Forensic Anthropology Exam 2


Terms in this set (...)

Stages of decomposition
1) Fresh, within 24 hours

2) Early, within 2 weeks

3) Advanced decomposition, continuous decomposition

4) Skeletonization, when the skeleton appears

5) Extreme decomposition, when the skeleton starts to decompos
Factors affecting decomposition stages
Body composition
- Large vs. small body

Cause and manner of death
- Open wounds vs. no open wounds

Depositional context
- Burial, dump, etc.

Environmental conditions
- Weather, climate, animals, insects, etc.
Time intervals
1) Minutes to hours
2) Hours to one day
3) Weeks to months
4) Months to years
5) Years to eons
Minutes to hours (1)
Enzymatic changes, cellular respiration ceases

- Autolysis, Putrefaction

Both internal processes (autolysis and putrefaction) are sufficient even in the absence of insects and carnivores to reduce a body to bones
Early biochemical process of decomposition

Cell death destroys cellular integrity, results in widespread tissue necrosis

This is basically cell death
A byproduct of autolysis

The consumption of body tissues though proliferation of bacteria

The bacteria explodes once you die

Decomposition becomes observable at the gross level during putrefaction

Tissues become paler in color

Breakdown of cells between dermis/epidermis results in skin slippage
Hours to one day (2)
Algor mortis, livor mortis, rigor mortis
Algor mortis
Cooling of the body to ambient temperatures

During life, core body temperature is around 98.6*F

Once metabolic pathways are disrupted via death, body begins to cool gradually, then rapidly, until it achieves equilibrium with ambient temps

Bodies do not cool at consistent rates

Temperature drops slowly, creating a plateau, then increases

Easily influenced by context (clothing), setting (outside), biology (sick), demography (older), etc.
Livor mortis
Gravitational pooling of blood

Results in discoloration where body experiences gravitational pooling (i.e. feet in hanging person) - when the blood starts to settle in specific parts of the body closer to the ground

Begins about 2 hours after death, becomes fixed 8-12 hours postmortem

Once fixed, no longer useful in estimating PMI

Fixed blood is quagilated blood, not flowing

If you press down on livor mortis body, it will go pale and the blood will not return to that place and will just sink
Rigor mortis
Muscle stiffening

During decay process, muscle fibers stiffen/lock into place

With time, muscle fibers degrade from anchor points, gradually causing rigor mortis to dissipate

General rule - begins 1-2 hours in the jaw and moves downwards, with complete stiffness at about 12 hours postmortem

It will dissipate over the next 12+ hour period
Initial decomposition
The rate depends on conditions of body and environment, usually begins 2-3 days in unrefrigerated corpse

- Skin slippage, Discoloration, Bloating
Skin slippage
Early decomposition (glove formation)

It's like dipping your hand in Elmer's glue and stripping it off, that's what happen with skin slippage
Loss of epidermis and hair
Rupture of connective tissues causes, nails loosen

Hair typically starts to fall over around the 1-2 week postmortem

Where the hair mats will show you where the body originally decomposed if it has been moved
Also occurs in early decomposition

Initially, a green discoloration of abdominal wall due to proliferation of normal flora in the gut

Darker color often occurs in conjunction with bloating (usually 1 to 8 weeks)

The body typically starts to look pretty leathery

"Marbling" may occur
Occurs when internal bacterial colonize and decompose venous system

The decomposition of the veins

Early decomposition sign
Swelling of tissues during release of gasses

Generally appears at 2-8 days postmortem, especially in face

Bulging on tongue and eyes, and extrusion of feces

The gases are pushing out what is inside the body from the orifices

Frothing or foaming of blood from trachea

Post-bloat stage with rupture of abdominal cavity from gasses
Weeks to months (3)
Disarticulation, skeletonization - where the anthropologist comes in

- Liquefaction, Adipocere (saponification), Mummification, Skeletonization
Results as fat liquefies (especially in abdominal cavities)

Causes sagging of flesh, caving-in or abdominal cavity

Looks like puddles of tissues
Adipocere (saponification)
Is the formation of "grave wax" due to hydrogenation of lipids

Can occur in conjunction with liquefaction, skeletonization, mummification, or combination

Typically occurs in moist environments (caskets, clandestine burials, drowning victims)

It can last very long
Common in arid environments

Drying precedes or interrupts decomposition

Body moisture less than 50% (bacterial growth arrested)

Skin becomes hard and leathery, but underlying tissue can remain moist with a thick, jelly-like consistency
Accelerated or retarded by environment, animal and insect activity, and exposure (buried/not buried)

Initial occurrence in head and hands - less skin

Areas of trauma skeletonize faster

Timing is variable
- 3 days in Texas, 3 months in Tennessee, 3 years in Alaska
Months to years (4)
Wearing, burial, bioturbation

Extreme decomposition, where the bone starts to deteriorate

Two immediate effects: bleaching, exfoliation
Occurs to the bone typically around 9 months to 3 years

Fresh bones would have a more yellow, tan color not white
Of out layers of bone occurs 3+ years

Flakes will start to fall of the bone if it is picked up
Years to eons (5)
Variables that affect decomposition
1) Temperature, humidity, and access by insects
2) Burial/depth of burial
3) Water immersion
4) Carnivores/rodents
5) Trauma
6) Clothing
Temperature, humidity, and access by insects
- Hot weather accelerates liquefaction
- Cold slows decay
- High humidity increases insect activity and liquefaction
- Low humidity increases mummification
- Insects affect rates of decomposition
- Initially invade face and orifices
- Can reach body in seconds
Differential decomposition
Two people died in the same house but decomposed differently

One was in the basement which made it look really fresh

The other was upstairs where it was warmer and looked far more decomposed
Burial/depth of burial
Buried bodies decompose slower than surface bodies

Burial prevents access by insects/carnivores; greater than ~2 feet, insects and carnivores can't detect

Soft tissue decomposition depends on moisture of soil and presence of soil organism such as plant roots and bacteria; adiopocere occurs in wet soil

Survival of buried skeleton depends on the pH of soil and moisture content
Water immersion
Increases skin slippage, prevents mummification

Scavengers can be present in both salt and fresh water

Soft tissue decomposition often retarded, but exposed portions still attract insects and undergo same decomposition sequences

Human bodies will typically float legs, head down, arms face down, only back exposed

In water, decomposition rate of body depends on temperature, salinity, and bacterial load of water
- Temperature: warmer - faster
- Salinity: higher - slower
- Bacterial load: higher - faster

If body resurfaces, the exposed portion will be invaded by insects and decomp will progress rapidly

If body submerged for long periods of time, adiopocere formation can occur

May see destruction, abrasion, and perforation of facial bones due to rolling/scraping of cranium along bottom
Target soft tissues of face/hands, end of long bones

Increase decay rate

Disarticulation, loss of elements
Accelerates decomposition; more bacteria and fly access

More access, faster decomposition will occur - more scavenger and insect access
Protects body from sun, enables maggot activity

Can slow down decomposition but maggots however don't like the sun, so they protect them from it which can accelerate the process
Number of adult versus sub-adult bones
On average, every person has 206 bones

We are not born with all of those bones, we are born with about 800 fragments of bone
Consisted of 28 bones

The head including the jaw
The skull without the mandible
Cranial structure
- Frontal
- Parietal
- Temporal
- Occipital
Located as the forehead

- Coronal suture, sagittal suture, superciliary arch, temporal line
Coronal suture
Goes from side to side, where a crown would lie

Where the parietal and frontal attach
Superciliary arches
Where the eyebrows lie, brow ridges

Helpful when looking for sex estimation

Women have smoother ridges than men who have more of a protrusion
Temporal line
At the sides of the frontal, edges of your eyebrows

Where you feel the jaw muscles move
Located at the sides of the skull, in Latin it means "wall"

It continues the temporal line from the frontal

More heavy that line is, the more likely it is male
- Most predominant muscle markings are indicators of male
Sagittal line
The line where the two parietals meet, like an arrow

There are not always as fused as others

Not a reliable method to estimate age
Located where are ears and cheekbones are

Has the apparatus for our hearing, where the auditory canal is

It is a really thin bone

Very susceptible to getting bashed in, most sensitive part of the skull

Forms the side to side features

Squamosal suture
- Where the temporal attaches to the parietal
Very thick part of the skull, keystone to protecting the brain

- Nuchal line
- Foramen magnum
- External occipital protuberance
- Lambdoidal suture
Nuchal line
The neck muscles

More prominent in males
Foramen magnum
The big hole where our spinal cord connects to our brain
External occipital protuberance
The very back, the large bump
Lambdoidal suture
The triangular line that attaches to the parietal
Facial structure
- Maxilla
- Zygomatic
- Nasals
- Sphenoid
- Mandible
- Dentition (adult versus subadult)
- Hyoid
Pair of right and left bone of our nasal opening and where the teeth hook into

Major portion of the lower face

Attaches to the lower part of the frontal

Where the two pieces meet create the roof of your mouth

The lower side and baseline of the eye orbits

Attaches to the frontal and maxilla

Forms the eye orbit with the lower frontal and upper maxilla

Attaches to the temporal, very easy to break
Right and left pair, they sit on top of the maxilla

Very small bones, very susceptible to breakage

The top part of the nose
It connects to so many parts of the skull and is hard to determine orientation

Located right before the temporal (laterally), inside the eye orbits (frontal), right behind the maxilla - the roof of the mouth (inferior)

Has important soft tissue connections, it hold the pituitary gland
The jaw

The largest free flowing bone, it is not sutured to any bone

There is a cartilage that attaches the jaw to the cranium
20 deciduous (baby) teeth

32 permanent (adult) teeth

Maxillary - the top set
Mandibular - the bottom set
Small U-shaped bone that is in our throats

Where most of our tongue muscles attach to

The production of speech

Critical to forensic cases, fractures or breaks when someone is strangled

Sometimes they don't always fuse

Completely covered by soft tissue
Consisted of 24 separate vertebrae

Major functions of the vertebral column

House and protect the spinal cord

Attachment for pectoral and pelvic muscles

Motion and support for the skeleton

Transmit body weight in walking and standing
Cervical vertebrae (7) - "Breakfast"
Vertebrae in the neck (C1-C7)

First cervical vertebra (C1) - atlas

Second cervical vertebra (C2) - axis

C3-C7 continue through the neck
- As the get lower they start to look more like the next vertebrae
First cervical vertebra (C1)

Is the "atlas" and holds the globe of the skull

It articulates at the facet of the foramen magnum
Second cervical vertebra (C2)

Is the "axis" and permits head turning and tilting

Why our head has a range of motions

Where most of the muscles begin to attach for movement
Thoracic vertebrae (12) - "Lunch"
Vertebrae at the mid-back (T1-T12) - connect to the 12 ribs

Not a lot of differentiation between them

The ribs attach to the facets, the parts that protrude outward
Lumbar vertebrae (5) - "Dinner"
Vertebrae in the lower back (L1-L5)

Supports weight of entire spine, why so many spinal problems are in the lower back

Biggest and most massive of the vertebrae
What part of the spine is considered to have poor design?
the lumbar vertebrae

we have an S-curve
To determine a difference between thoracic and lumbar, turn to the side
Thoracic look like giraffes, lumbar look like moose
A triangular structure made up of five fused vertebral elements forming the posterior section of the pelvis

Attach to the pelvis "wings"
The tail bone, the terminal segments of the sacrum

Looks like a mini sacrum
Pelvis region
Innominates/Os coxa

- Acetabulum
- Greater siadic notch
the socket for the head of the femur to fit into

Common to have dislocations from this area
Greater siadic notch
An area that you can look at and determine sex

Wide notch, women - narrow notch, men
What region is rich in sex estimation because of the distinctive architectural features as well as age estimation?
the pelvis
Thoracic Cage
Unit of bones that forms a cage to protect the lungs and other internal organs

- Sternum
- Ribs
- Clavicle
- Scapula
- Humerus
- Radius & Ulna
- Carpal
- Hand phalanges
Known as the breast bone
They are not moveable but are able to maneuver, some give to allow breathing for the lungs

There are 12 sets of ribs (24 in total)

The first 10 rib sets connect with cartilage to the sternum and the last 2 are just free floating ribs
Forms the housing for our arms

Great for young adult age estimation
- Under the age of 24, the fusion is still not complete

They will have an attachment point at the scapula
They are a right and left pair

Triangular shape, wings on the back - shoulder blades

The joint surface isn't adaptive for everything we need to do
Structurally very strong, an attachment site for the deltoid, good for sex estimation

At birth, it has about 8 fragments that will fuse together
is the outer bone, lateral - allow you to radiate (rotate)

They are both able to pivot and adjust to allow flexibility

Is part of the forearm, they do not cross each other and they are individual from each other
is the inner bone, medial - works like a pendulum, it hooks into the faccia

They are both able to pivot and adjust to allow flexibility

Is part of the forearm, they do not cross each other and they are individual from each other
There are 8 carpals in each hand

This is the wrist region
This is the palm of our hand, connecting carpals and the hand phalanges
Hand phalanges
There are 14 in each hand

This is our fingers

The reason for the number is that each finger has three bones except the thumb which has two
- Femur
- Patella
- Tibia
- Fibula
- Tarsals
- Metatarsals
- Foot phalanges
The most difficult bone to break, very sturdy

The bone in your thigh

Muscle markings can help in sex estimation
Largest sesamoid - a free floating bone

The kneecap

It rides on a sheath above the end of the femur

High activity results in damage and wear
It is weight bearing, it is a connection point from our knee to our feet

Good place to look for age estimation due to fusing

Very susceptible to breakage and fracture
It is the other bone alongside the tibia

Not weight bearing, does function to strengthen the tibia

It is the skinny bone more toward the internal side of the calf

That bone that juts out of the ankle on the interior, that is the end of the fibula
The foot ankle bone, just like the carpals

We have 7 of them
Make up the top of your foot
Foot phalanges
Just like the hand, three in each toe except the big toe that only has two