[A macroscopical observation of the nerves to the pelvic floor muscles, the obturator internus and the quadratus femoris in some mammals].
Using dogs, cats, rabbits, guinea pigs and rats, the nerves to the Levator ani, the Coccygeus, the Obturator internus and the Quadratus femoris are observed and compared macroscopically. The main findings obtained are summarized as follows: The nerve to the Levator ani of dogs is one (95.0%) or two (5.0%) in number and arises most frequently from S2 and S3. That of rats is one in number and arises most frequently from S minus 1 (S-1) and S1. The nerve to the Coccygeus of dogs is one (70.0%) or two (30.0%) in number and arises most frequently from S2 and S3. That of rabbits is one (65.9%), two (24.4%) or three (9.7%) in number and arises most frequently from S2 and S3. The nerve to the Levator ani is observed in dogs and rats, but it is not observed in rabbits. The common trunk which is formed by the nerves to the pelvic floor muscles and the pelvic splanchnic nerves is observed in dogs and rats, but it is not observed in rabbits. The number of the nerves to the Obturator internus of dogs, cats and rabbits is either one or two. That of guinea pigs and rats is one. The number of the nerves to the Quadratus femoris of cats and guinea pigs is one. The common trunk which is formed by the originating root of the nerve to the Obturator internus and that of the nerve to the Quadratus femoris is observed in guinea pigs, but it is not observed in cats. The new classification in proposed according to the arising position of the nerve to the Obturator internus and the Quadratus femoris and classified into the following types: Type 1 (sciatic nerve type); the nerve arises from the main trunk of the sciatic nerve or it's originating root. Type 2 (transitional type); the nerve arises from the point where the bigeminal nerve joins the sciatic nerve. Type 3 (pudendal nerve type); the nerve arises from the pudendal nerve or it's originating root. The types most frequently observed are as follows; In dogs, cats, rabbits and rats the nerve to the Obturator internus is pudendal nerve type, and in guinea pigs it is transitional type. In cats the nerve to the Quadratus femoris is pudendal nerve type, and in guinea pigs it is transitional type.
D000818:Animals; D002415:Cats; D004285:Dogs; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009132:Muscles / Q000294:innervation; D010388:Pelvis / Q000294:innervation*; D011817:Rabbits; D051381:Rats