Morphometric Analysis of the Foramen Magnum in Dry Human Skulls in Northeastern Brazil

Abstract

Introduction The successful identification of the deceased is vital to the progress of any forensic investigation. This process of identification is facilitated by the determination of age, gender, and ethnicity. One of the main biological traits to be established from skeletal remains is the gender of the individual. In situations in which there are fragmented and mutilated skeletal remains, gender determination is relatively difficult, and it becomes important to establish the accuracy of individual bones. The basal region of the occipital bone is covered by a large volume of soft tissue and is therefore in a relatively well-protected anatomical position and, as such, classification of gender using the occipital bone may prove to be useful in cases of significantly disrupted remains. The present study aims to describe and analyze the morphological aspects of the foramen magnum (FM) in the population of the northeastern region of Brazil. Material and Methods A total of 159 dry skulls (88 males and 71 females) were subjected to measurement by a digital caliper (DIGIMESS®, Instrumentos de Precisão Ltda., São Paulo, Brazil) and was assessed for anteroposterior diameter (APD) and transverse diameter (TD), FM area, FM index (FMI), anterior, posterior and maximum lateral intercondylar distance. The measurement of all of these parameters sought to classify the FM in nine different types. Results The pentagonal type was the most found in males (11.31%), and the biconvex in females (18.86%). The less frequent type in males was the pear type (2.53%), and in females the less frequent types were the pentagonal and the heptagonal types (2.53% each). Using the traditional anthropological classification of Martin et al,13 the most common type of FM was the brachytrematous, with 49.68% of the total skulls. The APD, TD and FM area were higher in males than in females, only in the oval FM type. Conclusion The sexual dimorphism of the dimensions of the FM is established. However, there is a wide variability in the shape and measures in different populations, and to our knowledge this is the first study that shows the different types of the FM in the population of the northeastern region of Brazil.