LOWER SKULL BASE - ANATOMIC STUDY WITH SURGICAL IMPLICATIONS

With advances in the lateral approaches to the skull base and the incr easing success of the management of jugular foramen lesions, a thoroug h knowledge of the anatomy of this region is needed. The purpose of th e present work is to study the detailed microsurgical anatomy of the l ower skull base and the jugular foramen area as seen through the later al approaches. Forty preserved skull base specimens and 5 fresh cadave rs were dissected. The shape of the jugular bulb and its relationship to nearby structures were recorded. The different venous connections o f the bulb were noted. The hypoglossal canal was identified and its co ntents were observed. The lower cranial nerves were studied at the lev el of the upper neck, at their exit from the inferior skull base, and in the jugular foramen. The results of the present study showed the co mplex and variable anatomy of this area. The classic compartments of t he jugular foramen were not always present. Cranial nerves IX through XI followed different patterns while passing through the jugular foram en, being separated from the jugular bulb by bone, thick fibrous tissu e, or thin connective tissue.