Scalp, Cranial Fossa, and Cavernous Sinus: Learning Objectives

True/False

1. The coronal suture and the sagittal suture meet at bregma.
2. Arachnoid granulations reside within bony topographies called the granular foveolae.
3. Separating the anterior cranial fossa from the middle cranial fossa is the anterior ridge of the chiasmatic groove.
4. The tuberculum sellea extends anterior and superior to end a the posterior ridge of the chiasmatic groove.
5. The posterior openings of the optic canals face into the middle cranial fossa.
6. The superior petrosal ridge separated the middle cranial fossa from the posterior cranial fossa.
7. The frontal and parietal emissary veins drain the region of the frontal air sinus and the scalp into the superior sagittal sinus.
8. The inferior petrosal sinus drains from the cavernous sinus directly into the internal jugular vein.
9. The mastoid emissary vein connects intracranial venous drainage with the external vertebral venous plexus.
10. The most anterior extent of the superior sagittal sinus may connect to the nasal cavity by way of the foramen cecum.
11. At the posterior extent of the tentorial notch is the meeting of the straight sinus with the inferior sagittal sinus.
12. The superior petrosal sinus connects the cavernous sinus with the transverse sinus.
13. The superior and inferior ophthalmic veins connect orbit with the cavernous sinus.
14. An emissary vein through the cartilage of the lacerate foramen connects the cavernous sinus to the pterygoid venous plexus.
15. The inferior petrosal sinus connects the cavernous to the basilar venous plexed and then to the internal anterior vertebral venous plexus.
16. The sphenoparietal sinus connects the cavernous sinus to the region of the pterion.
17. The anterior and posterior intercavernous sinuses connect one cavernous sinus to the other cavernous sinus.
18. The occipital sinus connects the confluence of the sinuses with the internal posterior vertebral venous plexus.
19. The marginal sinus surrounds the margin of the foramen magnum.
20. The right transverse sinus tends have a larger diameter than the left transverse sinus.
21. The diaphragma sellae forms a dural shelf superior to the hypophyseal fossa and contains the intercavernous sinuses.
22. The greater superficial nerve, but not the lesser superficial petrosal nerve, extends into the lacerate foramen.
23. The facial, vestibulocochlear, glosspharyngeal, vagus, and hypoglossal nerves all leave the posterior cranial fossa to become extracranial.
24. The cribriform plate of the ethmoid bone is located in the anterior cranial fossa.
25. The clivus is part of the sphenoid bone.
26. The cavernous sinus has immediate drainages into the superior petrosal sinus, inferior petrosal sinus, basilar venous plexus, sphenoparietal sinus, ophthalmic vein, pterygoid venous plexus, and the intercavernous sinus.
27. The straight sinus drains directly into the confluence of sinuses.
28. The basilar venous plexus is continuous with the internal posterior vertebral venous plexus.
29. The lacus lacrimalis
30. The great vein of Galen combines with the inferior sagittal sinus to form the straight sinus.
31. The emissary veins connect extracranial venous drainages with intracranial venous drainages.
32. Ligation of the internal jugular veins at the base of the skull does not block intracranial venous drainage.
33. The inferior sagittal sinus is within the inferior margin of the tentorium cerebelli
34. The foramen cecum, when patent, provides a venous communication between the superior sagittal sinus and the nasal cavity.
35. The anterior free margin of the tentorium cerebelli forms the tentorial notch or incisura.
36. The superior petrosal sinus passes superior to the trigeminal nerve.
37. The repeating cascade of symptoms of cavernous sinus infection reflects, in part, spread of infection through the intercavernous sinus.
38. The intercavernous sinus surrounds the pituitary stalk.
39. The anterior lip of the chiasmatic groove defines, in part, the boundary between the middle and inferior cranial fossae.
40. The turberculum sellae extends from the hypophyseal fossa to the posterior lip of the chiasmatic groove.
41. The clivus extends from the foramen magnum to the inferior margin of the dorsum sellae.
42. The lateral walls of the hypophyseal fossa are formed by the medial walls of the cavernous sinus.
43. The occipital sinus is directly continuous with the anterior internal vertebral venous plexus.
44. The basilar venous plexus directly connects with the anterior internal vertebral venous plexus.
45. The superior orbital fissure marks the anterior boundary of the cavernous sinus.
46. Structures that pass through the superior orbital fissure become a content of the cavernous sinus.

Essay

1. Discuss possible routes of infection into the cavernous sinus from each of the following locations. As always, include key relations for each anatomical pathway. (30 pts)
   1. face near the lateral aspect of the upper lip
   2. lower border of mandible near the angle
   3. scalp (What fascial boundaries are compromised?)
   4. ischiorectal fossa (this is not a typographical error)
   5. frontal sinus (air sinus)
   6. sphenoid sinus (air sinus)
   7. maxillary sinus
   8. mastoid air cells
   9. ethmoid air cells
   10. buccopharyngeal fascia
   11. prostate (this is not a typographical error)
2. Discuss the boundaries (6 directions), contents, and relations of the cavernous sinus. In the event of infection, discuss the cascade of symptoms from early onset to death.
3. A patient has an infection on the lateral side of the nose. There is loss of lateral gaze (inability to abduct the eye) on the same side. Discuss the relevant spread of infection. What structures are vulnerable to injury?
4. An early procedure to limit spread of a facial infection into the cavernous sinus was to ligate (suture closed) facial vein communications into the orbit (e.g. supratrochlear, supraorbital, and other veins entering the orbit from the face). Unfortunately, this procedure is not entirely effective. Suggest an additional venous ligation and explain.
5. Discuss the relations (six directions) of the sphenoid sinus. Include mention of structures at risk during surgery involving the sphenoid sinus.