Morphological and Morphometric Analysis of the Occipital Condyles and Their Clinical Significance

TL;DR

This study analyzes the shape and size of occipital condyles in human skulls to improve surgical safety and understanding of craniovertebral anatomy.

Contribution

The study identifies a new morphological type of occipital condyle and provides detailed morphometric data relevant to surgical planning.

Findings

The foramen magnum had a mean sagittal diameter of 35.1 mm and transverse diameter of 29.5 mm.

Nine morphological types of occipital condyles were identified, including a new 'sausage type' configuration.

Bilateral condylar canals were present in 16 out of 32 skulls examined.

Abstract

Background

The occipital bone, located in the human neurocranium, forms the craniovertebral junction and plays a critical role in both structural support and neural protection. The occipital condyle is particularly significant in traumatic events, especially in high-impact injuries such as motorcycle accidents. In this study, we evaluated the anatomy of the occipital condyles, pharyngeal tubercle, and foramen magnum within this trauma-prone region. The goal was to contribute to medical education, improve surgical safety, and provide reference data for clinical applications.

Methodology

A total of 32 dry skulls from a modern Anatolian population were examined in the anatomy laboratory. Linear measurements were taken using a high-precision digital caliper. Parameters measured included the length and maximum and minimum widths of the occipital condyles, the sagittal and transverse diameters of the foramen magnum, and the distances from the pharyngeal tubercle to anatomical landmarks such as the basion, opisthion, and jugular foramen. Morphological classification of the occipital condyles was performed, and the presence of the condylar canal was also recorded. The Kolmogorov-Smirnov test was used to assess normality. Data were expressed as mean ± standard deviation and percentages. The chi-square test was used for categorical variables. For comparisons between two groups, the Student’s t-test (for independent samples) was used under parametric conditions, and the Mann-Whitney U test was applied otherwise. Statistical analysis was performed using SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA), with p-values <0.05 considered statistically significant.

Results

The mean sagittal diameter of the foramen magnum was 35.1 ± 2.4 mm, and the transverse diameter was 29.5 ± 2.0 mm. The occipital condyles were classified into nine morphological types. A previously undescribed configuration, provisionally termed the “sausage type,” was observed. Type 3 was the most common on the right side, whereas Type 5 predominated on the left. Bilateral condylar canals were present in 16 skulls and absent in five skulls.

Conclusions

This study identified morphometric variations of potential anthropological and clinical significance. The absence of the condylar canal may reduce risks such as bleeding, atlanto-occipital joint damage, and hypoglossal nerve injury during surgical procedures involving the condylar fossa. Conversely, the absence of the condylar canal may complicate surgery by eliminating an auxiliary venous drainage route to the internal jugular vein. Morphometric variations may influence the choice of surgical approach; for instance, a longer posterior intercondylar distance may provide greater working space during posterolateral approaches. Similarly, in endoscopic endonasal approaches to lesions ventral to the foramen magnum, large occipital condyles may narrow the surgical corridor. Therefore, detailed morphometric knowledge of the occipital condyles is essential for optimizing the safety and effectiveness of craniovertebral surgical interventions.

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