592 THE BLOOD-VASCULAR SYSTEM. 



metatarsal bones, where it anastomoses with the communicating branch from tlie 

 dorsalis pedis artery, thus completing the plantar arch. 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 

 upon the Interossei muscles opposite the tarsal ends of the metatarsal bones, and 

 is covered by the Adductor obliquus hallucis, the flexor tendons of the toes, and 

 the Lumbricales. 



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 surface 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. 



Surgical Anatomy. Wounds of the plantar arch are 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 545). Delorme has shown that it 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 metatarsal 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 Anterior Perforating. 



The Posterior Perforating 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 meta- 

 tarsal artery. 



The Digital Branches are four in number, and supply the three outer toes and 

 half the second toe. The first passes outward from the outer side of the plantar 

 arch, arid 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 divide into collateral branches, 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 inosculates with the interosseous branches 

 of the metatarsal artery. These are the anterior perforating branches. 



From the arrangement already described of the distribution of the vessels to 

 the toes 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. 



