The course of the glossopharyngeal nerve is described in cisternal, foraminal and extracranial subsections.
Two landmarks help to identify the GPhN in the subarachnoid space:
the choroid plexus of the lateral recess of the fourth ventricle
the dural entrance porus of the jugular foramen.
The opening of the cochlear aqueduct, the mastoid canaliculus, and the inferior tympanic canaliculus are three landmarks of the GPhN within the jugular foramen.
Finally, the base of the styloid process, the base of the styloid pyramid, and the transverse process of the atlas serve as three landmarks of the GPhN at the extracranial region in the infratemporal fossa.
The PICA runs very close to the four lower cranial nerves, loops around the hypoglossal nerve, and then courses along the fibers of the accessory nerve