THE HEAD. 379 



IX. DISSECTION OF THE HEAD. 



Skin the head. Open the jaws, examine the mouth (pp. 379- 

 380), and with bone forceps inserted between the lower incisors 

 separate the halves of the lower jaw. With strong scissors 

 cut close to the left mandibular bone, follow its' course, and 

 remove it. Insert the bone forceps between the two nasal 

 bones and remove the left one ; then between the front incisors, 

 so as to divide the halves of the upper jaw. With strong scissors 

 cut through the soft palate and nasal cavity a trifle to the left 

 of the middle line. Cut through the hard palate, ethmoid, &c, 

 with bone forceps. In this way the left half of the skull may 

 be removed. 



Notice the cartilaginous mesethmoid plate separating the 

 right from the left nasal cavity. Carefully remove it from 

 before backwards, noticing and retaining the vascular organ of 

 Jacobson attached to its ventral surface in the first part of its 

 course. 



Sponge the turbinal bones that now lie exposed. With 

 scissors carefully expose the nasal passage and follow it back- 

 wards to the pharynx. Scrape the tongue clean, lay open the 

 pharynx, the first part of the trachea, and the oesophagus. 

 Make a drawing of this lateral dissection at least twice the 

 natural size. 



1. The roof of the mouth. 



a. The palate, or median part of the roof, is long and 



narrow, and separates the buccal from the nasal 

 cavity. Its anterior half, the hard palate, is 

 raised into hard transverse ridges, against which 

 the tongue works ; the posterior half, or the soft 

 palate, is smooth and soft, and ends behind in a 

 free notched border, nearly oppo iie the angle of 

 the jaw. 



b. The upper teeth, comprising the incisors at the 



front of the palate, and the grinders at the sides 

 opposite the junction of hard and soft palates, 

 have already been described (p. 322). 



