464 SURGICAL APPLIED ANATOMY. [Chap. xxm. 



centre of the convexity of the heel. The internal 

 vessel follows a line drawn from this point to the 

 middle of the under surface of the great toe. The 

 external vessel crosses the sole obliquely to within a 

 thumb's breadth of the base of the fifth metatarsal 

 bone. From thence it turns more transversely across 

 the foot, running inwards over the bases of the meta- 

 tarsal bones to inosculate with the dorsalis pedis artery 

 at the back of the first interosseous space. On the 

 dorsum of the foot the subcutaneous veins may be seen 

 forming an arch convex towards the toes, and from 

 the ends of the arch vessels may be followed into the 

 internal and external saphenous veins. 



The ankle and foot. The skin about the 

 ankle and over the dorsum of the foot is thin and but 

 loosely attached to the subjacent parts. It becomes 

 readily excoriated, as is often the case where splints 

 or instruments have been improperly applied. Since the 

 skin over the malleoli lies directly upon the bone, while 

 that covering the dorsum of the foot is but slightly 

 separated from the bones of the tarsus, it follows that 

 the integuments in this region are readily contused, 

 and may suffer gangrene from an amount of pressure 

 that would cause but little trouble in other parts. 

 Over the sole the integument is dense and thick in all 

 those parts that come in contact with the ground. In 

 the normal foot, the heel, the outer margin of the foot, 

 and the line of metatarso-phalangeal joints are in 

 contact with the ground when the sole is placed flat 

 upon it. Along the inner margin of the foot the 

 integument is -thin and fine. The skin of the sole, 

 like that of the palm of the hand, is remarkably 

 adherent to subjacent parts. When cut it shows no 

 tendency to gape, and thus exploratory incisions made 

 into the part (as for the discovery of foreign sub- 

 stances) have often to be of greater dimensions than 

 would be needed elsewhere. 



