抄録
Detailed dissections were performed on some primates and adult cadavers to provide more accurate morphological data on the composition of the pelvic diaphragm, pudendal plexus and sacral autonomic nerves.
1) The pelvic diaphragm is generally divided into 2 parts, the ventral iliopubococcygeus (levator ani: man) and the dorsal ischiococcygeus (coccygeus: man). This laminate arrangement is distinct in macaque monkeys. In man it becomes obscure and 2 parts are blended into one sheet. Some fibers of the pubococcygeus become attached to the rectal wall and form the levator ani. This attachment has been observed in chimpanzees and gibbons. 2) The pudendal plexus is divided into 2 parts, medial and lateral at their origin. From the 2 parts, 3 nerves originate respectively. In primates as in man a laminate arrangement exists among the 3 nerves from the medial: The pelvic splanchnic nerves (PSN) are situated ventrally, the nerve to the ischiococcygeus dorsally, the nerve to the iliopubococcygeus in between. The same laminate arrangement exists among the 3 nerves from the lateral: The dorsal nerve of the penis (or clitoris) is situated ventrally, the inferior rectal nerve dorsally, the perineal nerve in between. In the macaque monkey, no obvious laminate arrangement exists and in the gibbon and chimpanzee tends to be more distinct, but is not as obvious as in man. 3) Sacral autonomic nerves are composed of PSN (parasympathetic) and sacral splanchnic nerves (SSN) (sympathetic). PSN exist always in man and primates. But, SSN are observed in 21 out of 60 pelvic halves (35.0%) in man, and none are observed in primates with the only exception of chimpanzees. SSN in primates can be considered part of PSN, and in man they have developed to become independent nerves.
