Forensic Anthropology The Pelvic Girdle

THE PELVIS The many names for this region Pelvis: composed of 2 innominate bones and the sacrum Innominate (or Os Coxae): each half of the “pelvic bowl” formed by the fusion of Ilium Ischium Pubis USE INNOMINATE WHEN COMPLETE USE INDIVIDUAL BONE NAMES WHEN SEPARATE OR TO REFERENCE A SPECIFIC BONE OR FEATURE

THE INNOMINATE ILIUM – most superior of the 3 the blade ISCHIUM - most inferior of the 3 the ‘sit bone’ PUBIS – most anterior of the 3 forms the symphysis

THE INNOMINATE FUNCTIONS: Support internal organs Changes in the human pelvis allow for bipedal locomotion

THE INNOMINATE Each innominate articulates with *sacrum (at the auricular surface) *one femur (at the acetabulum) *the other innominate (at pubic symph)

THE INNOMINATE – what to know The ilium: medially - Iliac crest – superior rim Iliac fossa – superior depression under rim ASIS and AIIS Arcuate line – midline inferior ridge Iliac tuberosity – posterior rugosity Auricular surface - posterior (art.w/ sacrum) Preauricular sulcus

THE INNOMINATE – what to know The ilium: laterally – Iliac crest Iliac pillar – ridge on midline of blade PSIS and PIIS Greater sciatic notch Acetabulum (actually the point where all three bones fuse together, art. w/femur)

THE INNOMINATE – what to know The ischium and pubis – medially Pubic ramus: anterior/superior, twists Pubic symphysis: most anterior point Ischiopubic ramus: flat Obturator foramen: big hole The ischium and pubis – laterally Ischial spine: most inferior/posterior Lesser sciatic notch: inferior Ischial tuberosity: very thick Pubic tubercle: anterior, above symph

THE INNOMINATE – L from R Orient ilium (crest and blade) superior Orient the pubic symphysis anteriorly and medially, ischium posterior and inferior The acetabulum is on the side of origin (lateral)

THE INNOMINATE – fusion ages Ischiopubic ramus; 5-8 years Acetabululm; 11-17 years Ischial tuberosity; 16-20 years Iliac crest; 17-23 years

THE INNOMINATE uses in forensics The pelvis is best for sex – due to changes in the pelvis for childbirth, there are numerous, easy to distinguish features that help differentiate males from females in both the PUBIS and the ILIUM ALSO, well developed methods for aging adults based on changes in the PUBIC SYMPHYSIS

THE INNOMINATE uses in forensics TO RECAP: SEX: PUBIS AND ILIUM AGE: FUSIONS, AURICULAR SURFACES, PUBIC SYMPHYSIS

The sacrum Large, wedge-shaped Composed of 5 sacral vertebrae – fused Articulates with L5, both innominates Characteristics Large bodies Reduced spinous processes

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The sacrum – need to know Posteriorly – Posterior sacral foramina Anteriorly Anterior sacral foramina Transverse line of fusion Superiorly Sacral promontory (sup/ant): central, superior border of S1 Superior articular facets: articulation of L5-S1 Spinal canal Ala (wings) Laterally Auricular surface Spinous processes

The sacrum – uses in forensics Male vs female Males sacrum curved Females sacrum straight (WHY?) Age Transverse line between S1 – S2 closes mid twenties

The coccyx Coccyx – group of fused bones vs coccygeal vertebra (individual bone) Usually 4 segments fused – variation 3-5 CV1 had transverse processes and horns (cornua) CV2+ are variable, small, frequently lost Typically all fuse together and frequently to sacrum

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