Determination of sex from mastoid triangle amongnorth Indians

Determination of sex from the skeleton is vital to medico-legal investigations. The mastoid region is analysed for determination of sex from fragmentary crania in forensic anthropology as it is one of the most protected region and resistant to damage due to its anatomical position at the base of the brain.

The purpose of this study was to determine the existence of sexual dimorphism in the area of mastoid triangle related to three cranoimeteric points i.e. Porion, Asterion and Mastoidale among North Indians.

Material for the study consisted of 90 adult (above 18 years) human skulls (45 of either sex) of North Indians obtained from Anatomy and Forensic Medicine department of Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar. On each skull the three craniometeric points were marked on each side. All the lineal dimensions, Porion-Asterion, Asterion-Mastoidale, Mastoidale-Porion, were taken in millimeters with the help of sliding Vernier Caliper. Perimeter, area and the angles of mastoid triangle of both the sides and total area of mastoid triangle was calculated.

The value of area was 615.93 mm² (Right) & 618.53 mm² (left) and total area was 1234.46 mm² for males and value of area was 517.18 mm² (right) & 507.96 mm² (left) and total area was 1025.13 mm² for females. Mann-Whitney test was used to study the sex differences in the different variables. ROC curve (Receiver Operating characteristic) was used for testing the overall ability of the variables in sex estimation.

The mean of mastoid triangular area in males was significantly larger than those of the female (p <0.01). Therefore, mastoid triangle can be used as a tool for determination of sex in fragmentary skeletal remains.