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Global Online Journal of Academic Research (GOJAR), Vol. 3, No. 2 April 2024 

 

 

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A STUDY ON THE CADAVERIC ANATOMICAL 

DIMENSIONS OF THE PTERION IN A NIGERIAN 

POPULATION:  

An Important Landmark Guide in Lateral Approach Surgeries* 

 

By 

Ozor I.I, Nkwerem S.P.U, Iroegbu-Emeruem L, Nnachi S.I, Asimadu 

I.N, Aroh V.E & Elisa F.I. 

 

Abstract  

Background: The pterion is a craniometric point near the sphenoid fontanelle of 

the skull. In neurosurgery, pterional approach is one of the most widely used 

operative interventions and treatments. The aim of this study is to determine the 

cadaveric anatomical features of the pterion in a Nigerian population and 

compare with those of different populations. 

Materials and method: This is an observational study carried out in the Human 

Anatomy Departments of Enugu State University College of Medicine, 

University of Nigeria College of Medicine, Nnamdi Azikiwe University College 

of Health Sciences, Ebonyi State University College of Medicine and 

Chukwuemeka Odumegwu Ojukwu University College of Medicine, Nigeria, 

using fifty cadaveric skulls of both sexes. Oral approval was gotten from the 

various departments on presentation of letter of introduction from the Department 

of Anatomy, Enugu State University of Science and Technology, Enugu. 

Results: The sphenoparietal type of pterion was found to be the most common 

type (78%) on the right and (74%) on the left, followed by frontotemporal which 

is (14%) on the right and (18%) on the left; the least common types of pterion is 

stellate and epipteric with (4%) on the right and the left.  

Conclusion: Despite the significant variation between the left and right sides of 

the pterion, the pterions found in cadaveric skulls of Nigerian origin are similar to 

those of other population. 

 

Introduction 

The pterion, which is an important landmark in human craniometry, is a 

point of convergence of the frontal, sphenoid, parietal, and squamous 

temporal bones of the calvarium (Vigo et al 2020). It is a very useful 

landmark in surgical planning and orientation intraoperatively. Murphy 

described four types of pterions namely sphenoparietal, frontotemporal, 

stellate, and epipteric (Murphy, 1956). See figure 1. Occasionally, a small 



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epipteric bone may be present. 

The pterion is a reference area in locating the Broca’s motor speech area, 

anterior pole of the insula, and middle cerebral artery (Sindel et al, 2016). 

It is also very useful in neurosurgical approaches, especially for anterior 

circulation aneurysm (Bhargavi, C., Saralaya, V., & Kishan, K., 2011). 

Furthermore, the pterion which is the weakest areaof the skull, overlies the 

middle meningeal vessels (Ilknur, Mustafa, & Sinan, 2009), which are the 

major cause of extradural hematoma in head injuries. (Lama, Mottolese, et 

al, 2000). Previous cadaveric study around the pterion in SouthEast 

Nigeria was a single centre study (Ukoha et al, 2013). Besides, the 

relationship of pterion with the mastoid process, another important 

neurosurgical landmark, was not explored in the study. This multicenter 

study is an attempt to determine the cadaveric anatomical features of the 

pterion in a Nigerian population, compare previous studies in Nigeria and 

with those of different populations. 

 

Figure 1: Skeletal picture of the types of pterions. (Murphy, 1956 & Oguz et al., 2004). 

 
 

Figure 2: Types of pterions. (Çimen et al, 2019) 



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                 Materials and Methods 

This is an observational study carried out in the human Anatomy 

Departments of Enugu State University College of Medicine, University of 

Nigeria College of Medicine, Nnamdi Azikiwe University College of 

Health Sciences, Ebonyi State University College of Medicine and 

Chukwuemeka Odumegwu Ojukwu University College of Medicine. Oral 

approval was gotten from the various departments on presentation of letter 

of introduction from the Department of Anatomy, Enugu State University 

of Science and Technology, Enugu. Cadaveric skulls irrespective of males 

and females with intact calvaria and well-defined sutures were included in 

the study, while damaged skulls and very old skulls with obliterated 

sutures were excluded. 

Study was conducted on fifty human unsexed adult skulls. Dry skulls are 

taken up for the study as there is paucity of cadavers. Pteria was classified 

based on Murphy’s classification. Measurements were taken on both sides 

of the skull from the center of the pterion to the midpoint of zygoma, tip of 

the mastoid process, Bregma and to the fronto-zygomatic suture using 

Vernier calipers. Each of the measurements were taken twice then 

averaged so as to minimize bias errors. Relevant findings regarding 

various types of pterions and position of pterion were noted. Values were 

recorded separately on right and left sides and compared. Values were also 

compared with previous studies for their statistical significance. 

The Measurement of Pterion 

This was done in the laboratory, the data collected in this study were 

statistically analyzed using descriptive statistics like the percentages, mean 

and standard deviation. To compare between right and left sides, One- 

Way ANOVA (Analysis of variance) was used. 

Results 

In the present study, we found sphenoparietal type of pterion to be the 

most common type (78%) on the right and (74%) on the left, followed by 

frontotemporal which is (14%) on the right and (18%) on the left, the least 

common types of pterion are stellate and epipteric with (4%) on the right 

and the left. 

Table 1: The percentage distribution of various types of pterions is 

shown in the table below. 

 



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Types of Pterions Right Percentage (%) Left Percentage (%)  

SPHENOPARIETAL 39 78 37 74 

FRONTOTEMPORAL 7 14 9 18 

STELLATE 2 4 2 4 

EPIPTERIC 2 4 2 4 

TOTAL 50 100 50 100 

 

The table below is a comparison of left and right sides using standard 

deviation 

Table 2a (right side) 

TYPE RIGHT X X-X (X-X)2 

SPHENOPARIETAL 39 26.5 702.25 

FRONTOTEMPORAL 7 -5.5 30.25 

EPIPTERIC 2 -10.5 110.25 

STELLATE 2 -10.5 110.25 

TOTAL 50  953 

 

Standard deviation S for the right =17.8 

Table 2b (left side) 

TYPE LEFT X X-X (X-X)2 

SPHENOPARIETAL 37 24.5 600.25 

FRONTOTEMPORAL 9 -3.5 12.5 

EPIPTERIC 2 -10.5 110.25 

STELLATE 2 -10.5 110.25 

TOTAL 50  833 
 

Standard deviation S for the left= 16. 

Table 3: ANOVA TABLE 

Sources of variation Sum of square Degree of freedom Mean square  Fraction 

Treatment(α) 1782 (p-1) 594 594 

Error(E) 4 (P-1)4 1 - 

TOTAL 1786 7 - - 
 

The critical region is F>F (0.5) (3, 4) =F>6.59 

Since the calculated f~ ratio (594) is greater than the critical value (6.59) 

we reject the H0 at α = 0.05 and concluded that the varietal difference is 

significant. (Note this result is also significant at α = 0.01). 

Table 4: Comparing the distance from the pterion to mid-point of 

zygomatic arch(P-ZA), frontozygomatic(P-FZS), mastoid process (P-

MP) with that of other populations. 



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AUTHORS YEAR POPULATION DISTANCE(CM) 

   P-FZ P-ZA P-MP 

   Right Left Right Left Right Left 

Pretty Rathnakar et al 2019 India 4.0 4.0 3.2 3.2 8.3 8.3 

Sowya S et al 2017 India 3.42 3.33 4.0 3.99   

Ma et al 2012 Australia 2.6 2.5 3.4 3.4   

Iiknur et al 2009 Anatolian 3.3 3.44 4.05 3.85   

K.Natsis et al 2019 Greek 3.47 3.52 4.13 4.09   

Bhargavi et al 2011 India 3.93 3.8 4.42 4.45   

Adejuwon et al 2013 Nigeria 3.1 3.083 3.91 3.87   

Ukoha et al 2013 Nigeria 2.74+/-

.07 

2.74+/-

0.06 

4.02+/-

0.05 

4.01+/-

0.03 

  

Present study 2021 Nigeria 3.32 3.40 4.53 4.39 8.92 8.78 

 

Discussion 

The predominant pterion found in the present study is the Sphenoparietal 

type (78%) on the right and (74%) on the left, and this is similar to all 

other studies summarized in Table 4.  In the Asians, the Sphenoparietal 

pterion frequency ranged between 72% and 93.55%. The Japanese has the 

highest frequency with (93.5%) followed by the Indians with (72-77%). 

The Greeks has the lowest frequency (58.4%) followed by the Kenyans 

(66%). The high frequency of Sphenoparietal pterion could be as a result 

of evolution (Lui YH, et al 1999), given that it is the commonest type in 

primates (Ashley- Montagu M. 1933).   

In the present study, the vertical distance from pterion to zygomatic arch is 

found to be slightly more on the right side compared to the left side, while 

the pterion to Frontozygomatic suture was slightly more on the left 

compared to the right. According to measurement pterion was lying 

approximately 4.53cm above the arcus zygomaticus on the right side, 

4.39cm on the left side and 3.32cm behind the frontozygomatic suture on 

the right and 3.40cm on the left. A study done in Greek by K.Natsis et al 

(2019) shows the distance from the pterion to the zygomatic arch to be 

4.13cm on the right  and 4.09cm on the left, while the distance from the 

pterion to the frontozygomatic is 3.47cm on the right and 3.52cm on the 

left. In another study done in India by Bhargavi et al (2011) recorded the 

distance from the pterion to the zygomatic arch to 4.52cm on the right and 

4.45cm on the left, while the distance from the pterion frontozygomatic 

suture is 3.93cm on the right and 3.8cm on the left. Another study done in 

Anatolia by Iiknur et al (2009) shows the distance from the pterion to the 

zygomatic arch to be 4.05cm on the right and 3.85cm on the left, while the 

distance from the pterion to the frontozygomatic suture is 3.3cm on the 

right and 3.44cm on the left.  

Comparing the result from the present study to that of the result gotten 



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from other studies done in different populations it shows that the distance 

from the pterion to zygomatic arch is found to be slightly more on the right 

side compared to the left side, while the pterion to frontozygomatic suture 

is slightly more on the left compared to the right.                                                                                                          

Conclusion  

The pterions found in cadaveric skulls of Nigerian origin have the 

following features when compared to those of other population; Distance 

from the center of the pterion to mid zygomatic arch and mastoid process 

was found to be more on the right than the left, from the pterion to the 

frontozygomatic arch was found to be more on the left than the right and 

Bregma is equal on both sides. 

 

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* This is a revised version of an article of the same title published by the 

authors in 2023.  

 

 

 

Author Information: Ozor II is affiliated to 

Neurosurgery Unit, Department of Surgery, College of 

Medicine, Enugu State University of Science and 

Technology and Department of Anatomy, College of 

Medicine, Enugu State University of Science and 

Technology, Enugu. Email: ikemozor@yahoo.com 
 

 

 

 

Nkwerem SPU is of Neurosurgery Unit, Department of 

Surgery, College of Health Sciences, Nnamdi Azikiwe 

University Teaching Hospital. 
 

 

 

 

Iroegbu-Emeruem L is of Department of Surgery, 

Faculty of Clinical Sciences, College of Medical 

Sciences, Rivers State University, Port-Harcourt. 
 

 

 

 

Nnachi SI is of Department of Anatomy, College of 

Medicine, Enugu State University of Science and 

Technology, Enugu. 
 

 

https://pubmed.ncbi.nlm.nih.gov/23771454
https://scholar.google.com/scholar_lookup?journal=Niger+J+Clin+Pract&title=Anatomic+study+of+the+pterion+in+Nigerian+dry+human+skulls&author=U+Ukoha&author=CK+Oranusi&author=JI+Okafor1&author=OO+Udemezue&author=AE+Anyabolu&volume=16&issue=3&publication_year=2013&pages=325-328&pmid=23771454&


Global Online Journal of Academic Research (GOJAR), Vol. 3, No. 2 April 2024 

 

 

86 
 

 

 

Asimadu IN is of Department of Ophthalmology, Enugu 

State University of Science and Technology, Enugu. 
 

 

 

 

Aroh VE is of Department of Surgery, Federal 

University Teaching Hospital, Abakaliki. 
 

 

 

 

Elisa FI is of Department of Anatomy, College of 

Medicine, Enugu State University of Science and 

Technology, Enugu. 
 

 

 

 

 
 

AMA 

 

Ozor II, Nkwerem SPU, Iroegbu-Emeruem L, Nnachi SI, 

Asimadu IN, Aroh VE, Elisa FI. A Study on the Cadaveric 

Anatomical Dimensions of the Pterion in a Nigerian 

Population: An Important Landmark Guide in Lateral 

Approach Surgeries. Global Online Journal of Academic 

Research, 2024;3(2):78-86. https://klamidas.com/gojar-v3n2-

2024-05/. 

 

APA 

 

Ozor I.I, Nkwerem S.P.U, Iroegbu-Emeruem L., Nnachi S.I, 

Asimadu I.N, Aroh V.E, Elisa F.I. (April 2024). A Study on 

the Cadaveric Anatomical Dimensions of the Pterion in a 

Nigerian Population: An Important Landmark Guide in 

Lateral Approach Surgeries. Global Online Journal of 

Academic Research, 3(2), 78-86. https://klamidas.com/gojar-

v3n2-2024-05/. 

 

 

 

 

 

 

 

 

 

 

 


