MORPHOMETRIC STUDY OF SACRAL HIATUS

Sacrum is a large triangular bone. It is formed by fusion of five sacral vertebrae and forms the caudal region of the vertebral column. It forms the posterosuperior wall of the pelvic cavity wedged between the two hip bones. The opening present at the caudal end of sacral canal is known as sacral hiatus. It is formed due to the failure of fusion of lamina of the fifth (occasionally 4th) sacral vertebra. Sacral hiatus is used as an access port for administration of caudal epidural anesthesia in Obstetrics as well as in orthopedic practice for treatment and diagnosis. In this study, 25 adult dry sacrum were measured. It is found that 68 percent of bones have commonest shape of inverted U. The mean height of sacral hiatus is 24.25mm (range 15-60 mm). The mean width of sacral hiatus at sacral cornua is 10.33mm (range 7-12mm).The mean distance between two superolateral crest is 74.02mm (range 68-90mm). The mean distance from right superolateral crest to apex of sacral hiatus is 80mm (50-99.35mm). The mean distance from left superolateral crest to apex of sacral hiatus is 84mm (range 57-99.34mm).