations, it gives small vessels. The tarsal artery, then curving backwards towards the cuboid bone, divides into branches which take different directions : some of them run forwards, to anastomose with the divisions of the metatarsal artery; others outwards, to communicate at the outer border of the foot with branches of the external plantar artery; whilst a third set anastomoses with branches of the external malleolar, and with those of the peroneal artery upon the outside of the calcaneum.
The metatarsal branch, [metatarsea,] arises farther forward than the preceding vessel, but, like it, is directed outwards beneath the short extensor muscle. Sometimes there are two metatarsal arteries, the second being of smaller size ; and not infrequently, when there is but a single vessel of this name, it arises in common with the tarsal artery. Its direction is necessarily influenced by these circumstances; being oblique when it arises far back, and almost transverse when its origin is situated farther forwards than usual. Branches pass off in different directions for the supply of the surrounding structures ; some of these run outwards and anastomose with offsets from the external plantar artery, whilst others curve backwards, to join with those of the tarsal artery. The interosseous branches only require to be specially noticed :
The interosseous arteries, [a. interossese,] three in number, are so named from their position between the metatarsal bones. They are small straight vessels which pass forwards along the three outer interosseous spaces, resting upon the dorsal interosseous muscles. Somewhat behind the clefts between the toes each interosseous artery divides into two branches, which run forward along the contiguous borders of the corresponding toes, forming their dorsal collateral branches.
Moreover, from the outermost of these interosseous arteries a small branch is given off, which gains the outer border of the little toe, and forms its external collateral branch. Hence it appears, that the interosseous branches derived from the metatarsal artery supply the dorsal surface of the three outer toes, and that of one side of the second toe.
As these vessels bifurcate opposite the fore part of the interosseous spaces, they communicate with the plantar artery by means of the anterior perforating branches ; and at the back part of the interosseous spaces, they are likewise joined by the posterior perforating branches of the same artery.
First interosseous branch (dorsal artery of the great toe : dorsalis pollicis). — When the dorsal arteiy of the foot has reached the first metatarsal space, it gives off this branch, which runs along the outer surface of the first metatarsal bone, and is analogous to the other interosseous arteries. On reaching the fissure between the first and the second toes this branch divides into two smaller vessels, which run along the contiguous borders of these two toes on their dorsal surface.
After having furnished this branch, the dorsal artery of the foot dips into the first interosseous space between the heads of the first dorsal interosseous muscle, and inosculates with the end of the external plantar artery, so as to complete the plantar arch.
At this point it gives off two branches. One of these crosses beneath the first metatarsal bone, and runs along the inner side of the great toe on its plantar surface ; the other is directed forwards opposite the first metatarsal space, and divides into two smaller branches, which proceed along the contiguous sides of the great and second toe. — In this way the series of digital arteries for the supply of the under surface of the toes is rendered complete.
From Quain's anatomy.