706 . THE VASCULAR SYSTEMS 



fifth metatarsal bone. It then turns obliquely inward to the interval between 

 ,the bases of the first and second metatarsal bones, where it anastomoses with the 

 communicating branch from the dorsalis pedis artery, thus completing the plantar 

 arch (arcus plantaris) (Fig. 488). As this artery passes outward, it is first placed 

 between the os calcis and Abductor hallucis, and then between the Flexor brevis 

 digitorum and Flexor accessorius, and as it passes forward to the base of the little 

 toe it lies more superficially between the Flexor brevis digitorum and Abductor 

 minimi digiti, covered by the deep fascia and integument. The remaining portion 

 of the vessel is deeply situated; it extends from the base of the metatarsal bone 

 of the little toe to the back part of the first interosseous space, and forms the 

 plantar arch; it is convex forward, lies below or on the plantar aspect of the 

 tarsal ends of the second, third, and fourth metatarsal bones and the correspond- 

 ing Interosseous muscles and upon the Adductor obliquus hallucis. 



Surface Marking. The course of the internal plantar artery is represented by a line 

 drawn from the mid-point between the tip of the internal malleolus and the centre of the con- 

 vexity of the heel to the middle of the under suface of the great toe; the external plantar by 

 a line from the same point to within a finger's breadth of the tuberosity of the fifth metatarsal 

 bone. The plantar arch is indicated by a line drawn from this point i. e., a finger's breadth 

 internal to the tuberosity of the fifth metatarsal bone transversely across the foot to the back of 

 the first interosseous space. 



Applied Anatomy. Wounds of the plantar arch arc always serious, on account of the 

 depth of the vessel and the important structures which must be interfered with in an attempt 

 to ligate it. They must be treated on similar lines to those of wounds of the palmar arches 

 (see page 654). Delorme has shown that the plantar arch may be ligated from the dorsum of 

 the foot in almost any part of its course by removing a portion of one of the three middle meta- 

 tarsal bones. 



Branches. The plantar arch, besides distributing numerous branches to the 

 muscles, integument, and fasciae in the sole, gives off the following branches: 



Posterior perforating. Digital. 



The posterior perforating (rami perforantes poster lores) are three small branches 

 which ascend through the back part of the three outer interosseous spaces, 

 between the heads of the Dorsal interossei muscles, and anastomose with the 

 interosseous branches from the metatarsal artery. 



The digital branches (aa. metatarseae plantares] are four in number, and supply 

 the three outer toes and half the second toe. It will be remembered that the 

 arteria princeps hallucis is the plantar digital branch of the communicating 

 rami in the first interosseous space and supplies the adjacent sides of the great 

 and second toes. The first digital branch of the plantar arch passes outward 

 from the outer side of the plantar arch, and is distributed to the outer side of the 

 little toe, passing in its course beneath the Abductor and short Flexor muscles. 

 The second, third, and fourth run forward along the interosseous spaces, and on 

 arriving at the clefts between the toes each divides into collateral digital branches 

 (aa. digitales plantares}, which supply the adjacent sides of the three outer toes and 

 the outer side of the second. At the bifurcation of the toes each digital artery 

 sends upward, through the fore part of the corresponding interosseous space, a 

 small branch which anastomoses with the interosseous branches of the metatarsal 

 artery. These are the anterior perforating branches (rami perforantes anteriores). 



From the description given it will be seen that both sides of the three outer toes 

 and the outer side of the second toe are supplied by branches from the plantar 

 arch; both sides of the great toe and the inner side of the second are supplied by 

 the communicating branch of the dorsalis pedis (princeps hallucis}. 



