UNIT IV. MOUTH CAVITY. DENTAL TISSUES

Lesson 7. Mouth Cavity. Grammar: Simple Tenses. Passive Voice

Exercise 1. Find the pronunciation of the following words in the dictionary and translate them.

pathway, boundary, primarily, tongue, ridge, swallow, mucosa, care, occupy, pyramid

Exercise 2. Active vocabulary. Learn the following words.

chewing - жевание

deglutition - глотание

dentition - ряд зубов

edge - край

insalivation - смачивание слюной

oropharynx - ротоглотка, мезофаринкс

pharyngeal cavity - гортанно-глоточная полость

respiration - дыхание

saliva - слюна

shape - форма

space - пространство

tear (tore, torn) - разрывать

to be subjected to - подвергаться

to extend - простираться

to grind (ground) - размалывать

Exercise 3. Translate the following word combinations before reading the text.

to pour saliva, prime organs, alveolar ridges, surrounding structures, normal physiological function, flat surface, beyond the level, final chewing

Exercise 4. Read and translate the following text into Russian.

THE MOUTH CAVITY

The oral (mouth) cavity is an oval-shaped cavity situated at the beginning of the alimentary canal. The oral cavity and oropharynx are spaces defined by both hard and soft tissue structures.

The shape of theses two spaces changes with normal physiologic function of the surrounding structures during speech, swallowing and respiration. Functionally, the oral cavity and oropharynx are the pathway that food takes, their boundaries are the muscles that move the food. Although primarily a space through which food and air travel, several structures are found in this space including the upper and lower dentition, the tongue, salivary glands, mucosal glands, mucosal tissue covering the hard palate and alveolar ridges invested by the gum.

The oral cavity is continuous with the pharyngeal cavity, a more complex and somewhat irregular space. The mouth cavity is bounded anteriorly by the lips, laterally by the cheeks, superiorly by the hard palate and inferiorly by mucosa covering the superior surface of the tongue. The secretions of the parotid, submaxillary and sublingual glands are poured into the mouth cavity and in it food is subjected to the processes of mastication and insalivation previous to deglutition. The teeth are the prime organs of mastication, implanted in the alveolar cavities. A tooth is composed of four distinct structures:

1) pulp occupying the chamber in the crown;

2) dentine which constitutes the bulk of the organ;

3) enamel which forms the protection of the crown;

4) cementum which covers the root.

The teeth of the first dentition are termed deciduous or temporary teeth. The temporary teeth are replaced by a permanent set. The anatomical divisions of the tooth are:

1) the crown or exposed part situated above the gum;

2) the root occupying the alveolar cavity of the socket;

3) the neck which is between the crown and the root.

The temporary teeth are twenty in number, ten in each jaw, namely: four incisors, two canines and four molars. The permanent teeth are thirty two in number, sixteen to each jaw, namely: incisors - four, canines - two, premolars - four, molars - six. The third or last molar is called the wisdom tooth. Wisdom teeth (one at every side of the jaw) are not a different type of teeth. They erupt between the age of 17 and 21. Wisdom teeth need special care. Sometimes they do not erupt properly and they often cause dental problems because of the difficulty to clean them well enough.

The incisors or cutting teeth occupy the anterior central part of each maxillary arch. They have rather flat surfaces, a straight sharp horizontal edge for cutting and biting food and one long, single, conical root. The function of this class of teeth is to cut the food.