Anatomical Variation of Selected Cranial Emissary Foramina in Adult Greek Skulls: A Mixed Anatomical and Computed Tomography Study

Introduction Cranial emissary foramina (CEF) are variable osseous channels that may transmit emissary veins (EVs) between extracranial venous networks and intracranial dural venous sinuses. Their anatomical relevance depends not only on their presence but also on laterality, size, morphology, and relationships with adjacent cranial landmarks. This study aimed to evaluate the prevalence, laterality, morphology, morphometry, and topographic anatomy of selected CEF in an adult Greek sample using a mixed anatomical and computed tomography (CT)-based design. Methods This retrospective observational study included 200 adult specimens, comprising 50 dry skulls (25.0%) and 150 CT examinations (75.0%). The parietal emissary foramina (PEF), sphenoidal emissary foramina (SEF), mastoid emissary foramina (MEF), and posterior condylar canal (PCC) were assessed for presence, laterality, morphology, morphometry, and topographic relationships. Side-to-side variation, co-occurrence patterns, and exploratory associations with selected constant cranial foramina, craniometric parameters, sex, and specimen type were also examined. Interobserver reliability was assessed for continuous measurements. Results The PCC was the most frequent structure, identified in 162 specimens (81.0%), followed by the MEF in 157 (78.5%), the PEF in 137 (68.5%), and the SEF in 49 (24.5%). Among specimens in which the corresponding foramen was present, bilateral expression was observed in 64 PEF cases (46.7%), 12 SEF cases (24.5%), 74 MEF cases (47.1%), and 73 PCC cases (45.1%). The SEF showed the highest proportion of unilateral cases, with unilateral expression in 37 cases (75.5%). Morphologic classification showed a predominance of oval forms across the examined foramina. Morphometric profiles differed by anatomical region, with the SEF exhibiting the smallest dimensions and the PCC the largest. Topographic measurements demonstrated distinct regional relationships for each foramen. Co-occurrence analysis identified a selective association between the presence of SEF and PCC. Exploratory regression analyses demonstrated selective associations with skull base length, adjacent foraminal dimensions, cranial breadth, and sex. Interobserver reliability was high to excellent. Conclusions CEF were frequent but anatomically heterogeneous structures in this adult Greek sample. Their assessment should be region-specific and should integrate prevalence, laterality, morphometry, morphology, and topographic anatomy. The observed exploratory associations require confirmation in independent anatomical and imaging studies incorporating vascular imaging techniques to distinguish osseous foramina from functionally relevant EV pathways.