Anatomic Study Of Obturator Nerve Outside Obturator Canal

Objective:Research on the diameter and length of obturator canal, and the length, width, thickness, as well as the number of branches of the obturator nerve outside the obturator canal, which will provide anatomic basis for clinical diagnosis and treatment of pelvic outlet syndrome.Materials and Methods:Doing 12 cases of dissecting(a total of 24 cases), of unknown age.8 male, 4 female, basin appearance without damage, and excluded pelvic lesions. Expose the area we study, measure the diameter and length of obturator canal, so as the obturator nerve branches and muscular branches. Then process data with statistical software.Results:(1) The obturator canal is the bone fiber canal of obturator nerve through pelvic cavity to thigh, the top of it is obturator foramen, below it is the obturator membrane, internal obturator muscle and external obturator muscle on the edge. The trend of canal is similar to inguinal canal, from the lateral forward inside. The outer canal mouth diameter is (4.22±8.8) mm , the length is (1.45±2.3 )mm.(2) The anterior and posterior branch bifurcation is more likely in the obturator canal, also existing basin branch and pipe branch. 2 cases exist basin branch, the average length between branch point and outer mouth of obturator membrane is(28.22±3.42)mm,maximum value 45.42mm, minimum value 24.26mm. 19 cases exist branch in obturator membrane, the average length between branch point and outer mouth of obturator membrane i(s20.13±3.32)mm, maximum value 37.43 mm, minimum value 7.87mm.3 cases exist branch outside the basin, the average length between branch point and outer mouth of obturator membrane is(13.62±2.34)mm, maximum value 21.81 mm, minimum value 12.34mm.(3) The width of anterior branch of obturator nerve is(5.13±0.42)mm, thickness is( 0.56±0.12)mm. The width of posterior is(3.04±0.64)mm, thickness is(0.51±0.14)mm.(4) The muscular branches of obturator nerve respectively: adductor longus branch , all come from anterior branch , the length is (80.31±6.42)mm,width is (8.65±2.13)mm,thickness is (1.95±0.34)mm, the number of final branches is 4.2; adductor brevis branch, more likely come from the anterior branch, a few from posterior branch, the length is (59.54±2.45)mm, width is (3.06±1.22)mm, thickness is (0.26±0.05)mm, the number of final branches is 2.3; gracilis branch, all come from the anterior branch, the length is (118.27±5.76)mm, width is (2.53±1.46)mm,thickness is (0.47±0.03)mm,the number of final branches is 4.8; pectineus branch,most come from the posterior branch, a few from nerve stem,the length is (16.02±2.45)mm,width is (1.85±0.39)mm,thickness is (0.28±0.02)mm,the number of final branches is 1.1; adductor magnus branch, all come from posterior branch,the length is (133.27±9.43)mm,width is (5.23±2.53)mm,thickness is (0.59±0.09)mm,the number of final branches is 5.6.Conclusion:(1) Implementation of pelvic external obturator nerve block anesthesia should be close to the superior ramus of pubis below needle(that is 1-2cm outer below the pubic node).(2) Carrying out surgery on pelvic outlet syndrome,make a curved incision from pectineus branch to thigh,cut the end of adductor longus off,turn it over,recognize anterior and posterior branches of obturator nerve and find the branches intersection along the nerve.(3) Doing obturator nerve amputation surgery should seach the anterior and posterior branches of obturator nerve and cut the branches or the trunk of obturator nerve at the obturator canal outside core.