































Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023


Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

16 
 

 

 

A Study on the Cadaveric Anatomical Dimensions of the 

Pterion in a Nigerian Population: An Important Landmark 

Guide in Lateral Approach Surgeries 

 

By 

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

IN, Aroh VE, Elisa FI 

 

 

 

Abstract 

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

skull. It is a crucial intraoperative landmark in surgical approaches. In neurosurgery, 

pterional approaches are used in various 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. 

 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

17 
 

 

 

Introduction 

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

skull. It is a point of convergence of the sutures between the frontal, 

sphenoid, parietal, and squamous temporal bones (Ilknur, Mustafa, & 

Sinan, 2009). There are varied patterns of articulation of these bones and 

sometimes a small epipteric bone may be present. There are four types of 

sutural pattern: Murphy described four types of pterions namely 

sphenoparietal, frontotemporal, stellate, and epipteric (Murphy, 1956). 

The pterion is located superior to the zygomatic arch and posterior to the 

frontozygomatic suture. This area is known as the weakest part of the 

skull, yet it overlies the course of the anterior division of the middle 

meningeal artery (Ilknur, Mustafa, & Sinan, 2009), thus making it 

vulnerable to rupture, leading to extradural hematoma in the event of a 

blunt trauma to the side of the head (Lama, Mottolese, et al, 2000). In 

addition, it acts as an important landmark for locating the Broca’s motor 

speech area, anterior pole of the insula, and middle cerebral artery 

(Apinhasmit, Chaisuksunt, et al, 2011). Intradural pterional approach is 

used as surgical approach to optic nerve sheath meningioma, whereas 

extradural pterional approach is used for optic nerve decompressions as 

well as for tumor resections and biopsies (Quinones-Hinojosa & 

Schmidek, 2012). This study is an attempt to determine the cadaveric 

anatomical features of the pterion in a Nigerian population and compare 

with those of different populations. 

 

Figure 1: Skeletal pictures of the types of pterions 

 

 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

18 
 

 

 

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. 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

19 
 

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. 

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) 

 

 

 

 

Standard deviation S for the right =17.8 

Table 2b (left 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 

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 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

20 
 

 

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. 

 

 

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 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

21 
 

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 

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. 

 

References 

Adejuwon, S., Olopade, F., & Bolaji, M. (2013). Study of location and 

morphology of pterion in adult Nigerian skulls. ISRN Anatomy, 1-

4. 

Bhargavi, C., Saralaya, V., & Kishan, K. (2011). Pterion: A site for 

neurosurgical approach. Int J Biomed Res, 2(12):588-594. 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

22 
 

Bhargavi, C., Saralaya, V., & Kishan, K. (2011). Pterion: A site for 

neurosurgical approach. Int J Biomed Res, 2(12):588-594. 

Eboh, D., &Obaroefe, M. (2014). Morphometric study of pterion in dry 

human skull bones of Nigerians. Int J Morphol, 32(1):208-13. 

Escosa-Bage´, M., Sola, R. G., Liberal-Gonza´lez, R., &Caniego, J. L.-C. 

(2002). Fusiform aneurysm of the middle cerebral artery. Revista 

de Neurologia, 655–658. 

Hussain, S., Mavishetter, G., Thomas, S., Prasanna, L., Muralidhar, & 

Magi, P. (2011). A study of sutural morphology of the pterion and 

asterion among human Indian skulls. Biomed Res, 22:73 5. 

Hussain-Saheb, S., Haseena, S., & Prasanna, L. (2010). pterion – Three 

case reports. Journal of Biomedical science and Research, 2(2): 

108–110. 

Ilknur, A., Mustafa, K. I., & Sinan, B. (2009). A comparative study of 

variation of the pterion of human skulls from 13th and 20th century 

anatolia. International Journal of Morphology, 1291–1298. 

Kaan, C., Ilhan, O., & Mehmet, C. (2019). Pterion types in Anatolian 

adult skulls. Rev Arg de Anat Clin, 11 (1): 8-17. 

Lang, J. (1984). The pterion region and its clinically important distance 

to the optic nerve. 2. Pterion region, distance to the optic nerve, 

Dimensions and shape of the recess or the temporal pole. 

Neurochirurgia (Stuttg), 27(2):31-5. 

Ma, S., Baillie, L., & Stringer, M. (2012). Reappreaising the Surface 

Anatomy of the Pterion and Its Relationship to the Middle 

Meningeal Artery. Clin Anat., 25:330-339. 

Matsumura, G., Kida, K., & Ichikawa, R. (1991). Pterion and epipteric 

bones in Japanese adults and fetuses, with special reference to their 

formation and variations. KaibogakuZasshi, 66(5):462-71. 

Mennan, E., Cem, K., Mehmet, T., Ufuk, C., & Ahmet, H. (2010). 

Localization of pterion in neonatal cadavers: a morphological 

study;Surg.RadiolAnat, 32: 545-550. 

Murphy, T. (1956). The pterion in the Australian aboriginal. Am J Phys 

Anthropol, 14:225 44. 

Mwachaka, P., Hassanali, J., & Odula, P. (2008). Anatomic position of 

the pterion among Kenyans for lateral skull approaches. 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

23 
 

Int.J.Morphol , 26(4): 931-933. 

Oguz, O., Sani, S., Bozkir, M., & Soames, R. (2004). The pterion in 

Turkish male skulls. Surg RadiolAnat, 26:220 4. 

Satheesha, N., & Sowmya, K. (2008). Unusual sutural bones at pterion. 

International Journal of Anatomical variations, 1: 19-20. 

Sowmya, S., Meenakshi, B., & Ranganath, P. (2017). Study of pterion: 

Its clinical and morphological aspects. Indian Journal of Clinical 

Anatomy and Physiology., 4(2):247-9. 

Sucharitha, & Roshni, B. (2016). Study of anatomic position of Pterion in 

dry human skulls in Karnataka. Scholars Journal of Applied 

Medical Sciences, 4(9B):3272-3276. 

W. Apinhasmit, S., Chaisuksunt, V., Thi-raphatthanavong, P., & 

Phasukdee, N. (2011). Anatomical considera- tion of pterion and its 

related references in thai dry skulls for pterional surgical approach. 

Journal of the Medical Association of Thailand, 205–214. 

Wandee, A., Supin, C., Vipavadee, C., Paphaphat, T., & Noppadol, P. 

(2011). Anatomical consideration of pterion and its related 

references in Thai dry skulls for pterional surgical approach. J Med 

Assoc Thai, (2); 205-214. 

Williams, P., Bannister, L., Berry, M., Collins, P., Dyson, M., & Dussek, 

J. (2006). Gray’s Anatomy. 40th edition. In C. livingstone. 

Yasargil, M., & Fox, J. (1975). The microsurgical approach to 

intracranial aneurysms. Surg Neurol, 7 – 14. 

Yuvaraj, M., & Sankaran, P. (2017). A morphometric study on different 

shapes of pterion and its clinical significance. Int J Pharm Bio Sc, 

8(2):999-1003. 

Zalawadia, A., Vadgama, J., Ruparelia, S., Patel, S., Rathod, S., & Patel, 

S. (2010). Morphometric study of pterion in Dry Skull Gujarat 

Region. Njirm, 1:25 9. 

 

 

 

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  



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

24 
 

 

 

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. 

 

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. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


