Petrosphenoidal ligament

Last revised by Dr Francis Deng on 20 Sep 2022

The petrosphenoidal ligament, also known as Gruber ligament or petroclival ligament, forms the superior border of Dorello canal, the conduit for the abducens nerve.

The ligament has previously been known as the petroclinoid ligament (ligamentum petroclinoideum) but it actually does not have attachment on the posterior clinoid process 4. The alternative name per Terminologia Neuroanatomica, is the superior sphenopetrous ligament (ligamentum sphenpetrosum superius).

The petrosphenoidal ligament runs from the petrous apex to just below the posterior clinoid process on the lateral border of the upper clivus 1,2,3. It courses immediately superior to and perpendicular to the abducens nerve (CN VI) 3.

On contrast-enhanced high-resolution steady-state free gradient echo sequences (such as CISS), the ligament is readily identified in about 60% of cases as a low intensity structure outlined by venous enhancement 3. The mean length is about 7 mm and it is occasionally ossified 3.

Named after Wenzel Gruber (1814-1890), a Russian anatomist, who described the ligament in 1859 2.

The main significance of the ligament is as a surgical landmark to preserve the abducens nerve 3. However, ossification of the petrosphenoidal ligament has been reported as a potential cause for entrapment of the abducens nerve within Dorello canal 1, but this explanation is questionable 3.

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