Left cavernous sinus. The posterior genu of the cavernous ICA has been gently retracted forward to show the posterior compartment of the cavernous sinus. This compartment contains the abducens nerve which is located at the most inferior level of the compartment just behind the short ascending cavernous ICA. The petro-sphenoidal or Gruber’s ligament, partially transected here, is located posterior to the abducens nerve at this level. The branches of the meningohypophyseal trunk are typically located at the transition between superior and posterior compartments. Oculomotor and trochlear nerves are seen at the superior compartment. (Image courtesy of JC Fernandez-Miranda)