[in Japanese]

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1. The nervous system of the pelvic floor in 55 (38 male and 17 female) cadavers of adult Japanese is observed.
2. The caudal termination of the spinal nerves is Co₁ (62 sides, 31 ind.) or Co₂ (44 sides, 22 ind.), exceptionally S₅ or Co₅ in one individium for each on both sides.
3. The terminal segment of the sympathetic trunk is the 3rd (18.18%), 4th (49.09%) or 5th (32.73%) sacral ganglion, which connects cranially with the respective spinal nerves. In 76 per cent or more of the cases the both sides trunks converge in a single ganglion, the ganglion impar, which sends 1 or 2 rami terminates ending immediately on the surface of the coccygeal bone. In the other 13 (24 per cent) cases in which the ganglion impar is deficient the terminal ganglion son each side communicate with one single nerve bundie (10 cases), or with double (2 cases). In the last one case there is no communication at the caudal ends (Tr₄) of the sympathetic trunk, but there is a single communication between both sides Tr2. For the formation of the ganglion impar the position of the terminal ganglion of the sympathetic trunk is inclined to come more frequently caudal. The most caudal spinal nerves connecting with the sympathetic trunk are S, or S.(in 92%).
4. Among the peripheral nerves of the pelvic floor the visceral are much more variable in the form than the parietal ones. The nervi splanchnici pelvini arise always in connection with S₃ and S₄, sometimes with addition of the branches of S₂ and S₅, exceptionally with that of S₁. The number of the nerves on one side is from 4 to 7 in 80 per cent of the cases. Among 55 specimens only one shows a perfect symmetry in the origin and distribution, so the forms of these nerves are almost always asymmetrical.
5. The nerve for levator ani comes from S₃, S₄ or S₃-S₄ anastomosis and single in number, those for m. coccygeus from S₃-Co₁ especially from S₆ S₅, and 2-5 in number, those for m. anococcygeus from Co₁ or Co₂ and 2 or 1 in number, those for m. sacroccygicus anterior from S₄ and S₅ and one in number.
6. The parietal nerves of the floor are, except n. musculi coccygici, much less variable in the form than the visceral ones. Among muscle nerves only that of m. coccyg. receives much more segmental nerves from S₂-Co₁.
7. Among the parietal muscle nerves the n.m. levat. ani is the only one which sends an anastomosis to the visceral splanchnici, its frequency is almost 13%, in which that of visceral to the n.m. levat. ani is included. The nn. splanchnici pelvini receive reinforcing branches directly from Tr₂-Tr₄ of the truncus sympat. hicus in more than 20 per cent of the sides examined.

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