530 ARTERIES. 



Peculiarities in Size. The dorsal artery of the foot may be larger than usual, to compensate 

 for a deficient plantar artery ; or it may be deficient in its terminal brunches to the toes, which 

 are then derived from the internal plantar ; or its place may be supplied altogether by a large 

 anterior peroneal artery. 



Position. This artery frequently curves outwards, lying external to the line between the 

 middle of the ankle and the back part of the first interosseous space. 



Surgical Anatomy. This artery may be tied, by making an incision through the integument, 

 between two and three inches in length, on the fibular side of the tendon of the Extensor Pro- 

 prius Pollicis, in the interval between it and the inner border of the short Extensor muscle. 

 The incision should not extend further forwards than the back part of the first interosseoua 

 space, as the artery divides in that situation. The deep fascia being divided to the same extent, 

 the artery will be exposed, the nerve lying upon its outer side. 



Branches. The branches of the dorsalis pedis are, the 



Tarsal. Dorsalis hallucis (dorsalis pollicis). 



Metatarsal. Communicating. 



Interosseous. 



The tarsal artery arises from the dorsalis pedis, as that vessel crosses the 

 scaphoid bone ; it passes in an arched direction outwards, lying upon the tarsal 

 bones, and covered by the Extensor Brevis Digitorum ; it supplies that muscle 

 and the articulations of the tarsus, and anastomoses with branches from the 

 metatarsal, external malleolar, peroneal, and external plantar arteries. 



The metatarsal arises a little anterior to the preceding ; it passes outwards to 

 the outer part of the foot, over the bases of the metatarsal bones, beneath the 

 tendons of the short Extensor, its direction being influenced by its point of 

 origin; and it anastomoses with the tarsal and external plantar arteries. This 

 vessel gives off three branches, the interosseous, which pass forwards upon the 

 three outer Dorsal Interossei muscles, and, in the clefts between the toes, divide 

 into two dorsal collateral branches for the adjoining toes. At the back part of 

 each interosseous space these vessels receive the posterior perforating branches 

 from the plantar arch ; and at the fore part of each interosseous space, they are 

 joined by the anterior perforating branches, from the digital arteries. The 

 outermost interosseous artery gives off a branch which supplies the outer side 

 of the little toe. 



The dorsalis hallucis runs forwards along the outer border of the first meta- 

 tarsal bone, and, at the cleft between the first and second toes, divides into 

 two branches, one of which passes inwards, beneath the tendon of the Ex- 

 tensor Proprius Pollicis, and is distributed to the inner border of the great toe; 

 the other branch bifurcating to supply the adjoining sides of the great and 

 second toes. 



The communicating artery dips down into the sole of the foot, between the 

 two heads of the first Dorsal Interosseous muscle, and inosculates with the 

 termination of the external plantar artery, to complete the plantar arch. It 

 here gives off two digital branches; one runs along the inner side of the great 

 toe, on its plantar surface; the other passes forwards along the first metatarsal 

 space, and bifurcates for the supply of the adjacent sides of the great anc" 

 second toes. 



POSTERIOR TIBIAL ARTERY. (Fig. 299.) 



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The Posterior Tibial is an artery of large size, which extends obliquely down- 

 wards from the lower border of the Popliteus muscle, along the tibial side of 

 the leg, to the fossa between the inner ankle and the heel, where it divides 

 beneath the origin of the Abductor Pollicis, into the internal and external 

 plantar arteries. At its origin it lies opposite the interval between the tibia 

 and fibula ; as it descends, it approaches the inner side of the leg, lying behind 

 the tibia, and, in the lower part of its course, is situated midway between the 

 inner malleolus and the tuberosity of the os calcis. 



Relations. It lies successively upon the Tibialis Posticus, the Flexor Longus 

 Digitorum, the tibia and the back part of the ankle-joint. It is covered by the 



