THE LEG. 47 



The internal popliteal nerve, continuing the direction of the great sciatic, and 

 descending in the median line of the limb, is superficial to the vessels. The external 

 popliteal nerve is at first under cover of the fleshy belly of the biceps, and then lies 

 on the outer side of the ham, close behind the tendon of that muscle ; it 'may be felt 

 rolling beneath the finger as it crosses the outer side of the neck of the fibula, 

 before entering the peroneus longus muscle ; and it is sometimes to be seen giving 

 rise to a slight elevation in this position. 



The glands in the popliteal space are not to be felt unless they are enlarged. 



THE LEG- 



Along the fore part of the leg, the anterior border of the tibia is to be followed 

 downwards from the tubercle, constituting what is known as the shin. This 

 border is sharp in the upper two-thirds of the leg, and describes a slight curve with 

 the concavity outwards ; in the lower third the border disappears, and the bone is 

 concealed by the tendons of the anterior muscles. On the inner side of the shin, 

 the broad internal surface of the tibia is subcutaneous below the sartorius, and leads 

 downwards to the prominent internal malleolus. At the back of the latter process 

 a sharp edge is felt, which is formed by the inner margin of the groove for the 

 tendon of the tibialis posticus ; the tendon itself covers the posterior surface of the 

 malleolus, and is rendered prominent by inverting the foot. The head of the fibula 

 is subcutaneous, as has been before mentioned ; the shaft is surrounded by muscles, 

 bat it can be felt through them in the lower half at least of the leg, and it will be 

 remembered that it is placed considerably farther back in the leg than the shaft of 

 the tibia ; near the ankle, a triangular portion of the bone comes to the surface, and 

 is continued down to the external malleolus. 



Along the concavity of the anterior edge of the tibia, the prominence formed by 

 the fleshy belly of the tibialis anticus is seen, and external to this is the much less 

 distinct and narrower extensor longus digitorum. The tendons of the muscles 

 appear in the lower third of the leg, and between them also that of the extensor 

 proprius hallucis ; they are brought into view most distinctly by flexing the ankle 

 and extending the toes. From the head of the fibula downwards, the peroneus 

 longus and brevis muscles form an elongated swelling, from which the tendons can 

 be traced descending behind the external malleolus. Posteriorly the elevation of 

 the calf is formed by the gastrocnemius muscle, which terminates about the middle 

 of the leg in the tendo Achillis ; the inner head of the gastrocnemius is the larger, 

 and descends lower than the outer. On each side of the gastrocnemius and tendo 

 Achillis, a portion of the soleus comes to the surface ; and the characteristic form 

 of the gastrocnemius, depending upon the peculiar structure of the muscle (Vol. II, 

 p. 262), as well as the extent and shape of the projecting portions of the soleus, are 

 brought into view by raising the body on the toes. The tendo Achillis gradually 

 becomes narrower as it approaches the heel, but it widens again a little as it passes 

 over the tuberosity of the os calcis to its insertion. Between it and the malleolus, 

 on each side, is a well-marked hollow, that on the outer side being the deeper ; in 

 the inner of these, the tendons of the tibialis posticus and flexor longus digitorum, 

 and the posterior tibial vessels and nerve are superficial. 



Both the external and internal saphenous veins are visible beneath the skin of 

 the leg, together with numerous tributaries and communicating branches. The 

 internal is the larger, and, after crossing in front of the internal malleolus, runs 

 upwards just behind the inner border of the tibia ; the external passes behind the 

 outer malleolus and then ascends over the middle of the calf to the ham. Each 

 vein is accompanied by the nerve of the same name. 



The bifurcation of the popliteal artery takes place about two inches (5 cm.) below 



