THE ENDOSKELETON: SKULL AND VISCERAL SKELETON 123 



h) Foramen rotundum. Third of the row; in the alisphenoid bone; trans- 

 mits part of the fifth nerve. 



/) Foramen ovale. Last of the four; in the alisphenoid; transmits part of the 

 fifth nerve. 



j) Canal for the Eustachian tube. In the anterior wall of the bulla, its roof 

 formed by the alisphenoid; for the passage of the Eustachian tube from the 

 pharynx into the bulla. 



k) Pterygoid canal. Each bulla terminates anteriorly in a point (styliform 

 process) lying on the basisphenoid; this point is directed to a minute opening, 

 the pterygoid canal, lying in the suture between the basisphenoid and the ptery- 

 goid process; for the passage of a branch of the fifth nerve into the bulla. 



/) Jugular foramen. Large foramen on the medial side of the posterior end 

 of the bulla, for the passage of the ninth, tenth, and eleventh nerves. 



m) Hypoglossal foramen. In the medial side of the preceding foramen for 

 the passage of the twelfth nerve. 



11) Stylomastoid foramen. At the ventral tip of the mastoid process for the 

 passage of the seventh nerve. 

 Rabbit: 



a) Incisive foramina. As in the cat but larger. 



b) Infraborbital foramen. As in the cat but more slitlike and elongated, 

 forming an infraorbital canal, opening into the orbit above the expanded part 

 of the maxilla. 



c) Nasolacrimal canal. As in the cat, situated under the pointed anterior 

 end of the supraorbital arch. 



d) Posterior palatine foramen. On the ventral side, in the suture between 

 the palatine process of the maxilla and the palatines; forms the anterior open- 

 ing of the palatine canal. The posterior opening is at the posterior end of the 

 expanded mass of the maxilla located in the orbit. This canal is for the passage 

 of a branch of the fifth nerve. 



e) Sphenopalatine foramen. In common with the posterior end of the 

 palatine canal just described; for the passage of branches of the fifth nerve. 



/) Anterior and posterior supraorbital foramina. The projecting anterior and 

 posterior ends of the supraorbital arch are continued in life by ligaments, thus 

 forming foramina, through which branches of the fifth nerve pass. 



g) Optic foramen. Large opening in the center of the orbit, for the passage 

 of the optic nerve. 



h) Orbital fissure. Posterior and ventral to the preceding, and including 

 the foramen rotundum of other mammals. For the third, fourth, and sixth 

 nerves to the eyeball, and the greater part of the fifth. 



i) Anterior, middle, and posterior sphenoidal foramina. Three foramina in a 

 row in the lateral lamella of the pterygoid process at the place where this is 

 continuous with the alisphenoid. For the passage of part of the fifth nerve. 



