48 SUPERFICIAL ANATOMY OF THE LOWER LIMB. 



the knee-joint, and on a level with the lower part of the tubercle of the tibia. The 

 course of the anterior tibial artery is marked on the front of the leg by a line drawn 

 from a point midway between the head of the fibula and the prominence of the outer 

 tuberosity of the tibia to the centre of the ankle-joint. The intermuscular space in 

 which the artery lies is also indicated by a depression which is seen at the outer 

 border of the tibialis anticus when the muscle is called into action. The posterior 

 tibial artery runs from the centre of the ham to the mid-point of a line drawn from 

 the tip of the internal malleolus to the lower end of the inner border of the calcanean 

 tuberosity ; beneath this spot, the vessel divides into the internal and external 

 plantar arteries. The posterior tibial artery is covered by the gastrocnemius and 

 soleus for about two-thirds of its length, but in the lower third it is superficial, and 

 may be felt pulsating in the interval between the tendo Achillis and the tibia. 

 About three inches (7'5 cm.) below the knee, it gives off the large peroneal branch, 

 which follows the direction of the fibula, and terminates behind the external 

 malleolus. 



THE ANKLE AND FOOT. 



Of the two malleoli, the internal is usually the more prominent, but the external 

 descends lower and also projects farther back, having its point, as a rule, about 

 three-quarters of an inch (2 cm.) nearer to the heel than that of the internal malleolus. 

 On the dorsum of the foot, the tarsal bones are not usually to be distinguished individu- 

 ally, but the head of the astragalus not unf requently forms a considerable projection 

 when the ankle-joint is extended ; and if the arch of the foot is flattened, it often 

 protrudes markedly on the inner side. Along the inner side of the foot, the tube- 

 rosity of the os calcis is first felt, and then, about an inch (2*5 cm.) below the internal 

 malleolus, the sustentaculum tali of the same bone ; in front of the latter, and 

 about an inch and a half (4 cm.) from the malleolus, the tuberosity of the navicular 

 bone is prominent, and to it the tendon of the tibialis posticus may be followed from 

 the back of the internal malleolus ; the finger next passes over the internal cuneiform 

 bone, and recognizes the base of the first metatarsal bone as a slightly prominent 

 ridge ; from this, the shaft of the bone may be traced forwards beneath the skin to 

 its expanded, and often unduly prominent, head, below which the sesamoid bones 

 may be felt on the plantar aspect of the mctatarso-phalangeal articulation. On the 

 outer side of the foot, nearly the whole of the external surface of the os calcis is sub- 

 cutaneous, and the peroneal spine of the bone may often be felt a little below and in 

 front of the external malleolus. The anterior extremity of the os calcis may be 

 distinguished when the foot is inverted, forming a marked prominence above the 

 level of the cuboid bone, and in front of this, distant about two and a half inches 

 (G cm.) from the external malleolus, the projecting tuberosity at the base of the fifth 

 metatarsal bone is easily felt. 



The interarticular cleft of the ankle-joint is placed about half an inch (1 cm.) 

 above the tip of the internal malleolus. The transverse tarsal articulation, at which 

 Chopart's amputation is practised, runs from immediately behind the tuberosity of 

 the navicular bone, outwards in front of the head of the astragalus and the anterior 

 extremity of the os calcis, to end a little in front of the mid-point between the tip of 

 the external malleolus and the tuberosity of the fifth metatarsal bone. The line of 

 the tarso-metatarsal articulations is very irregular : commencing immediately 

 behind the base of the first metatarsal bone, it passes at first transversely between 

 that bone and the internal cuneiform, then turns sharply backwards for a full half- 

 inch (15 mm.) to reach the cleft between the middle cuneiform and second 

 metatarsal bones, next advances for about a quarter of an inch (5 mm.), and then is 

 continued outwards, with a slight inclination backwards, between the outer three 



