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Hypoglossal Canal

canalis hypoglossi

The hypoglossal canal is a bony channel through the occipital condyle transmitting the hypoglossal nerve (CN XII) and an emissary vein. It lies immediately above the occipital condyle and opens superiorly into the posterior cranial fossa and inferiorly near the atlanto-occipital joint. Each occipital condyle contains one hypoglossal canal.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The hypoglossal canal is a site of condylar metastasis, primary glomus tumours, and nerve sheath tumours of CN XII that produce isolated hypoglossal nerve palsy with tongue deviation toward the affected side and progressive atrophy. CT shows bony expansion or destruction of the canal. The canal is an important landmark in skull base surgery and in occipital condylectomy for foramen magnum tumour access. Emissary vein within the canal provides a route for infection and thrombosis between the posterior fossa and the suboccipital venous plexus.

Pathology

Common Injuries & Conditions

Hypoglossal Canal Metastasis

Haematogenous metastasis to the occipital condyle expands the hypoglossal canal and compresses CN XII, producing progressive ipsilateral tongue atrophy and deviation, detected by CT showing bony erosion of the condyle and confirming primary malignancy workup.