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The hypoglossal canal is located between the occipital condyle and jugular tubercle and runs obliquely forwards (posteromedial to anterolateral) allowing the hypoglossal nerve to exit the posterior cranial fossa.
Its proximal portion is often divided by a fibrous (sometimes ossified) septum, which separates the two roots of the hypoglossal nerve (these have formed by the convergence of numerous rootlets). These roots merge within the canal and a single nerve emerges.
In addition to the hypoglossal nerve, the canal also allows a meningeal branch of the ascending pharyngeal artery to enter the skull, and a multiple veins, forming the hypoglossal venous plexus, to exit 5.
The hypoglossal canal is most easily identified on axial or coronal images through the occipital condyles, where it can be seen passing anterolaterally from the posterior fossa into the upper neck.
On coronal imaging, the jugular tubercle appears beak-like extending over the hypoglossal canal. Combined with occipital condyle the coronal appearance is reminiscent of an eagle seen in profile, making this a convenient landmark 3,4.
may be enlarged and contain a persistent hypoglossal artery
osseous spurs protruding into the canal 6
complete osseous bridging along part or all of the length of the canal 6
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