1054 



THE NER VE SYSTEM 



subcutaneous. The nerve then passes along the inner side of the leg (Fig. 770), 

 accompanied by the internal saphenous vein, descends behind the internal border 

 of the tibia, and at the lower third of the leg divides into two branches; one 

 continues its course along the margin of the tibia, terminating at the inner ankle; 

 the other passes in front of the ankle, and is distributed to the integument along 

 the inner side of the foot, as far as the great toe, communicating with the internal 

 branch of the musculocutaneous nerve. 



The long saphenous nerve about the middle of the thigh gives off a communicating 

 branch which joins the subsartorial plexus. 



At the inner side of the knee it gives off a large patellar branch (ramus infrapatel- 

 laris), which pierces the Sartorius and fascia lata, and is distributed to the integu- 

 ment in front of the patella. This nerve communicates above the knee with the 

 anterior branch of the internal cutaneous and with the middle cutaneous; below 

 the knee, with other branches of the long saphenous; and on the outer side of the 

 joint, with branches of the external cutaneous nerve, forming a plexiform network, 

 the patellar plexus (plexus patellae). The patellar branch is occasionally small, 

 and terminates by joining the internal cutaneous, which supplies its place in front 

 of the knee. 



Below the knee the branches of the long saphenous nerve are distributed to the 

 integument of the front and inner side of the leg, communicating with the cutaneous 

 branches from the internal cutaneous or from the obturator nerve. 



The Muscular Branches of the Posterior Division supply the four parts of the 

 Quadriceps extensor muscle. 



The branch to the Rectus femoris enters its under surface high up, sending off a 

 small filament to the hip-joint. 



The branch to the Vastus externus, of large size, follows the course of the descend- 

 ing branch of the external circumflex artery to the lower part of the muscle. It 

 gives off an articular filament to the knee-joint. 



The branch to the Vastus internus is a long branch which runs down on the 

 outer side of the femoral vessels in conipany with the long saphenous nerve. 

 It enters the muscle about its middle, and gives off a filament which can usually 

 be traced downward on the surface of the muscle to the knee-joint. 



The branches to the Crureus are two or three in number, and enter the muscle 

 on its anterior surface about the middle of the thigh; a filament from one of these 

 descends through the muscle to the Subcrureus and the knee-joint. 



The articular branch to the hip- joint is derived from the nerve to the Rectus 

 muscle. 



The articular branches to the knee-joint are three in number. One, a long slender 

 filament, is derived from the nerve to the Vastus externus muscle; it penetrates 

 the capsular ligament of the joint on its anterior aspect. Another is derived from 

 the nerve to the Vastus internus muscle. It can usually be traced downward 

 on the surface of this muscle to near the joint; it then penetrates the muscle and 

 accompanies the deep branch of the anastomotica magna artery, pierces the cap- 

 sular ligament of the joint on its inner side, and supplies the synovia! membrane. 

 The third branch is derived from the nerve to the Crureus. 



The Anterior or Ventral Divisions of the Sacral and Coccygeal Nerves 

 (rami anter lores) (Fig. 774). The anterior primary divisions of the sacral and 

 coccygeal nerves form the sacral and pudendal plexuses. The anterior divisions 

 of the upper four sacral nerves enter the pelvis through the anterior sacral foramina, 

 that of the fifth between the sacrum and coccyx, while that of the coccygeal 

 nerve curves forward below the rudimentary transverse process of the first piece 

 of the coccyx. The first and second sacral are large; the third, fourth, and fifth 

 diminish progressively from above downward. Each nerve receives a gray 

 ramus communicans from the corresponding ganglion of the sympathetic cord, 



