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                            DEPARTMENT OF ANATOMICAL SCIENCES

 

                                       AN321  - FORENSIC OSTEOLOGY

 

                          SEX DETERMINATION FROM THE SKELETON

 

                                                            Laboratory

 

 

 

OBJECTIVES

 

Once this practical class has been completed, the student should be capable of:-

 

 

            1. Identifying and describing the non-metrical morphological features that

               distinguish the adult male and female pelvis.

 

 

 

            2. Making a confident estimate of sex from the non-metrical morphological

               features of the isolated adult hip bone.

 

 

 

            3. Applying the technique of Suchey-Brooks to the sexing of the isolated

               adult pubic bone.

 

 

 

            4. Identifying and describing the non-metrical morphological features that

               distinguish the adult male and female cranium and mandible.

 

 

 

            5. Applying the technique of Larnach & Freedman (1964) to the sexing of the

               adult Aboriginal Cranium.

 

 

 

            6. Applying the metrical method of Giles and Elliot (1963) as adapted by

               Brown (1981) to the sexing of the Aboriginal cranium.

 

 

 

            7. Identifying and describing the non-metrical morphological features that

                distinguish the adult male and female sacrum.

 


TEACHING MATERIALS

 

 

HANDOUTS

 

            Laboratory class notes.

            Diagrams of sexual features of the adult male and female pelvis and cranium.

            The Larnach & Freedman (1964) descriptive list of 7 sexual features of the

            adult Aboriginal cranium.

            Notes on the Giles & Elliot (1962) metrical method of sexual attribution.

            P Brown's (1981) modification of the Giles and Elliot method for sex

            determination of Aboriginal crania.

 

 

SPECIMENS and DEMONSTRATIONS

 

            Articulated male and female pelves.

            Isolated male and female hip bones.

            Contrasting male and female crania (Caucasian).

            Examples of male and female Aboriginal crania.

            Aboriginal crania for sex determination

 

 

EQUIPMENT

 

            sliding calipers.

            spreading calipers.

            coordinate calipers.

            calculator.

 

            Suchey-Brooks teaching set of pubic symphysial casts for sex determination

            Standard casts for sexual determination from the cranium (Larnach &

            Freedman 1964).


EXERCISE 1.

 

 

VISUAL SEX DETERMINATION FROM THE ARTICULATED PELVIS

 

Comparison of a typical adult male and female articulated pelvis.

 

 

 

 

Compared with the female, the articulated adult male pelvis has many of the following distinguishing morphological features:

 

 

            a)         a greater overall height.

            b)         a narrower pelvic cavity.

            c)         a more sinuous (curved) iliac crest.

            d)         a higher, deeper and less broad iliac fossa.

            e)         a heart shaped pelvic brim (android) rather than an oval shape

                        (gynecoid).

            f)          an acute subpubic angle (often <80 degrees) rather than a right or

                        obtuse angle.

 

 

 

 

 

EXAMINE the demonstration articulated pelves supplied, CHECK for each of the above criteria, and ENTER their presence (   ) or absence ( - ) into the table below

 

 

            ---------------------------------------------------------------------------------------------

            Specimen ID   :           Morphological Criterion                    : Allocated Sex

                 No. :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :

 

 

EXERCISE 2.

           

 

VISUAL SEX DETERMINATION FROM THE ISOLATED HIP BONE

 

 

 

Compared with the male, the isolated adult female hip bone has many of the following distinguishing morphological features:

 

            a)         an L-shaped greater sciatic notch (J-shaped in the male).

            b)         a well marked preauricular sulcus (absent in the male).

            c)         an auricular surface that is elevated above the adjacent bone

                        (coplanar in the male).

            d)         a thin concave (recurved) inferior pubic ramus (thick and convex

                        in the male).

            e)         an estimated subpubic angle of 90 degrees or greater (usually <80

                        degrees in the male).

            f)          parturition pitting on the dorsum of the pubis (absent in the male).

 

 

 

EXAMINE each of the unknown isolated hip bones supplied, and RECORD in the table below, the presence (   ) or absence ( - ) of each of the above criteria.

Use the diagrams supplied to assist.

 

 

From your observations, DETERMINE THE SEX of each hip bone.

 

            ---------------------------------------------------------------------------------------------

            Specimen ID   :           Morphological Criterion                    : Allocated Sex

                 No  :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :

            ---------------------------------------------------------------------------------------------


EXERCISE 3.

 

 

VISUAL SEX DETERMINATION FROM THE OS PUBIS

The Suchey Brooks Method

 

Familiarisation with the Technique.

 

 

 

Use the teaching set of pubic symphysial casts supplied.

 

 

1.  Examine and compare CAST III (typical male) and CAST IX (typical female).

 

            NOTE:

 

            . the ventral arc; prominent in the female, absent in the male.

 

            . the subpubic concavity; the female shows a lateral recurve, the male lacks a

              lateral recurve.

 

            . the wide subpubic angle in the female; a narrow angle in the male.

 

            . the medial aspect of the inferior pubic ramus is narrow and often with a

              distinct ridge in the female; in the male it is wide and blunt.

 

            . the body of the pubic bone is wide and rectangular in the female; narrower

              and triangular in the male.

 

            . the female often shows large irregular scooped out pits on the dorsal aspect.

 

 

 

2.  Examine the pattern in CAST VII (16y female) and CAST VIII (16y male).

 

            Sex is difficult to determine in the skeletal remains of teenagers.

 

            The ventral arc is usually absent or in its precursor condition.

 

            By age 16 however the female pubic bone has usually broadened to the extent

            that sex differentiation is possible from this trait alone.


EXERCISE 3.

 

 

VISUAL SEX DETERMINATION FROM THE OS PUBIS

The Suchey Brooks Method (cont.)

 

 

 

3.  Recognition of the developing ventral arc in teenage females - CASTS I and VI.

 

            CAST I (20y female). This shows a precursor condition of the ventral arc.         There is a faint line where the arc will develop.

 

            This precursor state may be seen in females from 14-30yrs. It commonly

            occurs in the teens and early twenties. Recognition of the ventral arc in its

            precursor condition, is an aid to the determination of sex in young individuals.

 

 

 

 

4.  Further examination of the male pubic bone.

 

            CAST V. Most males lack a ventral arc. In some males however, a line may

            appear but it usually parallels the ventral border and should not be confused

            with the ventral arc.

 

            CAST IV. Rarely (in 4% of males) a ventral arc will be present as in this

            male.

 

            Other features of the bone will indicate that it is male.


EXERCISE 4.

 

 

VISUAL SEX DETERMINATION FROM THE ADULT CRANIUM

 

 

 

Compared with the female, the adult male cranium is characterised by the following morphological features:

 

            a)         More prominent superciliary (brow) ridges.

            b)         A duller (less sharp) superolateral orbital margin.

            c)         A moderate to marked tubercle on the zygomatic (malar) bone.

            d)         Larger mastoid processes.

            e)         Well marked temporal lines (temporal muscle markings).

            f)          A prominent supramastoid crest.

            g)         Prominent nuchal markings on the occipital bone (neck muscle

                        markings).

 

EXAMINE the demonstration set of typical adult male and female crania and FAMILIARISE yourself with the above morphological features. Use the diagrams supplied to assist.

 

Now EXAMINE each of the unknown crania supplied, and RECORD in the table

below, the presence (   ) or absence ( - ) of each of the criteria listed above.

 

From your observations, DETERMINE THE SEX of each cranium.

 

            ----------------------------------------------------------------------------------------------

            Specimen ID   :                   Morphological Criterion                        : Allocated

                 No  :           :           :           :           :           :           :           :    Sex

            ----------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :           :

            ----------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :           :

            ----------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :           :

            ----------------------------------------------------------------------------------------------

                                    :           :           :           :           :           :           :           :

                                    :           :           :           :           :           :           :           :

            ----------------------------------------------------------------------------------------------


EXERCISE 5.

 

 

VISUAL SEX DETERMINATION FROM THE ABORIGINAL CRANIUM

THE LARNACH & FREEDMAN (1964) METHOD

 

Familiarisation with the Technique

 

 

 

            In this method seven morphological features of the cranium are used, 5 visual     and       2 metrical. (See attached list & descriptions)

 

 

            The 5 visual criteria use casts or graphic scales that define the standards for       size.

 

 

            The 2 metrical criteria are based on measurements of the mastoid process and the

            palate, and are calculated according to the formulae supplied by Larnach &

            Freedman (1964).

 

 

            Each criterion is given a grade value of 1, 2 or 3 depending on its size.

            When applied to Aboriginal crania from the Murray Valley Black by Brown

            (1981), the two metrical criteria required redefinition of their grade values to give

            greater accuracy in sex determination.

 

 

            The grade values (scores) for each criterion are then summated and the total

            score compared with the sectioning point between male and female which in

            this study was found to be 11/12.

 

 

            This method has a reported accuracy of 90-95% when applied to Coastal NSW           Aboriginal crania.


EXERCISE 6.

 

 

VISUAL SEX DETERMINATION FROM THE ABORIGINAL CRANIUM

THE LARNACH & FREEDMAN (1964) METHOD

 

Application of the Technique

 

 

 

REFER to the pages of Larnach & Freedman (1964) (attached).

 

EXAMINE each of the unknown Aboriginal crania supplied and ASSESS & RECORD the value for each of the 7 criteria in the table below.

Then DETERMINE & RECORD the sex.

 

 

--------------------------------------------------------------------------------------------------------

  Cranium        :                       Criterion Score                                   :Total  : SEX  :

     ID               :           :           :           :           :           :           :           :Score :           :

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                        :           :           :           :           :           :           :           :           :           :

                        :           :           :           :           :           :           :           :           :           :

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                        :           :           :           :           :           :           :           :           :           :

                        :           :           :           :           :           :           :           :           :           :

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                        :           :           :           :           :           :           :           :           :           :

                        :           :           :           :           :           :           :           :           :           :

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                        :           :           :           :           :           :           :           :           :           :

                        :           :           :           :           :           :           :           :           :           :

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EXERCISE 7.

 

 

METRICAL SEX DETERMINATION FROM THE ADULT CRANIUM

THE DISCRIMINANT FUNCTION METHOD OF GILES & ELLIOT (1963)

 

 

This has been adapted to sex determination of Aboriginal Crania from the Murray River Valley by P. Brown (1981).

 

Read page 54 of Brown's 1981 publication (attached).

 

Pick an apparent male and female Aboriginal cranium (on visual criteria) from the pool of crania provided and carry out the nine measurements (in mm) as used by Brown (1981) in his application of the Giles and Elliot's discriminant functions to the Murray Valley material.

 

The appropriate measurements and weightings are:

 

            1. Cranial Length          (4.692)                         2. Cranial Breadth        (1.000)

 

            3. Basion-bregmatic Height (8.769)                  4. Basion-nasion length (4.615)

 

            5. Bizygomatic breadth (21.308)                       6. Basion-prosthion length (-4.385)

 

            7. Nasion-prosthion height (7.385)                    8. Mastoid length (21.077)

 

 

Multiply each measurement by its weighting (in brackets) and add into the table below. Make sure you use the correct sign (plus or minus).

 

Sum the results and get the total score.

 

-------------------------------------------------------------------------------------------------------

  Cranium        :                    Weighted Parameter                            :Total  :SEX:

       ID             :           :           :           :           :           :           :           :Score :           :

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                        :           :           :           :           :           :           :           :           :           :

                        :           :           :           :           :           :           :           :           :           :

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                        :           :           :           :           :           :           :           :           :           :

                        :           :           :           :           :           :           :           :           :           :

-------------------------------------------------------------------------------------------------------

 

The section point calculated by Brown was 6041.16. A score greater than this is allocated a male sex and a lesser score is allocated a female sex.

 

How do your results measure up to your visual allocation of sex?

 

REFERENCES

 

 

Brown P 1981 Sex Determination of Aboriginal Crania from the Murray River Valley: A Reassessment of the Larnach and Freedman Technique. Archaeology in Oceania, 16(1):53-63.

 

Giles E & O Elliot 1963 Sex Determination by Discriminant Function Analysis of Crania. American Journal of Physical Anthropology, 21:53-68.

 

Larnach SL & L Freedman 1964  Sex Determination of Aboriginal Crania from Coastal New South Wales. Records of the Australian Museum, 26:295-308.

 

Stewart TD  1979. Essentials of Forensic Anthropology. CC Thomas Publishers