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Forensic Anatomy > WEEK 2- sex estimation in adults > Flashcards

WEEK 2- sex estimation in adults Flashcards

1
Q

What is biological sex?

A

Based on reproductive system
phenotypical expression of chromosome X or Y
caused by natural and sexual selection over evolutionary time

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2
Q

What Is gender?

A

Social construct/ concept
social structuring based on various factors including biological sex differences
reflects different political, economic, social and reproductive strategies

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3
Q

what are the key difference between male and females?

A
  1. Skeletal consequences of sexual dimorphism
  2. Size- adult males are often larger than females- males have more muscle attachments, can look at molar teeth
  3. Robusticity- males greater muscle bulk, stronger muscle attachments and larger joint surfaces
  4. Reproduction- the female pelvis is adapted for childbirth and my show evidence of parturition trauma
  5. Bone chemistry- sex differences in bone mineral content, trace element levels, dietary stable isotopes and DNA
  6. Behaviour- culturally induced sex differences in patterns of trauma, body modification and stress markers (tattoo- soft tissue, but cutting teeth into pattern may assist in identifying)
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4
Q

What is estimation of sex of a skeleton influenced by?

A

Age, population affinities and preservation

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5
Q

Accuracy of sexing the skeleton by different bones?

A
  • 90-95% for whole skeletons
  • 90% pelvis
  • 80% cranium
  • 70% long bones
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6
Q

Accuracy and bias estimation

A

Direct tests= effectiveness in classifying known sex individuals
Indirect tests= calculation of the sex ratio in a representative sample of skeletons

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7
Q

Main diagnostic traits are

A

Skull and pelvis

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8
Q

What are most of the traits form?

A

Most traits relate to either muscle attachment of child birth- muscles of mastication leave marks on males

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9
Q

How many diagnostic traits are there for the skull?

A

25

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10
Q

Main diagnostic traits

A
  1. nuchal crest- Female= smooth, male= ridged
  2. mastoid process- female= small and inflected, male- large and vertical
  3. orbital margin- female= circular and sharp, male= quadrangular and rounded
  4. Supra-orbital ridge/glabella, Female= slight, male= prominent
  5. mental eminence, female= small and rounded, male= large and projecting
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11
Q

What are the osteological catergories?

A 
Definite female- F 
possible female- f?
indeterminate- ?
possible male - m?
definite male- M
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12
Q

What do sex diagnostic traits of skull depend on?

A

Ethnicity
European different from Asian
example- mastoid process in Asians not as pronounced

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13
Q

Overall difference in male and female pelvis

A

Female- shallower, broader and more rectangular in anterior view, with wider subpubic space

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14
Q

Which parts of the pelvis can be measured?

A

1, smaller acetabulum

  1. medial extension of pubis
  2. triangular obturator foramen
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15
Q

How many sex diagnostic traits are there for the pelvis?

A 
25 
main ones:
pubic inlet- broad and oval in F
greater sciatic notch- U shaped, obtuse >60 F
sub pubic angle- Broad and U shaped F
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16
Q

Where are sex difference of the pelvis found?

A

Anterior aspect of the pubic symphysis and the medial aspect of the inferior pubic ramus

17
Q

When do the characteristics of the pelvis develop?

A

Late adolescence

reliable indicators of sex in several populations

18
Q

How can the femur determine sex?

A

Middle of the shaft

width measured

19
Q

Discriminant function analysis of hip bone

A 
DF= (25.15x A /P )/ (0.132 x I) - 31.84
A= acetabulum diameter
I= ischial length- upper acetabulum to lower margin of ischial tuberosity 
P= pubic length- upper margin of pubic symphysis to nearest point on rim of ac
20
Q

Results of DF

A 
NEG= female 
Pos= male
21
Q

Accuracy of the DF measurements?

A

98% Accuracy

22
Q

Measurements of the femur

A

Length, prox and head diameter
femur mids diameter
talus length
clavicle diameter

23
Q

Discriminant analysis

A

linear combinations of multiple measurements provide evidence for discrimination between defined groups
different measurements are weighted by coefficients then all weighted measurements are summed and given discriminant score

24
Q

Potential skeletal indicators of pregnancy

A
  • Discrete zones of cortical resorption (pits) on the hip bone, particular along the posterior region of the pubic symphysis
  • extended pubic tubercle (attachment of inguinal ligament and rectus abdominal muscle)
  • scarring where ligaments torn or made in pitting into bone
25
Q

What can the pelvis say about birth?

A

If its been had

NOT how many times

26
Q

Prominent pubic tubercle

A

Pitting along the posterior (dorsal) margin of the pubic symphysis

27
Q

Sexing immature skeletons

A

Before puberty
no real way to tell
reliable skeletal sex difference emerge at puberty

28
Q

What influences sex diagnostic trait development

A

hormones

29
Q

Sexing kids using teeth

A

Permanent tooth crowns- M1 and M2 children with those teeth statistically (6-8 years)

30
Q

Sex diagnostic traits in children

A
  • mandibular symphysis
  • gonial angle on mandible
  • greater sciatic notch
  • iliac crest curvature
  • orbital margins
31
Q

Sex specific genetic material

A

Used to estimate well preserved sub adult skeletons

32
Q

Biomolecular methods of sex estimation

A

Amplification of amelogenin genes

  • small lengths of DNA are amplified with short 6bp differences detected between X and Y
  • these sequences are only present as single copies per chromosome
  • allelic dropout can also affect the accuracy of procedure, resulting in an XY individual being recorded as X
33
Q

Amplification of Y- repeat sequences

A
  • Y repeat are short sequence present in multiple copies within the y chromosome
  • presence of Y repeat DNA indicates a male, but absence of the sequence could result from failure of the method
34
Q

Method

A

Costly
Worth doing for small numbers
Pick out Y chromosome to say if its male but cant see if its female as it might but also might be an error

35
Q

Measurements of the humerus for sex

A

measure the head width and the bi-epicondular width

36
Q

Measuring the radius

A

Transverse width

head width

37
Q

Femur width

A

Head and bicondylar width

Forensic Anatomy (7 decks)

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