Anthropometric Analysis of the Human Skull for Developmental Left-Sided Asymmetry, New Finding.

[BACKGROUND] Facial and cranial asymmetry is common in bilateral vertebrates, particularly human beings. Through years of injecting fillers and performing face-lift operation on patients, we began to observe that more fillers were required on the right side to reach symmetry and also more loose skin and soft tissue was observed on the right side in the majority of patients (Fig. 5). Here, we conducted an analytical study to comprehensively measure human skulls in order to observe and quantify this difference.

[METHODS] We collected forty-one natural skulls available from five medical schools of Tehran province in Iran. Standard photography was conducted from the front, lateral, and superior views. Measurements and statistics were completed using Image J software (National Institutes of Health) for exact comparison of fixed-point distances on the samples.

[RESULTS] Comparison of right and left dimensions on the skulls revealed several fixed asymmetries. The most significant differences were measurements around the orbit. The distance between the upper orbit point and zygion (zy), zygion to sub-nasal, and orbital areas were significantly larger on the left side. Measuring the anterior gonion-pogonion distance showed a wider mandibular body on the left side. We did not find any considerable differences between any other left-sided and right-sided skull dimensions.

[CONCLUSIONS] Asymmetry of the face and body is a general rule in human anatomy, but correlation and consistency of this asymmetry between the left and right sides is a novel finding based on our measurements. Our findings showed that the orbit was significantly bigger in width, height, and surface area on the left side. We also quantified a narrower mandible on the right side. We hope these findings can be translated to aesthetic surgery practice to make the plastic surgeon and patient more familiar with the patient's specific anatomy in order to better predict, plan, and successfully implement aesthetic procedures such as injecting fillers or doing peri-orbital procedures.

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