The mastoid emissary foramen (MEF) is an anatomically variable opening located within the temporal bone that allows passage of the mastoid emissary vein (MEV), which connects the sigmoid sinus to extracranial venous channels. Its occurrence and dimensions show wide variation among individuals and populations, making it of particular surgical and anatomical importance. The foramen is generally found at or near the posterior margin of the mastoid process of the temporal bone or close to the occipitomastoid suture. This study aimed to describe in detail the anatomical and morphological features of the MEF in adult human skulls and to assess its prevalence, position, number, and size. In this study 48 adult human dry skulls (96 hemiskulls) of undetermined sex were macroscopically examined. Each temporal bone was evaluated for the presence, number, and diameter of the MEF using standardized measurement techniques. Among the examined specimens, the MEF was absent in 10 skulls (21 %), unilateral in another 10 skulls (21 %), and bilateral in 28 skulls (58 %). Out of 96 temporal bones assessed, 42 (43.75 %) exhibited a single MEF, 12 (12.5 %) showed double foramina, and 22 (22.9 %) presented with triple foramina. The foramen diameter demonstrated wide variation, with a mean of 3.16 ± 1.68 mm and a range between 0.18 and 5.6 mm. The MEF demonstrates marked variability in position, size, and number. Recognizing these variations is vital for radiologists, anatomists, and surgeons, as accurate anatomical knowledge helps avoid vascular injury and minimize complications during skull base or mastoid surgical procedures.
