30 



JO 



28 



FIG. 172. BASE OP THE SKULL SEEN FROM ABOVE. 



The frontal and occipital bones are coloured red ; the ethmoid and temporal bones, blue ; the 

 parietal, orange ; and the sphenoid is left uncoloured. 



1. Frontal bone. 24. 



2. Slit for anterior ethmoidal nerve. 25. 



3. Anterior ethmoidal foramen. 



4. Posterior ethmoidal foramen. 26. 



5. Optic foramen. 27. 



6. Foramen for internal carotid artery formed by 



anterior and middle clinoid process. 28. 



7. Small wing of sphenoid. 



8. Anterior clinoid process, in this case united on its 



medial side to the middle clinoid processes. 29. 



9. Posterior clinoid process. 30. 



10. Foramen ovale. 



11. Groove for middle meningeal artery. 31. 



12. Foramen spinosum. 32. 



13. Hiatnsjianalis facialis. 33. 



14. Line of petro-squamosal suture. 34. 



15. Internal acoustic meatus. 35. 



16. Groove for superior petrosal sinus. 36. 



17. Groove for sigmoid part of transverse sinus. 37. 



18. Jugular foramen. 



19. Canalis hypoglossi. 38. 



20. Groove for transverse sinus. 39. 

 .21. Internal occipital protuberance. 40. 

 '22. Ridge for attachment of falx cerebri. 41. 



23. Fossa for the lodgment of the occipital lobes of 

 the brain. 



Ridge for the attachment of the falx cerebelli. 

 Fossa for the lodgment of the left cerebellar 



hemisphere. 



Foramen occipitale magnum. 

 Groove for the sigmoid sinus turning into the 



jugular foramen. 

 Groove for the inferior petrosal sinus running 



along the line of suture between the petrous 



part of the temporal and the basi-occipital. 

 Depression for the_aeiailunar ganglion. 

 Middle cranial fossa for lodgment of the temporal 



lobes of the brain. 

 Foramen laceruni. 

 Carotid groove. 

 Dorsum sellse of sphenoid. 

 Leads into foramen rotundum. 

 Fossa hypophyseos. 

 Tuberculum sellae of the sphenoid. 

 Anterior cranial fossa for lodgment of frontal lobes 



of the brain. 



Cribriform plate of ethmoid. 

 Crista galli of ethmoid. 

 Foramen caecum. 

 Crest for attachment of falx cerebri. 



12 a 



