Pelvis

In adults, the shape of the pelvis can provide clues about whether an individual was male or female. Adult females have wider hips than males because the pelvis is built to be a birth canal. The skeletons of boys and girls younger than about 15 years are so similar that differences are not detectable. In order to determine the sex of this adult skeleton, certain features of the pelvis are examined. These features are discussed below.

Overall shape

The shape of the pelvis is different in females and males because females have babies and therefore have wider hips. The sides of the pelvis are parallel to each other in females, but the male pelvis is butterfly-shaped.

Dr. Mulhern’s Explanation

The sides of the pelvis in the frontal view are more parallel to each other than butterfly-shaped, which would suggest that the individual is female.

Subpubic Angle

The subpubic region is the place where the pelvic bones meet in the middle. The bone structure here is wider in females and shows a larger angle than in males due to the physical requirements of childbirth.

Dr. Mulhern’s Explanation

The subpubic region exhibits a very wide angle, suggesting that this individual is female.

Greater Sciatic Notch

The greater sciatic notch (when italicized anatomical names are clicked, the appropriate area of the skeleton is highlighted) is often wider in females than in males because females have wider hips than males.

Dr. Mulhern’s Explanation

The greater sciatic notch is wide, greater than a 90° angle. This feature suggests female sex.

Sacrum

The sacrum, which is the triangular-shaped bone at the base of the spine that connects the two hip bones is more curved in males than females.

Dr. Mulhern’s Explanation

The sacrum is not very curved, indicating that this individual may be female.

Ischium-Pubic Index

The two bones that make up the sides and front of the pelvis are called innominates, which means “no name.” Certain measurements of these bones can be used to help figure out if a skeleton is male or female. Each innominate is divided into three sections, including the ilium, ischium and pubis, which are actually three separate bones before they fuse together between about 13 and 15 years of age. In females, the pubis is longer than the ischium. In males, the pubis and ischium are more equal in length. This difference is due to the fact that females have wider hips than males.

Dr. Mulhern’s Explanation

The pubis in this skeleton measures 82 mm, while the ischium measures 78 mm. 82 ¸ 78 = approximately 1.05. 1.05 x 100 = 105. Therefore, the measurements of the pelvis would lead us to believe it is from a female because the Ischium-Pubic Index is greater than 84.

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