The microsurgical anatomy of the jugular foramen and caudal cranial nerves

Objective:To study the normal anatomic features of the jugul ar foramen and the Ⅸ,Ⅹ,Ⅺ crani-al nerves, and clarify the concept of the jug ular foramen on the basis of microscopic studies. Methods:Ten adult cadavers re moved of the brain and twenty-five dry skull species were observed and measured by using microscopic skills.Particular attention to the compartmentalization of the jugular foramen and the relationships of the caudal cranial nerves to the jugular bulb were analyzed. Results: Fiber septum(16 species,80%)or bony sept um(4 species, 20%) separating partly the cranial nerve Ⅸ from the cranial nerve Ⅹ and Ⅺ was observed. Only one dry skull specimens had a septum producing ent irely internal compartment of the jugular foramen. All nerves lay anteromedially to the jugular bulb with separate connective tissue sheaths. A dense tissue was always presented between the Ⅸ cranial nerve and the internal carotid artery. Conclusions: This study suggest that the jugular foramen can be divided into neu ral part, petrosal part and sigmoid part. The nerves come together by means of d iscrete trunks in the jugular foramen with loosing contaction each other. This c onfiguration may help us to recognize and protect the cranial nerves during the operation.