Petroclinoid ligament

The petroclinoid ligament (PCL; petrosphenoidal ligament or Gruber’s ligament) extends from the cephalic end of the clivus anteriorly to its posterior attachment on the petrous tubercle of the petrous apex.

The term “petroclinoid ligament” may be confusing because the but the ligament does not have attachment on the posterior clinoid process, so an alternative term is the” petrosphenoidal ligament” or “superior sphenopetrous ligament”, but these term are only listed as synonyms in the Terminologia Neuroanatomica.

The trajectory of the petroclinoid ligament follows a lateral to medial, posterior to anterior, and caudocephalic course parallel to the petroclival dura mater and immersed into the petroclival venous confluence, a venous confluence that drains the cavernous, inferior petrosal and basilar clivus sinuses into the jugular bulb in the ipsilateral jugular foramen. The  petroclinoid ligament  divides the petroclival venous confluence into two compartments, superior and inferior. 

It is important to note that the petroclinoid ligament (PCL) and the posterior petroclinoid fold (PPCF) are independent structures; their contents, anatomical relationships, and clinical manifestations – when injured – are very different:

• The posterior petroclinoid fold is a fold of the dural tent that contains the petroclival venous confluence

• The petroclinoid ligament is more closely related to the porus trigeminus and oculomotor trigone and is therefore associated with different clinical and surgical relationships.

The petroclinoid ligament provides a roof for the abducens nerve canal (Dorello’s canal) that is an osteofibrous canal marking the passage of the abducens nerve as it pierces the dura in the subarachnoid space.

The petroclinoid ligament is ossified in approximately 6.5%-12.1% of the general population. Ossification can be unilateral or bilateral. Note that the term “petroclinoid bone” refers to the ossification of the posterior petroclinoid dural fold forming a bar of bone spanning the roof of the porus trigeminus, and not to the complete ossified petroclinoid ligament.