THE LUMBAR PLEXUS. 787 



the long saphenous nerve, and gives off several cutaneous branches. The nerve 

 then passes down the inner side of the leg, to the integument of which it is 

 distributed. This nerve, beneath the fascia lata, at the lower border of the 

 Adductor longus, joins in a plexiform network by uniting with branches of the 

 long saphenous and obturator nerves (Fig. 419). When the communicating branch 

 from the obturator nerve is large and continued to the integument of the leg, the 

 inner branch of the internal cutaneous is small and terminates at the plexus, 

 occasionally giving off a few cutaneous filaments. 



The internal cutaneous nerve, before dividing, gives off a few filaments, which 

 pierce the fascia lata, to supply the integument of the inner side of the thigh, 

 accompanying the long saphenous vein. One of these filaments passes through 

 the saphenous opening ; a second becomes subcutaneous about the middle of the 

 thigh ; and a third pierces the fascia at its lower third. 



Muscular Branches of the Anterior Division. The nerve to the Pectineus is 

 often duplicated ; it arises from the anterior crural immediately below Poupart's liga- 

 ment, and passes inward behind the femoral sheath to enter the anterior surface of 

 the muscle. The nerve to the Sartor ius arises in common with the middle cutaneous. 



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 in front of 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 Sartorius, 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, 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 musculo-cutaneous nerve. 



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

 communicating branch which joins the plexus formed by the obturator and internal 

 cutaneous nerves. 



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

 cutaneus patellae) 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 patellce. 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. 



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 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. 



