184 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



remains as the salivary duct. The glands are situated among the muscles of the 

 head and throat. They should be located according to the following descriptions 

 and their ducts followed as far as practicable. There are four pairs of salivary 

 glands in the rabbit, five in the cat. The dissection should be carried out on 

 the same side of the head as that on which the muscles were dissected. 



The parotid gland is located ventrad and craniad of the base of the pinna 

 of the ear, just under the skin. Remove the skin from this region and find the 

 pinkish gland spread out under the skin anterior and ventral to the ear. Its 

 duct passes across the external surface of the masseter muscle and penetrates 

 the upper lip. The submaxillary gland has already been noted as a roundish mass 

 at the angle of the jaw near the posterior margin of the masseter. Loosen it 

 and find the duct springing from the internal surface. In the cat the beginning 

 of this duct is surrounded by the elongated sublingual gland. Trace the sub- 

 maxillary duct forward; it is accompanied in the cat by the sublingual duct. 

 The duct will be found to pass internal to the digastric muscle. This muscle 

 should be severed. The duct (or two ducts in the cat) will then be seen to pass 

 internal to the mylohyoid muscle. This in turn should be cut and the duct 

 traced forward. In the rabbit the small flattened sublingual gland will soon be 

 noted lying in the path of the submaxillary duct. The submaxillary duct (accom- 

 panied by the sublingual duct in the cat), situated just external to the lining 

 of the mouth cavity, runs forward nearly to the symphysis of the mandible and 

 then penetrates the lining. In the rabbit the sublingual gland opens into the 

 mouth cavity by several short ducts which are impractical to find. The molar 

 gland, present in the cat only, is situated between the skin and the external sur- 

 face of the mandible, just in front of the masseter muscle. It will be found by 

 deflecting the skin at this place. It opens onto the inside of the cheek by 

 several small ducts, impractical to locate. The infraorbital gland in both cat 

 and rabbit lies in the floor of the orbit and will be seen later when the eye is 

 dissected. 



b) The mouth cavity: Cut through the skin at the corners of the mouth and 

 see that the skin is well cleared away over the angles of the jaws. Cut through 

 the masseter and other muscles attached to the lower jaw at the angle of the jaws. 

 It should then be possible to pull the lower jaw down. Pry open the mouth, 

 grasp the lower jaw, and exert a strong traction. The jaw will generally yield, 

 but if it does not, the ramus of the mandible may be cut through with the bone 

 scissors. The anterior part of the cavity thus revealed is the mouth or oral cavity. 

 It is bounded by the lips and cheeks. That part of the oral cavity lying between 

 the teeth and lips is called the vestibule of the mouth. The teeth were described 

 in connection with the skull. 



The anterior portion of the roof of the oral cavity is occupied by the hard 

 palate, the posterior part by the soft palate which is very long in the rabbit. 

 The difference between the hard and soft palate should be determined by feeling. 



