The Study On The Microanatomy Of Operative Approaches To The Jugular Foramen Region

Objective1.To study microsurgical anatomy of the jugular foramen area,therefore provide anatomical bases for surgical approach to the jugular foramen lesions.2.Mimicking these surgical approaches,describe operative approaches of the scope and compare difference of these operative approaches. Methods1.The jugular foramen area exposure of 12 formalin-fixed adult brain specimens(24sides) were dissected under the surgical microscope. The microsurgical anatomy construction of the jugular foramen area and surroundings were recorded and photographed,measured and counted. 2. The approaches were made respectively on twelve specimens,Three directions approaches were evaluated. Results1. The jugular foramen area and surroundings were observed and recorded on head specimens. Significant asymmetry of the sigmoid sinus and jugular bulb in both sides of 12 cases was demonstrated.The diameter of the right sigmoid sinus and jugular bulb was bigger than the left.The unilateral high jugular bulb in 2cases were found.The unilateral intrajugular process between occipital and temporal bone in intrajugular compartment was integrated with sclerite in 3 cases.2.Protection of the facial nerve was important. The digastric ridge is an important landmark for defining the exit of the VIIth nerve. The facial nerve was carefully skeletonized. Constant irrigating prevented thermal injury. The periosteum around the facial nerve is very adherent,these is kept intact to protect the facial nerve. Stylomastoid artery is protected too,which is the blood supply of the facial nerve.3.It is important to identify and protect the vertebral artery in these approaches. The suboccipital triangle is made up of the three muscle. It is the important anatomic landmark for the exposure of the vertebral artery.The structure may not always be a good landmark. Variations of the artery is existed. Following the lamina of C1 conform the horizontal sulcus. It courses behind the lateral mass of C1.The posterior spinal artery and posterior inferior cerebellar artery exist variation. They may arise extradurally from the vertebral artery. The vertebral artery and branches should be protected carefully when the occipital condyle is grinded.4. Far lateral approach is representative posterior approach to the jugular foramen area.Transcondylar transprotuberance transtubercular approach additionally provides exposures.These include posterior and partial lateral aspects of the jugular foramen,CPA and petroclival region.5.A combination approach is representative lateral approach to the jugular foramen area.These include transmastoid, retro- and infralabyrinthine, transjugular, and so on. Multidirectional exposures for the jugular foramen area can be realized.6.The representative anterior approach to the jugular foramen area is the anterior infratemporal and infratemporal fossa approach. Exposures to the anterior inferior and partial lateral aspects of the jugular foramen lesions,high cervical approach and petroclival region can be realized. Conclusion1.The study of microsurgical anatomy aproaches of the jugular foramen area has important significance on operation and imageology.2.The three directions approaches provide respective exposure scopes of the jugular foramen area to resect lesions. These have respective range of application,and these exposure scopes are crossed.3.The three directions approaches are impeded by many important structures,including mastoid、the facial nerve、styloid process、the vertebral artery and so on.4. Instability of the craniovertebral junction、hypoglossal canal and scope of lesions are concerned when occipital condyle is grinded.5.The research about these operative approaches provides reference value about surgical treatment of the jugular foramen lesions.