VII. Read and translate the text.

The Structure of the Maxilla

The bones of the face consisting of the mandible and the superior maxillary bones from much of the anterior portion of the face. The superior maxillary bones are closely knit together except the mandible which is movable. The superior maxillary bones being knit together on the median line of the face are two in number and of a very irregular form.

They occupy the anterior upper part of the face and consist of a body and processes. There are four processes which extend out from the body of the maxillae, namely the frontal process, the zygomatic process, the alveolar process, and the palatine process.

The alveolar processes of the left and right maxillae form an arch-like shape of bone that surrounds the roots of the maxillary dental arch of teeth. The roots of the teeth are embedded in individual alveoli (tooth sockets). The shape of each alveolus naturally corresponds closely with the shape of the roots it surrounds. Being the largest bones of the face except the mandible, the maxillary bones enter into the formation of three cavities, namely: the orbit, the mouth and the nares.

The body is the central part of the bone. The body is shaped like a four-sided hollow pyramid with the base oriented vertically next to the nasal cavity. Its apex extends laterally into part of the cheek bone (or zygomatic bone). The body exhibits four surfaces, namely: the external or facial, the posterior or zygomatic, the superior or orbital, and the internal or palatine.

The facial surface is directed towards and vertically and the lower border is more protruded than the upper one. This surface presents a depression just above the canine and the first bicuspid teeth. It is called the canine fossa. Above the canine fossa there is the infraorbital foramen for the nerve of the same name. The entrance to the alveolar canals where the nerves to the maxillary teeth enter the maxilla are very small foramina located posterior and superior to the third molar.

The zygomatic surface is situated posteriorly forming the anterior boundary of the zygomatic fossa. Between it and the facial surface there is a well-developed ridge extending from the molar region to the base of the zygomatic process.

The posterior surface has a bulging called tuberosity. It is connected with the palate and bounds the antrum behind. Being perforated by three or four small holes the posterior surface transmits nerves and blood vessels to the molar teeth.

The orbital surface of the maxillae forms the greater part of the floor of the orbit where an infraorbital fissure is located.

VIII. Answer the following questions.

1. How many superior maxillary bones are there?

2. Where are the superior maxillary bones knit together?

3. What part of the face do they occupy?

4. What do they consist of?

5. What cavities do the superior maxillary bones form?

6. What is the central part of the bone?

7. What form does the body of the bone have?

8. How many surfaces does the body of the bone have?

9. What is the canine fossa?

10. Where is the infraorbital foramen situated?

11. What is there on the posterior surface?