Obturator Nerve 359 



(behind the pectineus and adductor longus) and ends in the obturator 

 plexus, though it sometimes wanders thence to the skin on the inner 

 side of the upper part of the leg. In its course it gives a branch to the 

 hip-joint, and branches to the adductors longus and brevis, the gracilis, 

 and the pectineus. Its articular branch enters through the cotyloid 

 notch and is chiefly distributed to the ligamentum teres. 



At the lower border of the adductor longus, beneath the sartorius, the 

 superficial part of the obturator nerve joins with branches of the internal 

 cutaneous and of the internal saphenous to form the obturator plexus. 



The deep division of the obturator nerve enters the thigh through 

 the substance of the obturator externus, which it supplies, and descends 

 behind the adductor brevis and in front of magnus, supplying both those 

 muscles. It then passes through the large adductor into the upper part 

 of the popliteal space, and, after resting upon the popliteal artery, enters 

 the knee-joint, probably in company with the central articular artery. 



Peripheral neuralgias are apt to disturb the obturator nerve in 

 disease of the hip, sacro-iliac, and mid-lumbar joints. Pain in the 

 knee, or the thigh over the region of the obturator plexus, is one of the 

 most usual and early symptoms of hip-disease. I cannot explain the 

 cause of this, but must content myself with calling attention to the fact 

 that the superficial division sends a twig to the ligamentum teres, and 

 that the deep division ends in the knee-joint. Analogous instances 

 of the transference of neuralgia are : pain at the end of penis, sympto- 

 matic of vesical calculus, and at the point of the shoulder, of aortic 

 disease or of hepatic disease. The fact of the obturator nerve 

 supplying also the sacro-iliac joint (Hilton) accounts for the pain about 

 the knee in disease of that synchondrosis. The weariness and aching 

 of the thighs and knees in lumbar caries is readily explained by the 

 effect of inflammatory pressure not only upon the obturator nerve but 

 upon other branches of the plexus situated in the diseased region of 

 the spine. The great feature in these pains is the symmetry of their 

 arrangement. The child complains of both thighs or knees aching. 

 When, after rest, the pains cease to be symmetrical, and are confined 

 to or chiefly felt upon one side, the formation of abscess in the sheath 

 of the psoas must be suspected. 



The accessory obturator, an occasional branch of the third and 

 fourth nerves, runs along the inner border of the psoas, and out of the 

 pelvis over the horizontal ramus of the pubes and beneath the pectineus 

 which it supplies. It also gives a twig to the hip-joint, and then merges 

 its filaments with those of the superficial part of the obturator nerve. 



The anterior division of the fifth lumbar nerve emerges below the 

 fifth lumbar vertebra, and is at once joined by a branch from the 

 fourth. The nerve thus formed is called the lumbo -sacral cord ; it 

 descends from the inner border of the psoas beneath the common iliac 

 vessels, and joins in the formation of the sacral plexus ; many of its 

 strands, however, pass out into the superior gluteal nerve. 



