How to Differentiate a Male Pelvis from a Female Pelvis

Sex determination only by looking at the pelvis plays a major role in forensic anthropology. It is very easy to differentiate a male pelvis from a female pelvis as female pelvis has developed special features for child bearing. Following features are used in differentiating male and female pelvises.

	Female	Male
General Built	Thin	Thick
Weight	Light	Weight
Greater Pelvis	Shallow	Deep
Lesser Pelvis	Wide, shallow, cylindrical	Narrow, deep
Pelvic Inlet	Oval shape	Kidney Shape
Pelvic Outlet	Wider	Smaller
Pubic Arch	>800	<700

 Flesh and Bone: An Introduction to Forensic Anthropology 

Introduction to Forensic Anthropology (4th Edition) (Pearson Custom Anthropology) 

Bones: A Forensic Detective's Casebook 

The Human Skeleton (Forensic Anthropology): An overview

·         

·         Adult skeleton consists of 206 bones.

Importance in Forensic Anthropology

·         To differentiate it from other mammals.

·         To identify the person – age, sex etc.

01.  The Cranium

-          Consists of 27 bones.

o   Paired

o   Single – frontal

            Occipital

            Sphenoid

            Ethmoid

            Vomer

-          Important in Forensic Medicine in identification of sex. This is done by using two methods. They are,

o   Morphological

§  Overall size

§  Supraorbital development

§  Forehead shape

o   Metrical

§  Linear combination of number of a number of cranial dimensions

§  Discriminant functional analysis

02.  The Mandible

-          Formed to a single bone by fusing at the midline, by the age of 12 months.

03.  The Scapula

-          Consists of,

o   Dorsal and costal surface

o   Spine, acromion and coracoid process

o   Glenoid cavity

04.  The Clavicle

-          Epiphysial union

o   At sternal end – 25-28 years

o   At acromial end – 19-20 years

05.  The Sternum

-          Poorly preserved in forensic situations.

06.  The Ribs

-          Tend to decay faster

07.  The Humerus

-          Ossification occurs at 8 different centers.

o   In the shaft – proximal epiphysis – 19.5-20.5 years

         Distal epiphysis – 14-15 years

o   Greater tubercle

o   Lesser tubercle

o   Capitulum

o   Medial part of the trochlea

o   Each of epicondyles

-          Errors of estimation of stature from humerus are greater than the errors from the other long bones.

08.  The radius

-          Epiphysial union of the head of the radius – 14-15 years.

-          Epiphysial union of the distal radius – 18-19 years.

09.  The Ulna

- Epiphysial union of the proximal ulna – 14.5-15.5 years.

- Epiphysial union of the distal ulna – 18-19 years.

     08.  Bones of the Hand

- 26 bones

·         7 carpal bones

·         5 metacarpals

·         14 phalanges

- Each carpal bone ossifies from a single center.

- Capitate ossifies first and the lunate last.

- In females, ossification is completed by 12 years of age.

- Metacarpals ossify from two centers, primary and secondary.

-          Primary center - in the shaft.

-          Secondary center – in the proximal end of the metacarpal 1 and distal ends of metacarpals 2 to 5.

- Epiphysial union in metacarpals is completed by the age of 15-16 years.

- Metacarpals are used to find the stature and the sex.

10.  The Spinal Column

-           24 vertebra

-          Following can be used to identify cervical vertebrae.

o   Small size.

o   Presence of transverse processes, which are perforated by a foramen.

o   Atlas – has large vertebral foramen and does not have a body.

o   Axis – has a prominent process, the odontoid process.

-          Following are used to identify 12 thoracic vertebrae.

o   Each has costal facets for articulation with the ribs.

o   First 10 vertebrae have additional facets in their transverse processes for the articulation with the tubercles of the ribs.

-          Following are used to identify 5 lumbar vertebrae.

o   Broad bodies.

o   Triangular shaped vertebral foramen.

-          The Sacrum

o   Formed by the fusion of the five sacral vertebrae.

o   Important in sex determination, age estimation and parturition.

11.  The Iliac Bones

-          Consists of three parts, Ilium, ischium, and the pubic bone. They are separated in the infants.

-          They unite during the pubertal growth spurt.

-          Entire union is completed at by the age of 23 years.

-          Plays a main role in sex determination.

12.  The Femur

-          Has five ossification centers.

o   In the shaft

o   In the head

o   Greater trochanter

o   Lesser trochanter

o   At the distal end

-          Epiphysial union is completed by the age of 17-18.5 years.

-          Distal epiphysis closes last.

-          Used in stature estimation, sex and race determination.

-          Stature estimation from the femur is less erroneous than from other bones.

-          Can be used to determine the geographical origin.

13.  The Tibia

-          Ossifies from three centers, in shaft and in both ends.

-          Epiphysial closure at proximal end occurs at the age of 17.5-18.5 years.  

-          Epiphysial closure at distal end occurs at the age of 15.5-16.5 years.  

-           

14.  The fibula

-          Ossifies from three centers, in shaft and in both ends.

-          Epiphysial closure at proximal end occurs at the age of 17.5-18.5 years.  

-          Epiphysial closure at distal end occurs at the age of 15.5-16.5 years.  

-          Can be used to determine the geographical origin.

15.  Bones of the foot

-          Made of 25 bones.

o   6 tarsal bones.

o   5 metatarsal bones.

o   14 phalanges.

How to Identify Firearm Injuries

Before going in to identification of firearm injuries, one should have a clear idea about the types of firearms present. They are briefly classified by the following graph.

Smooth bore weapons include shot guns and pallets are used in those kinds of weapons. The most common smooth bore weapon is the shot gun. The rifled weapons use bullets. The rifled weapons have parallel spiral projecting ridges and therefore print a unique mark on the bullet. There are three main kinds of rifled weapons and they are,

1.      Revolver

2.      Rifle

3.      Pistol

As mentioned above different kind of weapons have there own characteristics and therefore, the injuries caused by these weapons also have their own unique features.

Characteristics of Shot Gun wounds

Mechanism: lead shot emerges from the muzzle as a solid mass and then progressively diverges in a cone shape as the distance from the weapon increases.

Other accompanied substances and forces:

1.      unburned powder

2.      flame

3.      smoke

4.      gases

5.      wads

6.      card

All these substances in accordance to the distance, contribute to the final appearance of the wound.

·         Entrance wound - neat circular hole, with or without abraded or bruised margins caused by the muzzle.

·         Round the wound – blackened due to smoke

                                               Burned due to flame

·         Gases – can cause lacerations when the gun is fired while the muzzle is in contact with the skin tightly and when there is an underlying bone.

Characteristics of Wounds Caused by Rifled weapons

·         Entrance wound - neat round holes approx 310 mm in diameter

·         Margins - smooth and regular and bordered by an even zone of creamy pink or pinkish red abrasion.

·         Exit wound - be larger than entrance wounds

         Irregular lacerations with everted, unabraded, and unbruised margins

How to know whether an Injury is caused by him/herself or by someone else

Some people injure themselves for various reasons. Many of them cut themselves but biting, scratching and various other methods of injuring are also present. This could be due to many reasons.

·        Some psychiatric illnesses – Injuring (cutting) themselves could be due to a psychiatric problem which needs medical attention.

·        To blame someone else or take revenge – Some people injure themselves so they can blame it on someone else. This is done to take revenge.

·        To create an event that did not occur – This is done when they try to prove something that didn’t actually happened.

Even though some people injure themselves and pretend as someone else did, it is quiet easy to recognize a self-inflicted injury from the rest. Following characteristics of the wounds are helpful in recognizing self- inflicted injuries.

·        Site – the areas are self accessible areas. Therefore they are mostly found on the arms and less likely to be found on the back.

·        Size – The injuries are small in size.

·        Number – they are multiple in number.

·        The wound have a regular depth equal from the beginning to the end.

·        They are parallel to each other.

·        Injuries are most present on the non dominant side of the person. For example if the person is right handed, the injuries will be more on the right side of the body.

·        If the cause is a psychiatric illness there may be a history of abnormal behavior.

Injuries

•         Injuries

•         Abrasions

•         Contusions

•         Lacerations

•         Cut

•         Slash Cut

•         Chop

•         Incised Wounds

•         Fire Arm

In abrasions only the superficial layers of the skin are damaged and therefore, they heal with no scaring. In laceration the full thickness of the skin is disrupted and therefore, leaves a scar.

Colour Change in a Contusion

•         Red

•         Blue -

•         Purple

•         Brown Green

•         Yellow - >18 hours old

What are tramline contusions?

Tramline contusions are bruises which occur from beating from a baton like instrument. When a person is hit from a baton, the skin is compressed. The central part of this area is compressed while the edges are stretched. This causes the blood vessels at the edges to rupture. As a result of compression the central areas lack blood and therefore, appear pale. Blood leaves from the damaged vessels at the edge and therefore, those areas appear bruised. The final outcome is a pale area outlined by two narrow parallel bands of bruising

Lacerations and cuts or incised wounds are sometimes hard to differentiate. In such situations, careful examination of the edges is important. The edges of the lacerations are irregular. Lacerations bleed less than cut injuries, because the blood vessels are crushed and thereby blocked. Lacerations have bruised and contused margins and surroundings when compared to cut injuries.