Floor of cranial cavity

Structures inferior to anterior and middle cranial fossae; orbit and sinuses opened

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Image #50-5

Floor of cranial cavity

Structures inferior to anterior and middle cranial fossae; orbit and sinuses opened

Views of the dissection of the contents of the orbit from this approach are found in 54-1 ff.

1. Frontal sinus
2. Infundibulum leading into nasofrontal duct
3. Upper pointer: Frontal nerve Lower pointer: Levator palpebrae superioris
4. Posterior ethmoidal nerve (usually a branch of the ophthalmic nerve in this case the fibers accompany the trochlear nerve)
5. Posterior ethmoidal artery in posterior ethmoidal foramen
6. Lacrimal nerve and superior ophthalmic vein
7. Periorbita (area of fusion with common annular tendon)
8. Maxillary nerve (V2)
9. Trochlear nerve (IV)
10. Oculomotor nerve (III)
11. Abducens nerve (VI)
12. Vidian nerve of pterygoid canal (below floor of sphenoid sinus)
13. Semilunar ganglion (trigeminal)
14. Mandibular nerve (V3)
15. Cavernous nerve plexus
16. Ethmoidal cell (anterior)
17. Anterior ethmoidal nerve
18. Cribriform plate ethmoid bone
19. Anterior ethmoidal artery (in anterior ethmoidal foramen)
20. Ethmoidal cell (posterior)
21. Posterior ethmoidal vein
22. Upper pointer: Aperture of sphenoid sinus Lower pointer: Sphenoid sinus
23. Optic nerve (ll)
24. Internal carotid artery
25. Upper pointer: Circular sinus Lower pointer: Hypophysis (left half removed)
26. Sella turcica
27. Dorsum sellae
28. Basilar venous plexus