THE LOWER LIMB 569 



sciatic artery is developed from the hypogastric portion (subsequently internal 

 iliac portion) of a common iliac artery. 



The external iliac and femoral arteries are formed at a later period, the 

 external iliac being a secondary outgrowth from the common ihac at a higher 

 level than the origin of the sciatic artery. The external iliac artery is con- 

 tinued into the femoral, and the femoral artery joins the pophteal artery at 

 the place where the sciatic artery is continued into that vessel. The sciatic 

 artery now undergoes retrogression, and the part of it between the popliteal 

 artery and the gluteal region for the most part disappears. The upper part 

 of the primitive vessel, however, persists, and forms the sciatic cirtery (arteria 

 gliitea inferior) of adult Ufe. 



Before the femoral artery joins the popliteal it gives off a fairly large 

 branch, which accompanies the internal saphenous vein, and is called the 

 internal saphenous artery. This vessel for the most part atrophies, but its 

 upper portion persists and represents the superficial branch of the arteria 

 anastomotica magna. The posterior tibial artery is developed from the upper 

 part of the peroneal artery. 



Development of Veins of Lower Limbs. 



The veins of the lower limb form two groups — superficial and deep. The 

 superficial veins are developed prior to the deep, the latter accompanying the 

 arteries. 



The primitive vein of each lower limb is the primary fibular, or post-axial, 

 vein, which opens proximally into the posterior cardinal vein. From the 

 primary fibular vein a temporary anterior tibial vein is developed. The 

 long saphenous vein grows distally from the posterior cardinal vein. A 

 temporary posterior tibial vein is developed from the long saphenous vein. 



The primary fibular vein, which is originally continuous with the sciatic 

 vein, loses its connection with that vessel, and persists as the short saphenous 

 vein. 



THE ANKLE-JOINT. 



The ankle-joint belongs to the class diarthrosis, and to the sub- 

 division ginglymus. The articular surfaces are the lower extremity 

 of the shaft and the outer surface of the internal malleolus of the 

 tibia, the inner surface of the external malleolus of the fibula, and 

 the superior and both lateral surfaces of the astragalus. The 

 ligaments are anterior, posterior, internal lateral, and external 

 lateral. 



The anterior ligament is a thin membrane which covers the 

 joint in front. Superiorly it is attached from within outwards 

 to the anterior border of the internal malleolus, anterior surface of 

 the lower end of the tibia two or three lines above the anterior 

 border, anterior inferior tibio-fibular ligament, and anterior border 

 of the external malleolus. Inferiorly it is attached to a groove on 

 the upper aspect of the head of the astragalus, immediately behind 

 the cartilaginous surface and in front of the neck. The fibres of the' 

 ligament are chiefly disposed in a transverse direction. 



In addition to the tendons which lie upon it, this ligament is 

 related to the anterior tibial vessels and nerve. Its deep surface 

 is covered by the synovial membrane of the joint, and inferiorly is 

 in contact with a collection of fat which lies in the hollow on the 

 upper surface of the neck of the astragalus. 



