THE DORSAL ARTERY OF THE FOOT. 503 



peroneal, external plantar, and metatarsal arteries. It furnishes offsets to the 

 extensor brevis digitorum, and to the tarsal articulations. 



2. The metatarsal artery, arising near the bases of the metatarsal bones, is 

 also directed outwards beneath the short extensor muscle, and terminates in 

 branches which anastomose with offsets of the tarsal and external plantar arteries. 

 It supplies small branches to the extensor brevis digitorum muscle and the articu- 

 lations of' the foot, and from the fore part of the arch formed by the vessel three 

 dorsal interosseous arteries are given off. 



The dorsal interosseous arteries (vi) pass forwards over the outer-three inter- 

 metatarsal spaces, resting upon the dorsal interosseous muscles, to which they 

 furnish small offsets. Opposite the metatarso-phalangeal articulations each artery 

 divides into two dorsal digital branches, which run along the contiguous borders of 

 the corresponding toes. These arteries communicate with the plantar arch at the 

 back part of the interosseous spaces by means of the posterior perforating branches, 

 and, less constantly, with the plantar digital arteries at the fore part of the spaces 

 by the anterior perforating branches. From the outermost interosseous artery, or 

 from the metatarsal artery itself, a small branch is given off to the outer border of 

 the little toe. 



3. The first dorsal inter osseous artery (v), continuing the direction of 

 the dorsal artery of the foot, runs forwards over the dorsal interosseous muscle of 

 the first space, communicates with the corresponding plantar digital artery by an 

 anterior perforating branch, and divides into dorsal digital branches for both sides 

 of the great toe, and the inner side of the second toe. The branch to the inner side 

 of the great toe is, however, frequently small or wanting. 



4. The plantar digital branch passes forwards in the first interosseous space, 

 sends inwards across the first metatarsal bone the artery for the inner side of the 

 great toe, and terminates by dividing into collateral digital branches for the 

 adjacent sides of the first and second toes. 



Varieties of the anterior tibial artery. Origin. In instances of early division of the 

 popliteal artery, the place of origin of the anterior tibial is necessarily higher than usual, and 

 in these cases the commencement of the vessel may either descend by the side of the posterior 

 tibial artery behind the popliteus, or it may pass in front of that muscle, resting against the 

 outer tuberosity of the tibia, to reach the upper end of the interosseous space. The peroneal 

 artery is occasionally found conjoined with the anterior tibial, that vessel having either a 

 normal or a high origin. 



Course. The anterior tibial artery has been observed inclining outwards towards the 

 fibula in the lower part of the leg, and then returning to its ordinary position on the dorsum 

 of the foot. It has also been seen coming to the surface in the middle of the leg, and con- 

 tinued downwards from that point, covered only by the fascia and the integument (Pelletan, 

 Velpeau). Velpeau also states that in one case the artery gained the front of the leg by 

 passing with the musculo-cutaneous nerve round the outer side of the fibula. 



Size. This vessel is more frequently diminished than increased in size. 



It may be defective in various degrees. Thus, the dorsal artery of the foot may fail to 

 enter the sole, and the digital branches to the great and second toes are then derived from the 

 external or the internal plantar division of the posterior tibial. In a farther degree of dimi- 

 nution, the anterior tibial ends at the ankle, or in the lower part of the leg ; its place is 

 then taken by the anterior peroneal artery, which forms the dorsal artery of the foot, the two 

 vessels (anterior tibial and anterior peroneal) being either connected together or separate. 



A few cases are recorded 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 peroneal artery. 



This artery is occasionally larger than usual, in that case compensating for a defective 

 condition of the external plantar artery. 



The dorsal artery of the foot is not unfrequently found curving outwards below the 

 ankle-joint, and returning to its usual position at the back of the first interosseous space. It 

 has also been seen passing through the second space into the sole. 



The metatarsal artery varies greatly in its arrangement. It is sometimes given off higher 

 than usual, and it occasionally arises in common with the tarsal artery. It may be smaller 



