Role
of mastoid process in determination of sex
Thejeswar. E.P, Dr. M.S. Thenmozhi
Department of Anatomy, Saveetha
Dental College and Hospitals, Chennai.
*Corresponding Author E-mail: thejeswar24@gmail.com
ABSTRACT:
The aim of this research is to evaluate mastoid
process using human skull for determination of sex. The main purpose of this research is the ability to examine and determine the sex for
unidentified using mastoid process.50 male and 50 female undamaged skulls were
examined. The parameters like mastoid process size and index were examined.
Usually mastoid process is larger in males
than in females. But
mastoid process index is more in female than in male. This the basic concept for identification. Discriminant
function analysis revealed that mastoid process correctly classified the sex in
90 percent of the subjects and mastoid length was found to be the best
determinant for sex. A discriminant function equation
specific for the present study skeletal population has also been derived from
the variables. Intensive
insulin therapy has proven effective to delay and sometimes prevent the
progression of complications such as nephropathy, neuropathy or retinopathy.
However, it is difficult to achieve and maintain long term in most subjects,
either for compliance issues or for the increased risk of severe hypoglycaemic episodes, With these
antecedents, the purpose of this study is to determine the existence of sexual
dimorphism in the dimensions and the area of the mastoid triangle, measured
directly in the skull, by means of statistical and discriminant
function analysis.
KEYWORDS: Mastoid process, determination of sex , porion
, heron’s formula, asterion.
INTRODUCTION:
Determination of sex is important for identification
of human. Mastoid process plays a major role in determination of sex. In legal matters
individual can be identified either living or dead. The anatomical
and medical features
plays a major aspects to establish
the identity. The establishment of
identity is required
from fresh intact corpses, decomposed corpses,
mutilated and dismembered corpses
or skeletalised material. [1] In living, identification is
possible with absolute
fixation of the individuality but
in case of
advanced decomposed, mutilated or skeletalised
body it is
difficult to establish the
identity of the
dead body either
partially or completely, in such cases mastoid process helps in
identification. Bass says that
the skull is
probably the second
best region of
skeleton to determine
the sex. The studies of
the dimorphism of
mastoid process shows that between the sexes by the
use of its
measurement , the mastoid process is larger in the male than In female.[2]
In living,
identification is possible
with absolute fixation
of the individuality but in case
of advanced decomposed, mutilated or skeletalised
body it is
difficult to establish the
identity of the
dead body either
partially or completely. In such circumstances the identification of
human skeletal remains
a critical issue. In present forensic
scenario, skeletal bones helps in
identification of an individual.. In such case pelvis is
considered the best
bone to determine
the sex of an
individual.[3] but in the absence
of pelvis, mastoid process widely
considered the best
for determination of sex. Mastoid process is ideally bigger in males due to larger muscles that inserted
into the mastoid process in males. This study helps to achieve an ideal idea for sexual dimorphism of
mastoid process. Mastoid is Generally less prone to damage due to its safe
anatomical position. Mastoid region is one of the slow and late growing regions
In cranium[4]. Hence this region is considered as an important to identify and
asses otseometric bases. The technique
is based on the triangular
area calculation obtained between
the points porion, mastoidale and asterion, measured
from dry skulls.[5]. The main
objective of this study is to evaluate the mastoid process for different sex of
an individual's and signify the use of statistical approach in estimation of
sex using human skulls.
MATERIALS AND METHODS:
50 dry skulls
of known sex,
50 male and 50
female, from the department
of anatomy of kilpauk medical
college, Chennai were analysed
for the present study
after taking approval
of Saveetha Dental College and Hospitals
and written permission
from the concerned department. Adult
skulls of mature individuals, more than 18 years, without any damage on the mastoid bone,
were chosen for the study.
The skulls that present
evidence of injury or Any fracture or deformity
were excluded from
this study. All
the skulls were confirmed
of the individual
of native of
south India. The measurements are according to three points
on the mastoid
portion on either
side, porion
[upper most lateral
point of external
acoustic meatus], Mastoidale [the
most inferior point
of mastoid process], Asterion [the
meeting point of three posterior skull sutures] were
selected for measurements.
These craniometrical points
were marked. A triangle
was drawn using these
three points on dry
skull on both sides.
The points Porion, asterion and mastoidale were
shortly marked as PO, AS
and MA respectively. Measurements of
the dimensions of the mastoid tiangle were
taken using vernier caliper. The
calculation was done using heron’s formula. i.e The
area (mm2) of
the demarcated triangle
for each side of the skull
(right (R) and
left (L) sides)
was determined by Heron’s
formula.[6] and the
total value (T) of
these measures of
both sides was
calculated as per method
described by De Paiva and Segre[7], Helmuth[8],
Demoulin[9].Similar to Kemkes
and Gobel, lineal measures were directly carried out
using a digital caliper (0.01 mm). The mastoid triangle area was calculated by
means of the Herón formula.
Fig:1.1 Mastoid triangle
Fig.1.2 PO-AS
Fig.1.3 MA-AS
Fig.1.4 PO-MA
Male and
female right and
left side measurements
|
GROUP |
NUMBER |
MEAN |
SD |
|
Male right |
50 |
654.13 |
67.43 |
|
Male left |
50 |
651.73 |
63.54 |
|
Female right |
50 |
582.35 |
87.43 |
|
Female left |
50 |
586.86 |
82.86 |
Fig.1.5 area of male mastoid triangle
Fig.1.6 Area of male mastoid triangle
Fig.1.7 Area of female mastoid triangle
Fig.1.8 Area of female mastoid triangle
DISCUSSION:
The
analysis of the mastoid process characteristics is important in the
determination of sex for forensic purposes. The differences of mastoid are
unique to each population and thought to be influenced by genetic,
environmental and socio-economic factor. This study analyzes the dimensions of
the denominated mastoid triangle, defined according to that described by DePaiva and Segre, but measured directly on the skulls. The
findings shows mastoid process is larger in male and smaller in female. But
there are few differences as marked in by DePaiva and
Segre in their original article.[5]
This is because When supplementing the method with the discriminant
function analysis, we find poor discriminant
potential of the lineal dimensions used. It is necessary to keep in mind that
in the original method of DePaiva and Segre, one obtains
the lineal dimensions based on a plane image by means of a xerographic copy of
a structure of certain convexity (skulls), which diminishes the distance
between the points.[7] Measures obtained with a caliper are also
linear measuring a bowstring. we conclude that the lineal dimensions and the
area of the mastoid triangle. Thus, the discriminant
function equation is unique to skulls of the present study population.
RESULTS:
In all the
analysed skulls, all of the lineal dimensions and the calculated areas
where higher in males than in females. This data when put to statistical
analysis, proved the significant difference with p < 0.01 in all the values
calculated in males when compared with that of females.
Similarly,
on comparing the
male left and
female left side Area of triangle
in male varies
between -600-700mm in male and 500-600
mm in female, in majority of cases in
my study. According to
the study by Paiva LA and
Segre 12, male tringle area was
significantly greater than female
triangle area. Values
calculated according to their
study mean values
was: in female:
570.9 mm2 and 575.1
mm2 in right
and left sides.
In male: 723.9 mm2
and 731.2 mm2 in
right and left sides. In
our study male
right: 654.13 mm2, male
left: 651.73 mm2,
female right: 582.35 mm2, female
left : 586.86 mm2
was found..
Since this study
was based on
anthropometric techniques, it
surpasses in importance
the older studies
such as those
of Broca [10] and Martin [11]. It also improves on the
criteria reported by Bass, which were based only on descriptive anatomical
aspects. Here in the
present study, by
using a measurement
of the surface
area, or in
other words, by using the
result product between
2 values, our results improve upon those studies by Schultz [12], Schaefer [13] which used only single
measurements.
As both the
graph shows, when
the measurement values are
plotted in ascending
order, the Heron’s triangle measurements
are found more
in males as compared
to females. This proves that
mastoid dimensions and
mastoid triangular area in
male are significantly
larger than those of
the female.
CONCLUSION:
This is an attempt to
validate the osteological criterion
for sex determination
based on the
mastoid process. The proper
identification of landmarks,
careful measurements and strict
statistical methods will yield reliable results.The present day study have provided a good idea for
sex determination in individuals using a
fragmentary piece of skull bone which is mastoid process. And the calculations
using Heron’s formula proves that the mastoid process is bigger in males than
in females.
REFRENCES:
1.
Pekka Saukko, Bernard
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Bass WM
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osteology:
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Editor, 1971.
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Byers
SN, Introduction to
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textbook, 3rd edition, 2002,pp176-186
4.
Humphrey
LT. Growth pattern in modern human
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Paiva LA,
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sexing the human
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Z Morphol
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Received on
20.05.2015 Modified
on 13.06.2015
Accepted on
17.06.2015 ©A&V Publications All right reserved
Res. J.
Pharmacology & P’dynamics. 7(2): April- June
2015; Page 76-81
DOI: 10.5958/2321-5836.2015.00016.6