Morphological types and localization patterns of pterion in the skulls of adults from southeastern China

To study the morphological types and relative location of the pterion and its precise relationship with the middle meningeal artery (MMA) in the skulls of adults from southeastern China.

Dry skulls (n = 250) of adults were obtained from a university specimen bank and analyzed. The morphological types of the pterions were observed. The distances from the center of the external pterion (Pec) to the relevant intracranial and extracranial marker points were measured using a digital vernier caliper. The anterior, middle, and posterior end points of the external pterion were drilled perpendicular to the bone surface. The precise relationships of the external pterion with the internal pterion and the groove of the frontal branch of the MMA were observed and measured after sawing the skull.

The morphological types of the pterion in the skulls of adults from southeastern China were sphenoparietal suture (SP) (85%), epipteric (12.4%), frontotemporal suture (1.4%), and stellate (1.2%) types. The mean widths of the external and internal pterions were R, 10.68 ± 4.22 mm; L, 11.13 ± 4.40 mm and R, 14.66 ± 4.04 mm; L, 14.14 ± 4.29 mm, respectively, and the width of the internal pterion was slightly longer than that of the external (P < 0.05). No significant difference in pterion width was found between the genders or sides of the skull (both P > 0.05). The distances from the Pec to the posterolateral aspect of the frontozygomatic suture, zygomatic process of the frontal bone, midpoint of the zygomatic arch, and external acoustic meatus were 29.95 ± 3.75 mm, 34.88 ± 4.08 mm, 40.86 ± 3.59 mm, and 53.79 ± 3.82 mm, respectively. These distances were slightly longer on the right side of the skull than on the left side (P < 0.01) and longer in men than in women (P < 0.01). The distances from the Pec to the frontal crest, optic canal, and anterior clinoid process were 62.79 ± 1.15 mm, 45.39 ± 2.48 mm, and 45.47 ± 2.05 mm, respectively. The external and internal pterions were not on the same level, and all the internal pterions were located below the external ones. In the vast majority of the skulls, the groove of the frontal branch of the MMA passed through the posterior end of the external pterion (Pep) or the area between the Pec and Pep.

The morphology of the pterion in the skulls of adults from southeastern China is predominantly of the SP type, mostly symmetrically distributed. The distance from the pterion to the extracranially relevant marker points differs among the ethnic groups, between the genders, and between the sides of the skull. All the internal pterions are located below the external ones. Most of the frontal branch of the MMA is located below the mid-posterior segment of the lateral pterion. The characterization of the morphology, the relative position of the pterion and the precise relationship of this structure with the MMA in the skulls of adults from southeastern China may provide an anatomical basis for teaching and clinical practices.