A Morphologieal Study of the Sacrum in Korean Adult

The composition and the structure of the sacrum present the sexual and the racial difference. The variation of the structure is meaningful in the administration of caudal anesthesia which used one of the safest and the most valuable means of local anesthesia. In this study, a morphological investigation of the sacrum in Korean adults was done using 145 dry sacral bones. Non-metrical morphological variations were observed and ten measurements were undertaken. The results of the study were as follows. 1. The five segmented sacrum appeared most commonly (62.1%). Six segmented sacrum appeared 37.2% and the incidence tended to increse according to the age. Four segmented sacrum was noted in one case (0.7%). 2. In 9.7%, deficiences existed in the upper dorsal wall of the sacral canal. In 5.5%, deficiences existed in the middle of the dorsal wall of the sacral canal. 3. The apex of the sacral hiatus was found mostly (28.9%) at the upper third of the body of fifth sacral vertebra. 4. The sacral hiatus was classified into five groups by shape with triangular being the most frequent. 5. There was a significant sexual difference in the antero-posterior and transverse diameters of the first sacral vertebral body, the length of the sacrum, and the length of the sacral hiatus. 6. The average sacral index I was 98.2 in male, and 104.4 in female. Sacral index I was the relationship between the greaster breath to the length of the sacrum. 7. The average sacral index II was 46.6 in male, and 44.8 in female. Sacral index II was the relationship between the first sacral body diameter to the greaster breath of the sacrum. A thorough knowledge of the anatomical features of the dorsum of the sacrum including above results will lead to the decrease in the number of failures in administration of caudal anesthesia.