Jugular foramen

Hypoplasia or even aplasia of a sinus or part of it must be differentiated from thrombus by careful analysis of the standard anatomic sequences (Fig. 18.11). When present, the CCT scan should also be taken into account, since a hypoplastic transverse and sigmoid sinus typically demonstrates a smaller jugular foramen when compared to the normal side. 

The IJV begins at the jugular foramen and travels within the carotid sheath along with the carotid artery and vagus nerve. The relation of the IJV to the carotid artery is variable. In the superior aspect of the neck, the vein is posterior to the artery. The IJV spirals anterior and lateral to the common carotid artery in the lower neck. In 70% of cases, the vein lies anterolateral to the artery. In 14% of cases, the vein is directly lateral and in another 14% it is immediately anterior. Rarely (1%),... 

Furthermore, the analysis should include foramina and canals at the posterior and dorsal central skull base (jugular foramen, carotid canal, foramen lacerum, foramen ovale and spinosum, canalis n. hypoglossi) and as pseudofractures small sutures and canaliculi. 

Venous sinuses drain 95% of blood from the cranium via the Internal jugular vein. It is of crucial Importance that there Is proper relation and motion between the occipital and temporal bones, which comprise the jugular foramen, to have unimpeded venous drainage. The remaining 5% of venous blood drains via facial veins and the external jugular vein. 

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