ABSTRACT
Background: Non metric cranial variants have always been a topic of considerable interest for research workers, as they possess racial, regional and sex dimorphic differences. These variants are also of anthropometric, genetic, morphological and forensic importance. Material and Methods: 71 skulls from north indian region were studied to analyse the prevalence of variations in number and location of mastoid foramen and to draw significant inferences. Results: Prevalence of absent mastoid foramen is 5.19%, while bilateral prevalence of absent mastoid foramen is only 1.29%, however unilaterally mastoid foramen is absent in 3.9%. Prevalence of single, double, triple and quadruple mastoid foramina was 75.97%, 19.48%, 1.95% and 2.6% respectively. Amongst all mastoid foramina in 71 skulls, 23.38% foramina were exsutural, out of which 20.13% were present on temporal bone and 3.25% were present on occipital bone. Conclusions: Findings are discussed and compared with other global studies and are found to be of considerable racial and regional significance. Knowledge of this variant can be valuable in some neurosurgical procedures.