Identification of rib number and assessment of intercostal variation at the sternal rib end.

A technique for the identification of anatomical rib number is presented here. Preliminary tests indicate that with experience, percent accuracy for identification may approach 100%. This technique was then applied to a skeletal collection where rib number was not documented in order to determine the effects of intercostal variation on the application of rib four age-at-death estimation standards to other ribs. Spearman rank correlations between rib four and ribs three through nine range from 0.89 to 0.91. No significant differences were found between ribs conforming to or deviating from the phase observed on rib four. There is a significant proportion of deviations falling below the phase set by rib four, however these deviations are not statistically associated with rib number and are usually within one phase. These results indicate that rib four standards can be cautiously applied to other sternal ends when rib four is not preserved.