46 THE THORACIC VISCERA, BUCCAL CAVITY, 



between the lower turbinate and the palate, while the 

 olfactory passages proper lie between the upper 

 ethmoidal turbinates. 



a. The Schneiderian Membrane is the mucous 

 membrane covering the upper turbinates. It is usually 

 of a darker color than the rest of the nasal mucous 

 membrane, and contains the end organs or cells of 

 the olfactory nerve-fibres. 



5. The Salivary Glands. 



Dissect on the side not previously used. No especial 

 directions are required. 



a. The Parotid Gland is not very prominent in the 

 dog. It lies posterior to and somewhat in front of 

 the ear, and forms a somewhat indefinite pinkish mass. 



b. Stenson's Duct, the duct of the parotid, arises 

 from the ventral margin of the gland, runs across 

 the middle of the masseter muscle, bends inward at 

 the border of the muscle, and opens into the mouth by 

 a small aperture on the inside of the cheek opposite 

 the posterior portion of the last premolar of the 

 maxilla. Insert a probe into the duct and demon- 

 strate the opening into the mouth. 



c. The Sub-maxillary Gland forms on each side 

 a compact mass lying just posterior to the angle of 

 the mandible and concealed by connective tissue, 

 which must be cleared away. 



d. Wharton's Duct. The duct of the sub-maxil- 

 liary will be exposed best if the attachment of the 

 digastric (see page 65) to the mandible is cut, and 

 this muscle reflected backward as far as possible. If 

 the thin sheet of muscle (mylo-hyoid) lying in the 

 floor of the mouth is now carefully cut the duct will be 

 exposed, and can be traced back to the gland and for- 

 ward to its opening upon the floor of the mouth. 



