430 THE IIORSE. 
used in the digestive process. ‘The earthy phosphates in the saliva collect 
around the teeth, being held together by animal matter, and forming what 
is known as tartar. 
THE PHARYNX AND WSOPHAGUS receive the food from the back of the 
mouth and convey it to the stomach. The former is a funnel-shaped bag, 
lined with mucous membrane, and covered by the three constrictors of 
the pharynx, which suspend it to the os hyoides and palate bones. Pos- 
teriorly it lies close to the spine, being only separated by a thin layer of 
muscles (see anterior cervico-occipital region). Anteriorly and superiorly 
it opens into the mouth and nasal cavities, from which it is separated by 
the soft palate and epiglottis. Posteriorly and superiorly the eustachian 
tubes open into it bell-mouthed ; and inferiorly it contracts to connect 
A 
Hig. 3.—-lHE STOMACH AND SPLEEN. 
1. Pylorus (tied with a ligature). 6. 6. 6. The lesser curvature. 
2. 2. The pyloric sac. 7. 7. The spleen. ; 
3. Cardiac orifice (tied). 8. 8. 8. Omentum attaching the stomach to the 
4. 4. The cardiac sac. spleen. 
5. 5. 5. The greater curvature. 
itself with the esophagus. The velum-palati is so arranged as to act as a 
valve in preventing the entrance of air into the larynx through the mouth, 
but in the act of coughing the latter is convulsively drawn down, and the 
valve ceases to cover its orifice, so that forcible expiration can then be 
effected. i 
THE G@SOPHAGUS commences where the pharynx ends, being at first 
placed behind the larynx and in front of the cervical vertebre. It soon 
inclines to the left, and continues to occupy that position as regards the 
trachea all down the neck, entering the thorax above it. From the first 
