148 A MANUAL OF ANATOMY. 



The Nasal Fossae. Figs. 12, 13. 



DISSECTION. 



Take the lower segment of the skull and divide it with a saw anteroposte- 

 riorly just at one side of the vomer. 



Study the nasal fossae. Each nasal fossa is divided by the superior, mid- 

 dle, and inferior turbinated bones into the superior, middle, and inferior 

 meatus. 



The nasal duct opens into the anterior part of an inferior meatus, the infundi- 

 bulum opening of the frontal sinus and anterior ethmoidal cells is in the anterior 

 part of a middle meatus, and at the middle portion is the opening of the max- 

 illary sinus, or the antrum of Highmore. 



In the anterior part of the superior meatus is the opening of the posterior eth- 

 moidal cells, and in its posterior portion the opening of the sphenoidal sinus. 



It will hardly repay the student to undertake the dissec- 

 tion of the small vessels and nerves which are found upon 

 the walls of the nasal fossa. 



Upon the Septum. The septum is crossed from above 

 downward and forward by the nasopalatine nerve and 

 artery and the septal branch of the nasal nerve. 



Each spongy turbinated mass is provided with an artery, 

 which comes from the nasopalatine branches of the internal 

 maxillary artery. 



DISSECTION. 



On a dry skull (sawn through anteroposteriorly) locate the sphenopalatine 

 foramen. In the specimen dissect off the mucous membrane over a corres- 

 ponding area and expose the sphenopalatine foramen and the small artery and 

 nerves it transmits. 



Remove the mucous membrane carefully from the nasal fossa under the 

 cribriform plate of the ethmoid and find the nerves and arteries entering at this 

 point. 



Through the sphenopalatine foramen the nasopalatine or sphenopalatine 

 artery and nerve enter the nasal fossa. They divide into two branches, an ex- 

 ternal and internal, to the outer wall and the septum (inner wall) of the nose. 



The sphenopalatine artery is the terminal branch of 

 the internal maxillary artery and enters the sphenopalatine 



