Maxillary sinus

Question 1

What is the definition of maxillary sinus?

Answer 1

largest bilateral air sinus in the skull bones and situated in the body of the maxilla

Question 2

What is the development of maxillary sinus?

Answer 2

• it begins the development at 3MIU as bilateral invagination of the mucous membrane of the middle
  nasal meatus
• in newborn, it measures 8 x 4 x 6 mm and enlarges by pnemnatization and reaches its full development when the permanent dentition is completed (may
  expand throughout life)
• molar roots are commonly related to maxillary sinus, then the premolars and rarely the canine (6, 7, 5, 4, 8, 3)

Question 3

What is the anatomy of maxillary sinus?

Answer 3

• variable in size, shape and position from one individual to another and
  also in the two sides of the same individual
• it is pyramidal in shape
• it opens in the nasal cavity by the ostium maxillare which is found in a recess called Hiatus semilunaris in the middle nasal meatus
• the location of the opening is not favorable for drainage
• the average capacity of the maxillary sinus = 15 mL
• maxillary sinus may have septa that divide it
• the extension of the floor of the maxillary sinus into the alveolar process may reach an extent that the sinus floor may be found not only between the roots
  of adjacent teeth but also sometimes between the roots of individual tooth so that the root apices protrude into the sinus cavity and the sinus floor is elevated
  into spots to accommodate the protruding roots
• sometimes there are openings in the sinus floor, and the roots protrude through the openings into the sinus cavity
• the roots will be separated from the sinus cavity by only the soft tissue that is composed of periodontal ligament of the root
  and the mucous membrane lining the sinus
• the floor of the sinus may be at
  the same level, lower or higher level than the nasal floor

Question 4

What are the relations of maxillary inus?

Answer 4

• base: lateral wall of the nasal cavity
• apex: extends to zygomatic process of maxilla
• anterior wall: facial surface of maxilla
• posterior wall: infra-temporal surface of maxilla
• roof: floor of orbit
• floor: the alveolar process of maxilla

Question 5

What are the average dimensions of maxillary sinus?

Answer 5

• transversely = 2.3 cm
• anteroposteriorly = 3.4 cm
• vertically = 3.3 cm

Question 6

The maxillary sinus enlarges when it expends into…?

Answer 6

• frontal process
• zygomatic process
• zygomatic bone
• maxillary tuberosity
• alveolar process

Question 7

What is the epithelium of maxillary sinus?

Answer 7

• lined by mucous membrane where its epithelium is pseudostratefied columnar ciliated epithelium with goblet cells
• the pseudostratefied ciliated epithelium: single raw of
  columnar cells resting on basement membrane
• the nucleus presents in the base of the cell (the broadest part) and due to crowding the cells appear in many levels
• cilia which is composed of 9+ 1 pairs of microtubules and
  attached to the cell by basal bodies
• cilia in the free surface (its movement is not under nervous control, but they are automatically function)
• goblet cells looks like a wine-glass, consists of swollen apical end (ovoid in shape) and a short stalk-like basal end that rest on the basement membrane and contain the nucleus - the goblet cell is a unicellular gland secretes its mucin secretion by rupturing the cell membrane which again regenerate (apocrine gland)

Question 8

What s the lamina propria of maxillary sinus?

Answer 8

• formed of loose collagen fibers with few elastic fibers
• it is moderately vascular
• mixed glands present around the opening
• no submucosa present and the lamina propria fused with periostium of the underlying bone

Question 9

What are the functions of maxillary sinus?

Answer 9

• warming and moistening the inhaled air
• mportant for vocalization and phonation
• lighten the weight of the skull

Question 10

What are the clinical considerations of maxillary sinus?

Answer 10

• periapical infection in teeth related to the floor of the sinus could be a cause of sinus infection
• infection of the sinus leads to referred pain to the teeth related to it due to the close relation of the superior alveolar nerve to the sinus floor
• root may be forced into the sinus during extraction if the bone of the sinus floor is thin