242 ANATOMY OF THE LOWER EXTREMITY. 



may then be cut across just below the union of its heads, and the two 

 halves reflected. 



In dissecting up the heads of the gastrocnemius, the 

 strong character of their osseous attachment will be seen. 

 A sjnnovial bursa is sometimes found between the muscle 

 and the condyle on one or both sides, and a sesamoid bone 

 is occasionally developed in_the head attached to the outer 

 condyle. 



The PLANTARIS MUSCLE arises from the outer condyle of 

 the femur in common with the under part of the outer 

 head of the gastrocnemius ; it forms a short belly, from 

 two to four inches in length, terminating in a long, slender 

 tendon which crosses obliquely between the gastrocnemius 

 and soleus muscles, and passing downward along the inner 

 side of the tendo A chillis, is inserted by the side of that 

 tendon into the calcaneum. It is not always easy to sepa- 

 rate it from the tendo Achillis at its lower part. 



The SOLEUS MUSCLE arises from the head and upper half 

 of the fibula, and from the middle of the shaft of the tibia ; 

 it forms an elliptical-shaped belly, and joins the tendo 

 Achillis some distance below its commencement. A syno- 

 vial bursa is placed between the tendo Achillis and the 

 calcaneum above the point of its insertion, and a consider- 

 able interspace, filled with fat and cellular tissue, exists 

 between it and the layer of muscles beneath. 



The tendo Achillis is to be divided, and the soleus and plantaris 

 entirely removed ; in doing this, it must be remembered, that the deep 

 vessels and nerves, covered in by a fascia, lie between these muscles 

 and those beneath. 



A stout layer of fascia covers in the deep muscles and 

 vessels ; it extends from the popliteal space to the ankle- 

 joint, and is attached to the fibula on one side, and the 

 tibia on the other. 



The popliteal artery will be found dividing into the ante- 

 rior and posterior tibial arteries, and the course of the 

 anterior tibial artery, to the point where it perforates the 

 interosseous membrane, will now be seen. 



The posterior tibial artery descends the leg on the side 

 of the tibia, and, at the lower part of its course, becomes 

 comparatively superficial ; it runs along the tendo Achillis, 

 to the concavity formed by the internal malleolus and os 

 calcis, where it divides into the plantar arteries, which will 

 be seen in the dissection of the sole of the foot. It gives off 



