184 



OSTEOLOGY. 



The roof as seen in the section is formed by the nasal and frontal bones, the cribri- 

 form plate of the ethmoid, the body of the sphenoid and the sphenoidal conchse, 

 the sphenoidal process of the palate and the ala of the vomer. The floor, which is 



42 41 40 39 



FIG. 173. MEDIAL ASPECT OF THE LEFT HALF OF THE SKULL SAQITTALLT DIVIDED. 



The frontal, maxillary, and sphenoid bones are coloured red ; the parietal, nasal and palate bones, blue ; the 

 basilar part of occipital, yellow, and squama occipitalis, purple. The ethmoid and inferior concha, 

 together with the left ala of the vomer, are left uncoloured. 



1. Suture between parietal and temporal bones. 24. 



2. Remains of the subarcuate fossa. 25. 



3. Grooves for branches of the middle meningeal 26. 



artery. 27. 



4. Dorsum sellse. 28. 



5. Sella turcica. 29. 



6. Anterior clinoid process. 



7. Optic foramen. 30. 



8. Sphenoidal sinus. 31. 



9. Nasal surface of superior concha. 32. 



10. Cribriform plate of ethmoid. 33. 



11. Nasal surface of middle concha. 



12. Frontal sinus. 34. 



13. Nasal bone near spine of frontal. 35. 



14. Nasal bone. 36. 



15. Frontal process of maxilla. 



16. Middle meatus of nose. 37. 



17. Directed towards opening of maxillary sinus. 



18. Nasal surface of inferior concha. 38. 



19. Inferior meatus of nose. 39. 



20. Anterior nasal spine. 40. 



21. Foramen incisivum. 



22. Palatine process of maxilla. 41. 



23. Horizontal part of palate bone. 42. 



Posterior nasal spine. 



Hamulus of medial pterygoid lamina. 



Lateral pterygoid lamina. 



Superior meatus of nose. 



Spheno-palatine foramen. 



Pterygo - spinous ligament almost completely 



ossified to enclose a foramen. 

 Styloid process of temporal bone. 

 Angular spine of sphenoid. 

 Mastoid process. 

 Basion (mid-point of anterior border of foramen 



magnum). 



Internal acoustic meatus. 

 Canalis hypoglossi. 

 Groove for inferior petrosal sinus leading into 



jugular foramen. 

 Opisthion (mid-point of posterior border of 



foramen magnum). 

 Groove for sigmoid sinus. 

 Opening of mastoid foramen. 

 For transverse sinus and attachment of tentorium 



cerebelli. 



Fossa for lodgment of cerebellar hemisphere. 

 Internal occipital protuberance. 



nearly horizontal from before backwards, is formed by the palatine processes of the 

 maxillae and palate bones. On sagittal section the nasal cavity appears some- 

 what triangular in shape with the angles cut off; the base corresponds to the 

 floor ; the apertura piriformis and choana to the truncated anterior and posterior 



