title: Posterior condylar canals and posterior condylar emissary veins-a microsurgical and CT anatomical study.
abstract: The posterior condylar canals (PCCs) and posterior condylar emissary veins (PCEVs) are potential anatomical landmarks for surgical approaches through the lateral foramen magnum. We conducted computed tomography (CT) and microsurgical investigation of how PCCs and PCEVs can aid in planning and performing these approaches. We analyzed the microanatomy of PCCs and PCEVs using cadaveric specimens, dry skulls, and CT images. The recognition frequency and geometry of PCCs and PCEVs and their relationships with surrounding structures were evaluated. PCCs were identified in 36 of 50 sides in dry bones and 82 of 100 sides by CT. PCCs had a 3.5-mm mean diameter and a 6.8-mm mean canal length. We classified their courses into four types according to intracranial openings: the sigmoid sinus (SS) type, the jugular bulb (JB) type, the occipital sinus type, and the anterior condylar emissary vein type. In most cases, PCEV originated near the boundary between the SS and JB. PCCs and PCEVs can be useful anatomical landmarks to differentiate the transcondylar fossa approach from the transcondylar approach, thus preventing unnecessary injury of the atlantooccipital joint. They can also be used as landmarks when the jugular foramen (JF) and hypoglossal canal (HGC) are being exposed. The area anterior to the brain stem and the medial part of HGC can be accessed by removal of the lateral foramen magnum medial to PCC. JF and the lateral part of HGC can be accessed by removal of the skull base lateral to PCC without damaging the lateral rim of the foramen magnum.
authors.affiliation: Department of Neurosurgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga-shi, Saga, 849-8501, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Matsushima
authors.forename: Masatou
authors.initials: M
authors.lastname: Kawashima
authors.forename: Toshio
authors.initials: T
authors.lastname: Matsushima
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hiraishi
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Noguchi
authors.forename: Akio
authors.initials: A
authors.lastname: Kuraoka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001842:Bone and Bones / Q000033:anatomy & histology; D002102:Cadaver; D002548:Cerebral Revascularization / Q000379:methods*; D002550:Cerebral Veins / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D005539:Foramen Magnum / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009777:Occipital Bone / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery; D012886:Skull / Q000033:anatomy & histology; D014057:Tomography, X-Ray Computed