Greater Sciatic Notch
Definition
The posterior notch on the ilium between the posterior inferior iliac spine and the ischial spine. Narrow and V-shaped in males; wide and U-shaped in females. Scored on Walker 2005 five-point ordinal scale.
- Location
- Posterior ilium, between PIIS and ischial spine
- Male morphology
- Narrow, V-shaped
- Female morphology
- Wide, U-shaped
- Scoring system
- Walker (2005) five-point ordinal scale
Common questions
Why is the greater sciatic notch considered one of the more reliable pelvic sex indicators?+
It reflects an obstetric adaptation, a wider notch accompanies the broader pelvic outlet needed for childbirth, so the sexual dimorphism is functionally driven rather than incidental, which makes it more consistent across populations than many cranial traits.
How does the Walker scoring approach reduce subjectivity compared to a simple visual call?+
Instead of a binary male or female judgement, the observer scores the notch on a five-point ordinal scale from clearly male to clearly female shape, and that score is then combined statistically with scores from other pelvic traits, which reduces the impact of any single ambiguous observation.
Related terms
- Klales 2012 Revision
- An ordinal revision of the Phenice method by Ashley Klales using a 1-5 scale for each trait and a logistic regression to...
- Obstetric Trade-Off
- The evolutionary conflict in humans between the biomechanical benefit of a narrow pelvis for efficient bipedal locomotion and the obstetric requirement for...
- Phenice Method
- A non-metric morphological sex estimation technique published by Thomas Phenice in 1969, based on scoring three traits of the pubic bone: the...
- Pre-Auricular Sulcus
- A groove anterior to the auricular surface of the ilium, associated with parturition stress at the sacroiliac joint. Present in 58-70 per...
- Subpubic Angle
- The angle at the inferior apex of the pubic arch where the two inferior pubic rami meet. Acute (below 90 degrees) in...
- Subpubic Concavity
- A medial inward curve on the inferior aspect of the ischiopubic ramus in females, resulting from the wider sub-pubic space. Absent (straight...
- Terry Collection
- A documented skeletal collection at the Smithsonian National Museum of Natural History (Washington DC), assembled from cadavers donated to Washington University's anatomy...
- Ventral Arc
- An elevated ridge on the anterior (ventral) surface of the pubic bone, curving from the pubic symphysis toward the ischiopubic ramus. Present...
- Walker 2005 Scale
- A five-point ordinal scoring system for the greater sciatic notch published by Philip Walker, ranging from 1 (very narrow, most male) to...