Friday, April 22, 2011

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.

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