THE JUGULAR FORAMEN - MICROSURGICAL ANATOMY AND OPERATIVE APPROACHES

THE JUGULAR FORAMEN, based on these studies of microsurgical anatomy, is divided into three compartments: two venous and a neural or intraju gular compartment. The venous compartments consist of a larger postero lateral venous channel, the sigmoid part, which receives the flow of t he sigmoid sinus, and a smaller anteromedial venous channel, the petro sal part, which receives the drainage of the inferior petrosal sinus. The petrosal part forms a characteristic venous confluens by also rece iving tributaries from the hypoglossal canal, petroclival fissure, and vertebral venous plexus. The petrosal part empties into the sigmoid p art through an opening in the medial wall of the jugular bulb between the glossopharyngeal nerve anteriorly and the vagus and accessory nerv es posteriorly. The intrajugular or neural part, through which the glo ssopharyngeal, vagus, and accessory nerves course, is located between the sigmoid and petrosal parts at the site of the intrajugular process es of the temporal and occipital bones, which are joined by a fibrous or osseous bridge. The glossopharyngeal, vagus, and accessory nerves p enetrate the dura on the medial margin of the intrajugular process of the temporal bone to reach the medial wall of the internal jugular vei n. The operative approaches, which access the foramen and adjacent are as and are demonstrated in a stepwise manner, are the postauricular tr anstemporal, retrosigmoid, extreme lateral transcondylar, and preauric ular subtemporal-infratemporal approaches.