65 



CHAPTER IL 



DIGESTION. DISEASES OF TEETH. INSALIYATION. 



Mastication. Opening and closing the jaws. Lateral action in herbivora. 

 Regularity in the action of the jaws. The action slow. Peculiarity in 

 ruminants. Movement in carnivora. Action of tongue during mastica- 

 tion. Injuries to the temporo-maxillary joints. Dislocation. Open 

 joint. Diseases of the jaws. Fractures. Their consequences. Scrofu- 

 lous softening and degeneration. Fibro-plastic growths, or osteo-sarcoma. 

 Abnormal state of the teeth. Tumour on an incisor. Buck teeth. 

 'Crib- biting.' Its symptoms and prevention. Fracture and dislocation 

 of the incisors. Removal of incisors. Peculiarities and disease of the 

 molar teeth. Supernumerary teeth. Wolf's teeth. Irregularities of de- 

 velopment. Fistulas on the forehead. An instructive case in a colt. 

 Molar pressing through the palate. Irregularities in the rows of teeth. 

 Sharp edges of molars. Excess in length of molars. Caries. Deposit 

 of bone within the tooth socket. Diseases of the dental pulp and of 

 periosteum. Symptoms of disease of teeth. Operations on teeth. 

 ' Chewing a rasp.' Brogniez's instruments. Go wing's Instruments. 

 Extraction of teeth. Plugging teeth. Insalivation. Diseases of the 

 salivary apparatus. Funrtional disorders. Concretions. Parotiti/s. 

 Deglutition. 



THE jaws and teeth are disposed, as we have already 

 seen, for a very various action in carnivorous and her- 

 bivorous animals. The mouth is opened by the relaxa- 

 tion of the powerful masseters, the dropping of the lower 

 jaw in consequence of its own weight and the action 

 of the digastric muscle. In the horse, another muscle, the 

 stylo-maxillaris, aids materially in the same act. The closure 

 of the mouth is effected by muscles which are extremely 



F 



