PHYSIOLOGY PRACTICUMS. 



PART III. THE HEAD AND ORGANS OF SENSE. 



PRACTICUM VI. THE HEAD AND NECK OF THE CAT. 



PLATES REQUIRED, I, II, XV, XVI, XVII. 



i. If the skin of the head has been retained, remove it from the 

 left side as indicated in PI. XV, beginning with the cut edge on the 

 neck. Grasp that between the left thumb and finger and dissect it up 

 for a short distance ; then divide the skin with the scissors along the dor- 

 sal and ventral lines indicated. Lift the flap as before and continue till 

 the area is exposed. 



a. Unless the student has plenty of time the removal of the skin should be done in 

 advance by an assistant. 



b. Compare with PL XV. Bear in mind that the figure shows several parts which are 

 to be disregarded at present ; that no two individuals are absolutely identical ; that the parts 

 are probably covered by a fibrous sheet or FASCIA so as to be less distinctly visible than 

 on the figure. 



2. Removal of the Fascia. With the forceps lift the fascia at any 

 point and try to tear it off with the tracer ; if compelled to use the scal- 

 pel or scissors, be very careful not to cut anything but the fascia. The 

 JUGULAR VEIN can probably be recognized from containing some blood. 



3. The Parotid Gland. So much of the PAROTID GLAND as may 

 remain lies dorso-cephalad of the U-shaped loop of the jugular. Along 

 a line between the parotid and the angle of the mouth look carefully for 

 the DUCT OF STENO, the excretory duct of that gland ; there are two or 

 three nerves that might be mistaken for the duct, but they are solid and 

 do not join the gland by three or four roots. At the distance of about 1 

 cm. from the angle it pierces the cheek to open into the mouth opposite 

 the largest of the teeth in the maxilla (upper jaw) the third from the ca- 

 nine or eye tooth ; see PI. XVII, where a bristle is in the duct. 



a. With the scissors cut through the cheek near the mandible ; 

 reflect the flap dorsad ; pull upon the duct gently and this will indicate 

 the location of the papilla through which it opens. 



4. 7^e Submaxillary Gland. Dissect off the parotid; this will 

 more fully expose the SUBMAXILLARY GLAND which lies in the loop of the 

 jugular vein ; its duct opens in the floor of the month (See PL XVII, 

 Ductus Wharton) but time will not permit the examination of it, or of 

 the sublingual and molar glands ; Anatomical Technology, 302. Just 

 cephalad of the submaxillary and separated from it by the jugular are 

 one or two LYMPHATIC GLANDS. 



5. The Eyelids. Slit the skin at the lateral angle of the eye so as 

 to permit the wide separation of the lids. Note (a) the large size of the 



