C4 



BONES OF THE HEAD. 



cribriform plate of the ethmoid ^vhere it is pierced by numerous small 

 foramina and rises to a convexity over the orbits. The foramen cfecum 

 is situated in front of the crista galli of the ethmoid bone. 



The middle fossa, on a lower level than the anterior, presents a mesial 

 and two lateral parts. The mesial part is small, being formed by the 

 olivary process and sella turcica of the sphenoid bone, and limited be- 



Fin;. 54. 



Fig. 54. — Antero-Posterior Vertical Section op the Adult Skull a little to 



THE left of the MIDDLE LINE. (A. T. ) A 



1, nasal bone ; 2, perpendicular plate of the ethmoid bone, with olfactory foramina 

 and grooves at its upper part ; 3, vomer ; 4, nasal process of the riglit superior maxillary- 

 bone, forming part of the wall of the right nasal fossa ; below this, the anterior extremity 

 of the right inferior turbinated bone overhanging x , which is the right inferior meatus of 

 the nose ; 5, crista galli ; 6, inner surface of the frontal bone ; 7, of the parietal bone ; 

 8, squaiuous part of the temporal ; 9, on the occipital bone below the internal occipital 

 protuberance ; 10, external occipital protuberance ; 11, on the condylar process below 

 the anterior comlylar foramen ; 12, on the posterior surface of the petrous bone below 

 the meatus auditorius intenius ; between 9 and 12, the gi-oove of the right lateral sinus ; 

 13, placed above the sella turcica ; 14, part of the left frontal sinus ; 15, part of the left 

 sphenoidal sinus, the figure being jjlaced on the septum of the sinuses ; 16, hard palate 

 and alveolar arch — the figure is placed near the lower opening of the posterior palatine 

 canal, and the grooves which extend forwards from it ; 17, anterior nasal spine ; 18, 

 section of the left superior maxillary bone, and near the place to which the line points, 

 the section of the lower part of the anterior palatine canal ; 19, on the inner surface of 

 the ramus of the lower jaw, below the sigmoid notch, and above the inferior dental fora- 

 men ; 20, inner surface of the body of the jaw on the mylo-hyoid ridge ; 21, surface of 

 section of the lower jaw to the left of the symphysis ; behind the symphysis, and between 

 21 and 22, the mental spines ; 23, groove fur the mylo-hyoid neiTe. 



