Exam 2: Skeletal Analysis

Sexual Dimorphism

-ability to differentiate between male and female skeletons -expression of phenotypic differences between males and females of same species

Age of majority

-age to be legally considered an adult

juvenile/subadult

-ages during the growth and development process including embryonic, fetal, infant, child, and adolescent period

adult

-ages occurring during mature, degenerative stage of skeletal change

teeth at time of birth

-all deciduous teeth and first permanent molar have begun to mineralize

age 3

-all deciduous teeth have erupted with complete root formation

appearance and fusion of certain primary ossification centers

-also useful in estimating juvenile age -correlated with age -cranium

Non Metric sex estimation based off skull

-analysis of overall shape and relative size of certain cranial and mandibular features

What should you also consider when estimation sex?

-ancestry, because sexual dimorphism varies across populations

why is dentition more accurate?

-appears to be under stronger genetic control -bone development more susceptible to environmental influences

how does the adult aging process occur?

-as consequence of evolutionary history and result of maintenance of bodily homeostasis

most common aging subadult dentition method

-assessment of dental development stages

when does the neonatal line form?

-at or soon after birth

Adult skeleton

-begins to sow degenerative changes -attempt to maintain homeostasis -changes influences by extrinsic factors

when do most epipyses unite?

-between 10 and 25 years old

when does the third molar crown?

-between 6 and 12

What type of decision is sex estimation?

-binary decision

Parturition

-childbirth

estimating sex in subadults

-considered inadvisable -validated methods are unavailable

Metric methods

-considered to be more objective

what does skeletal age estimation involve?

-correlating biological age with chronological age

Age and ancestry

-craniofacial characteristics related to ancestry absent or less pronounced in subadults compared to adults

dental development methods

-determine developmental stage of each individual tooth, including crown and root -in reference to illustrated development stages -timing is different for each tooth position

Female ilium

-developed preauricular sulcus present

osteological method for determining age

-diaphyseal grwoth -strong linear relationship between diaphyseal length and age

What do skeletal differences result from?

-different bio mechanical functions of joints for efficiency in locomotion and parturition

Second most accurate visual to estimate sex

-dimensions of various long bones of postcranial skeleton

trajectory effect

-discrepancy between biological age and chronological age -widens as people get older

early epiphyseal union

-distinct line is visible between two component -tends to obliterate through remodeling with age

Femur

-due to wider hips, angle at which femur meets tibia at knee is greater in females

when do the permanent anterior teeth and first molars begin to mineralize?

-during first year of life

when should skeletal age be determined?

-early in examination process -ability to estimate other biological parameters, sex/ancestry/stature, may depend on category

Neotenous/pedomorphic

-females are more like this -retaining more juvenile-like traits anatomically, including skeletally

dental development variation

-females tend to be more advanced in dental development -tooth calcification rates vary between populations

sequence of tooth eruption

-follows particular pattern correlated with age

Non Metric

-for sex estimation, more useful -visual assessment of pelvis is most accurate method -visual, qualitative assessment of skeletal features that tend to vary between males and females

discriminant function analysis

-for skull -first applied in 1960s -correctly estimated sex at rate of 85%

subadult age estimation, teeth

-formation, mineralization and eruption of deciduous and permanent dentition -highly correlated with chronological age -most accurate

neonatal line

-formed in all deciduous teeth -often on first permanent molar -caused by stresses of birthing; can indicate if born alive or stillborn

influences on sexual dimorphism

-genetic factors -nutrition -health status

lateral angle of internal acoustic meatus

-greater in females

pubic symphysis of young people

-horizontally-oriented ridges and furrows -symphyseal face lacks distinctive border; no defined edge where it separated from ischial and pubic rami

what are the last epiphyses to fuse?

-iliac crest -sternal end of clavicle

Costal cartilage calcification

-in females, more central ossification pattern -in males, pattern is more marginal -accuracy is age dependent

obturator foramen

-in females, more triangular -in males, more oval

Sciatic notch

-in females, wider -in males, narrow -males sometimes of wide notch, but females never have narrow

What happens to bones that are subjected to greater mechanical loading and stress?

-increase in cortical area

most reliable metric method

-involve dimensions of long bones of postcranial skeleton

The Phenice Method

-involves evaluation of three traits of the os pubis -around 96% accuracy

Metric Analysis

-involves measuring maximum or minimum dimensions or taking measurements based on osteological landmarks to quantitatively evaluate size and shape differences between males and females

categories of skeletal age

-juvenile/subadult -adult

Human males

-larger -more robustly built -height, weight, breadth -bones are longer, thicker, more prominent muscle attachments

Male skull

-larger -more rugged and robust

tooth size

-larger in males

chronological age

-length of time a person has been alive -measured by time

Metric methods for sex estimation from skull are considered what, compared to postcranial skeleton?

-less reliable -still widely applied and useful though

how does postcranial long bone growth occur?

-longitudinally and appositionally

Most reliable non metric skull features

-mastoid size -supraorbital ridge size -general size and architecture -rugosity of supremeatal and supramastoid crest -size and shape of nasal aperture -gonial angle

the more extensively studied and commonly employed long bone measurements

-maximum diameter of femoral head -femoral neck diameter -vertical diameter of humeral head

Third most accurate visual to estimate sex

-methods involving the skull

Sexual dimorphism relates to differences in what?

-morphology, which means size and shape

Locomotion

-movement

are the epiphyses well preserved?

-no -due to fragility

are biological and chronological age perfectly correlated?

-no -skeletal aging process is variable between individuals

Methods to estimate sex

-non metric (macroscopic or visual) -metric analysis

Assessments in Non Metric analysis

-observations of the degree of expression of certain traits -determination of presence or absence of particular feature

subadult age estimation, bones

-ossification, long bone growth, epiphyseal union

Most sexually dimorphic region of the skeleton

-pelvis -due to childbirth function

biological age

-physiological age

ages 2-4

-premolars and second molars

Rhomboid fossa

-presence more common in males

septal aperture

-present in females

Sub-pubic concavity of the ischiopubic ramus

-present in females -absent in males

Ventral arc

-present in females -absent in males

Suprascapular notch

-present in males -absent in females

epiphyseal union

-primary and secondary ossification centers unite

how is the assessment of appearance and union of ossification centers accomplished for intact bodies or living people?

-radiography

Do humans display high or low sexual dimorphism?

-relatively little sexual dimorphism

subadult age estimation

-relies on predictable processes of growth and development of bones teeth -process proceeds at rapid pace from birth to first year of life; rapidly declines from infancy to childhood

Many sexually dimorphic traits are what?

-secondary sexual characteristics that develop during puberty

Medial aspect of the ischiopubic ramus

-sharp and narrow in females -dull and wide in males

when does dental development begin?

-sixth fetal week -not complete until early adulthood

What are the differences related to?

-size -architecture

Female skull

-smaller -smoother

Age and sex

-some indicators can be absent or underdeveloped until after puberty -in females, muscle attachment sites may become more robust with advancing age

What other analyses are sex-specific?

-stature -age

stature and age

-stature increases during growth and development -decreases with advanced adult age due to degenerative changes in vertebral column

What does estimating sex from skeletal remains involve?

-the identification and evaluation of characteristics that tend to show differences between male and female skeletons -variable expressed

what is the best documented skeletal area for adult age estimation?

-the pubic symphysis

What happens due to little sexual dimorphism?

-there is considerable overlap between males and females

how is age estimation from a skeleton possible?

-through comprehensive understanding of the nature, sequence and timing of skeletal changes across lifespan

tooth eruption

-tooth advances from alveolar crypt, where it develops, to its functional occlusal position in oral cavity

skeletal age estimation is what type of process?

-transformative -translate descriptive skeletal age indicators into chronological age -introduces error

suchey-brooks method

-used for estimating age from pubic symphysis -6 phase system with detailed morphological descriptions -focuses on changing features found on and surrounding face of pubic symphysis

when does diaphyseal growth become unuseful?

-useful until epiphyses begin to fuse with the diaphysis; at around 10

three phenice traits

-ventral arc -sub-pubic concavity of ischiopubic ramus -medial aspect of the ischiopubic ramus

when is skeletal growth and development considered complete?

-when all permanent teeth have erupted -all epiphyses have fused

Female pelvis

-wider -a pelvic inlet -shorter and broader -widely configures pelvic inlet and wider sub-pubic angle

is there a strong correlation between chronological age and morphology of ossification centers?

-yes

is the sequence of epiphyseal union correlated with age?

-yes, chronological age