Comprehensive microsurgical anatomy of the jugular foramen

Objective To study the dural architecture of the jugular foramen and the course and configuration of the cranial nerves in the jugular foramen. Methods The microsurgical anatomy of the jugular foramen was observed in 10 fixed cadavers with each consisting of the whole head and neck and injected with latex. The jugular foramen was exposed step by step via the infratemporal fossa type A of Fisch in 5 cadavers and the combined cervicomastoid and suboccipital far-lateral approach in 5 cadavers. Results A dural septum separated the glossopharyngeal nerve from the fascicles of vagus nerve and accessory nerve at the intracranial opening. The cranial nerves remained fasciculated within the foramen. All of these nerve fascicles lay medial to the superior jugular bulb with the glossopharyngeal nerve located anteriorly and the accessory nerve posteriorly. The rootlets from the cranial root of accessory nerve were considered to join the spinal root, traveling with it briefly, then separated within the jugular foramen to become a part of the vagus nerve. The jugular bulb and adjacent part of jugular vein received drainage from the sigmoid and inferior petrosal sinuses, the vertebral venous plexus, the venous plexus of the hypoglossal canal, the condylar emissary vein, and the vein coursing along the inferior aspect of the petroclival fissure. Conclusion The jugular foramen can be divided into petrosal part, intrajuguar part, and sigmoid part. The cranial nerves within the jugular foramen maintain multifascicular and the nerve fascicles are separated between each other. The accessory nerve has no cranial root; it only consists of the structure hitherto as its spinal root.