Variant Anatomy of the Jugular Foramen: An Osteological Study

Abstract

Background: Jugular foramen lesions are among the major complications of skull base surgery. Morphological variations in the structure are pertinent during interpretation of skull base radiographs and in surgical procedures within the foramen. This study therefore aimed at describing the morphology of the jugular foramen in a Kenyan population. Methods: One hundred and five adult skulls from the Nairobi National Museums were used. Jugular foramen septation, dome and dimensions were studied extracranially. Statistical analysis was performed using SPSS (Version 21.1 IBM). Results: Septation was present in 202 (96.2%) jugular foramina, type I partial septation being the most common (78.7%). A dome was observed in 81 (38.6%) jugular foramina. Respectively, the mean right and left anteroposterior dimensions were 11.17 ±2.05mm vs.8.88 ±2.30mm (p <0.001), mediolateral dimensions 17.47 ±2.18mm vs. 15.30 ±2.53mm (p <0.001), jugular dome depth 12.38 ± 2.64 mm vs. 11.25 ± 2.15 mm (p=0.054), posterior wall thickness7.95 ± 2.20mm vs. 9.68 ± 1.98mm (p <0.001) and medial wall thickness 3.73 ± 1.10 mm vs. 3.73 ± 0.98mm (p = 0.992). Conclusion: Partial septation, asymmetry in dimensions and a wide range in the dome depth of the jugular foramen were frequent. Preoperative imaging of jugular foramen morphology is therefore recommended to avoid inadvertent injury to its contents and surrounding structures owing to variability.

The Relation of the Extracranial Spinal Accessory Nerve to the Sternocleidomastoid Muscle and the Internal Jugular Vein

“…Studies have shown that indeed Kenyans have a larger IJV than other populations. 15 This might therefore explain the predominant medial relation of the SAN in our setting.…”