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Clivus

clivus ossis occipitalis

The clivus is a sloped bony surface forming the central part of the posterior cranial fossa floor, composed of the body of the sphenoid superiorly (basisphenoid) and the basilar part of the occipital bone inferiorly (basiocciput). The basilar artery and the brainstem lie immediately anterior to the clivus, with the pons above and the medulla below. The abducens nerves emerge from the pontomedullary junction and ascend steeply along the clivus surface.

Region: Head & Skull

Clinical Relevance

Clinical Notes

Chordoma is the primary tumour of the clivus, arising from notochordal remnants in the midline skull base. It presents with diplopia from CN VI involvement or nasopharyngeal mass and requires extensive skull base surgery with high local recurrence rates. Clival meningiomas arise from the posterior dural surface, compressing the brainstem. Basilar invagination (upward migration of the odontoid into the foramen magnum) displaces the clivus and is a cause of brainstem compression in craniovertebral junction anomalies.

Pathology

Common Injuries & Conditions

Clival Chordoma

A malignant tumour of notochordal remnants at the clivus presents with insidious onset of diplopia from CN VI palsy, headache, and nasopharyngeal fullness; extensive endonasal or skull base surgery with proton beam or carbon ion radiotherapy offers the best chance of local control.

Basilar Invagination

Upward migration of the odontoid process through the foramen magnum into the posterior cranial fossa, compressing the clivus level of brainstem and causing progressive myelopathy, headache, and lower cranial nerve palsies requiring surgical decompression and occipitocervical fusion.