Orientation of Nerves and Vessels of the Cranial Base Anatomy
1. Optic nerve (CN II)
2. Ciliary ganglion
3. Maxillary nerve (CN V2)
4. Artery and nerve of pterygoid canal
5. Greater petrosal nerve
6. Internal carotid artery (Petrosal part) and venous plexus
7. Facial nerve (CN VII)
8. Internal carotid nerve and nerve plexus
9. Accessory nerve (CN XI)
10. Internal jugular vein
11. Internal carotid artery
12. Superior cervical ganglion
13. Descending palatine artery
Comment: The pathway of the internal carotid artery (ICA) is tortuous. It enters the skull via the carotid canal in the petrous portion of the temporal bone and then is directed anteromedially and superiorly across the foramen lacerum (closed by cartilage). The ICA then ascends into the cavernous sinus and, just inferior to the anterior clinoid process, makes a 180-degree turn to pass posteriorly to join in the cerebral arterial circle (of Willis). A venous plexus accompanies the ICA from the carotid canal to the cavernous sinus, as does a plexus of postganglionic sympathetic nerve fibers (called the deep petrosal nerve) from the superior cervical ganglion. The deep petrosal nerve joins the greater petrosal nerve (preganglionic parasympathetic fibers from CN VII) to form the nerve of the pterygoid canal (vidian nerve).
Clinical: The close association of cranial nerves exiting the jugular foramen (CN IX, X, XI) and those associated with the cavernous sinus (CN III, IV, V1, V2, VI) may be involved in any trauma or pathology (e.g., tumor, abscess) that surrounds this confined bony region.