ANATOMIC POSITION OF THE ASTERION

OBJECTIVE: The asterion is defined as the junction of the lambdoid, pa rie toomastoid, and occipitomastoid sutures, The asterion has been use d as a landmark in lateral approaches to the posterior fossa. However, its reliability as a landmark comes into question considering the app arent variability of its position. This study was performed to determi ne the reliability of the asterion as a surgical landmark. METHODS: On e hundred dried skulls were obtained for study, A 2-mm drill hole was placed at file asterion an each side. The position of the! drill hole on the inner surface of the skull was next determined and recorded. RE SULTS: The asterion was located over tile posterior fossa dura in 32% on the right and 25% on the left. its position was over the transverse or sigmoid sinus complex in 61% on the right and 66% on the left. The landmark was located above tile transverse-sigmoid sinus complex in 7 % on the right and 9% on the left. CONCLUSIONS: The asterion is not a strictly reliable landmark in terms of locating the underlying posteri or fossa dura, its location is very often directly over the transverse -sigmoid sinus complex, Burr holes placed at the asterion may often op en the bone directly over the sinus, leading to potential damage.