856 THE NERVOUS SYSTEM. 



usually two in number and pass inward behind the femoral vessels, and enter the 

 muscle on its anterior surface. Sometimes one of these nerves is given off in the 

 pelvis, and is then often united with the accessory obturator. The Sartorius is 

 supplied by filaments which arise in common with the middle cutaneous nerve and 

 enter the upper part of the muscle. 



Posterior Division. The long or internal saphenous nerve is the largest of the 

 cutaneous branches of the anterior crural. It approaches the femoral artery 

 where this vessel passes beneath the Sartorius, and lies at first on its outer side 

 and then crosses over it, beneath the aponeurotic covering of Hunter's canal, as 

 far as the opening in the lower part of the Adductor magnus. It then quits the 

 artery, and descends vertically along the inner side of the knee, beneath the Sar- 

 torius, pierces the fascia lata, opposite the interval between the tendons of the 

 Sartorius and Gracilis, and becomes subcutaneous. The nerve then passes along 

 the inner side of the leg, 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, termi- 

 nating at the inner ankle ; the other passes in front of the ankle, and is distrib- 

 uted to the integument along the inner side of the foot, as far as the great toe, 

 communicating with the internal branch of the musculo-cutaneous nerve. 



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

 cating branch which joins the plexus formed by the obturator and internal cuta- 

 neous nerves. 



At the inner side of the knee it gives off a large branch (nervus cutaneus 

 patellce) which pierces the Sartorius and fascia lata, and is distributed to the 

 integument 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 plexus patellae. The cutaneous nerve of the patella is occasionally 

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

 in front of the knee. 



Beloiv 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 are as follows : 



The branch to the Rectus muscle 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 

 descending 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 company with the internal saphenous nerve for 

 its upper part. 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 branch to the Crureus enters the muscle on its anterior surface about 

 the middle of the thigh, and sends a filament through the muscle to the Sub- 

 crureus. Articular branches to the hip-joint are derived from some of the other 

 muscular branches as well as from the nerve to the Rectus. 



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

 slender filament, is derived from the nerve to the Vastus externus. It penetrates 

 the capsular ligament of the joint on its anterior aspect. The other is derived 

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

 the surface of this muscle to near the joint; it then penetrates the muscular fibres, 

 and accompanies the deep branch of the anastomotica magna artery, pierces 

 the capsular ligament of the joint on its inner side, and supplies the synovial 

 membrane. 



