The jugular foramen is a large aperture in the base of the skull. It is located behind the carotid canal and is formed in front by the petrous portion of the temporal, and behind by the occipital; it is generally larger on the right than on the left side. The jugular foramen may be subdivided into three compartments, each with their own contents: The anterior compartment transmits the inferior petrosal sinus. The intermediate transmits the glossopharyngeal (IX), vagus (X), and accessory nerves (XI). The posterior transmits the sigmoid sinus (becoming the internal jugular vein) and some meningeal branches from the occipital and ascending pharyngeal arteries.