Ventral view of the right pontomedullary junction and cerebellum (cerebellopontine angle). The facial (CN VII) and vestibulocochlear (CN VIII) nerves exit at the lateral pontomedullary junction to enter the internal acoustic meatus. Where they emerge is just superior to the foramen of Luschka. Glossopharyngeal (CN IX) and vagus (CN X) nerves exit the medulla lateral to the olives. The spinal accessory nerve (CN XI) arises from the ventral horn cells of the upper five cervical spinal segments and ascends through the foramen magnum to exit through the jugular foramen with glossopharyngeal and vagus nerves. The probe is compressing the glossopharyngeal and vagus nerves to demonstrate the foramen of Luschka which is one of two lateral apertures that allow cerebrospinal fluid to drain from the fourth ventricle into the subarachnoid space. The foramen of Luschka is the opening of the lateral recess of the fourth ventricle into the cerebellopontine cistern.  (Image courtesy of AL Rhoton, Jr.)