Anatomy of the para nasal sinuses. Frontal, sphenoid, Ethmoid, and maxillary. Infections and management of Sinusitis

1. GROUP PRESENTATION
GROUP MEMBERS
1. SSENYOMO DERRICK
2. MANGOBE DAGLOUS
3. CHEPTEGEI SHERY
4. NANSASI SHIRAT
5. ASIIMWE VICTOR

2. TASK
• ANATOMY OF PARA NOSAL SINUSES

3. INTRODUCTION
• Paranasal sinuses are air-containing cavities in certain bones
of skull.
• They are four on each side. Clinically, paranasal sinuses have been
divided into two groups.
• The anterior and posterior groups.

4. CON’T
1. Anterior group,
• This includes maxillary, frontal and anterior ethmoidal.
• They all open in the middle meatus and their ostia lie anterior to
basal lamella of middle turbinate.
2. Posterior group.
This includes posterior ethmoidal sinuses which open in the superior
meatus and the sphenoid sinus which opens in sphenoethmoidal
recess.

5. MAXILLARY SINUS(ANTRUM OF HIGHMORE)
• It is the largest of paranasal sinuses and occupies the body of maxilla.
• It is pyramidal in shape with base towards lateral wall of nose and
apex directed laterally into the zygomatic process of maxilla and
sometimes in the zygomatic bone itself.
• On an average, maxillary sinus has a capacity of 15 mL in an adult. It is
33 mm high, 35 mm deep and 25 mm wide.

6. Coronal section showing relationship of maxillary
and ethmoidal sinuses to orbit and the nasal cavity

7. RELATIONS
• Anterior wall is formed by facial surface of maxilla and is related to
the soft tissues of cheek.
• Posterior wall is related to infratemporal and pterygopalatine fossae.
• Medial wall is related to the middle and inferior meatuses. At places,
this wall is thin and membranous. It is related to uncinate process,
anterior and posterior fontanelle, and inferior turbinate and meatus.
• Floor is formed by alveolar and palatine processes of the maxilla and
is situated about 1 cm below the level of floor of nose.

8. CON’T
• Usually it is related to the roots of second premolar and first molar
teeth.
• Depending on the age of the person and pneumatization of the sinus,
the roots of all the molars, sometimes the premolars and canine, are
in close relation to the floor of maxillary sinus separated from it by a
thin lamina of bone or even no bone at all.
• Oroantral fistulae can result from extraction of any of these teeth.
Dental infection is also an important cause of maxillary sinusitis.
• Ostium of the maxillary sinus is situated high up in medial wall and
opens in the posteroinferior part of ethmoidal infundibulum into the
middle meatus.

9. CON’T
• It is unfavourably situated for natural drainage. An accessory ostium
is also present behind the main ostium in 30% of cases.
• Roof of the maxillary sinus is formed by the floor of the orbit. It is
traversed by infraorbital nerve and vessels

10. FRONTAL SINUS
• Each frontal sinus is situated between the inner and outer tables of
frontal bone, above and deep to the supraorbital margin.
• It varies in shape and size and is often loculated by incomplete septa.
• The two frontal sinuses are often asymmetric and the intervening
bony septum is thin and often obliquely placed or may even be
deficient.
• . Frontal sinus may be absent on one or both sides or it may be very
large extending into orbital plate in the roof of the orbit.
• Its average dimensions are: height 32 mm, breadth 24 mm and depth
16 mm (remember code 8, i.e. 8 × 4, 8 × 3 and 8 × 2).

11. • Anterior wall of the sinus is related to the skin over the forehead.
• inferior wall, to the orbit and its contents;
• posterior wall to the meninges and frontal lobe of the brain.

12. CON’T
• Drainage of the frontal sinus is through its ostium into the frontal
recess.
• In fact frontal sinus, its ostium and the frontal recess form an hour
glass structure.
• Frontal recess is situated in the anterior part of middle meatus and is
bounded by the middle turbinate (medially), lamina papyracea
(laterally), agger nasi cells (anteriorly) and bulla ethmoidalis
(posteriorly).
• It may be encroached by several anterior ethmoidal cells, which may
obstruct its ventilation and drainage and lead to sinusitis

13. CON’T
• . Frontal recess drains into the infundibulum or medial to it,
depending on the superior attachment of the uncinate process.
• Due to encroachment of small air cells in the frontal recess, the
drainage pathway may be reduced to a straight or more often
tortuous pathway which was earlier called nasofrontal duct. It is an
erroneous term as no true duct exists.

14. ETHIMOIDAL SINUS(ETHIMOID HAIR CELLS)
• Ethmoidal sinuses are thin-walled air cavities in the lateral masses of
ethmoid bone.
• Their number varies from 3 to 18.
• They occupy the space between upper third of lateral nasal wall and
the medial wall of orbit.
• Clinically, ethmoidal cells are divided by the basal lamina into an
anterior ethmoid group which opens into the middle meatus and
posterior ethmoid group which opens into the superior meatus and
into supreme meatus, if that be present.

15. CON’T
• Roof of the ethmoid is formed by medial extension of the orbital plate
of the frontal bone, which shows depressions on its undersurface,
called fovea ethmoidalis.
• The lateral wall is formed by a thin plate of bone called lamina
papyracea

16. Anterior Group
Important ethmoid cells in the anterior group include:
1. Agger nasi cells – present in the Agger nasi ridge.
2. Ethmoid bulla – forms the posterior boundary of the hiatus
semilunaris.
3. Supraorbital cells.
4. Frontoethmoid cells – situated in the area of the frontal recess and
may encroach the frontal sinus.
5. Haller cells – situated in the floor of the orbit.

17. POSTERIOR GROUP
• The posterior group of ethmoid sinuses lies posterior to the basal
lamina of middle concha.
• They are 1–7 in number and open into superior meatus or in the
supreme meatus, when present.
• One important cell of this group is sphenoethmoid cell, also called the
Onodi cell. It is the most posterior cell of this group and extends along
the lamina papyracea, lateral or superior to the sphenoid and may
extend 1.5 cm behind the anterior face of sphenoid.
• Optic nerve and sometimes the carotid artery are related to it laterally
and are in danger during endoscopic surgery.
• At birth anterior ethmoids are 5 × 2 × 2 mm and posterior ethmoids are
5 × 4 × 2 mm. They attain their adult size by the 12th year.

18. SPHENOID SINUS
• It occupies the body of sphenoid. The two, right and left sinuses, are
rarely symmetrical and are separated by a thin bony septum which is
often obliquely placed and may even be deficient (compare frontal
sinus).
• Ostium of the sphenoid sinus is situated high up in the anterior wall
and opens into the sphenoethmoidal recess, medial to the superior or
supreme turbinate.
• It may be slit like, oval or round and can be seen endoscopically. In
adults, it is situated about 1.5 cm from the upper border of choana.
• The average distance from the anterior nasal spine to the ostium is
about 7 cm

19. CON’T
• An adult sphenoid sinus is about 2 cm high, 2 cm deep and 2 cm
wide, but its pneumatization varies.
• In some cases pneumatization may extend into greater or lesser wing
of sphenoid, pterygoid or clivus, i.e. basilar part of occipital bone.

20. Relations of the Sphenoid Sinus
• Lateral wall of the sphenoid is related to the optic nerve and
carotid artery. The opticocarotid recess can be seen in between the
two.
• It may extend laterally when the anterior clinoid processes are also
pneumatized. Maxillary nerve may be related to lower part of the
lateral wall of sphenoid. The optic nerve and internal carotid artery
are usually covered by a thin bone, but sometimes this bony covering
may be dehiscent, and then these structures lie exposed, covered
only by mucosa

21. CON’T
• Floor of the sinus is related to the Vidian nerve.
• Relation of the roof can be divided into two parts. Anterior part of
the roof is related to the olfactory tract, optic chiasma and frontal lobe,
while posterior part is related to the pituitary gland in the sella turcica
and laterally to the cavernous sinus.
• Posterior wall of the sphenoid forms the clivus.
• Relations of the sphenoid sinus are important in endoscopic skull
base surgery

22. Coronal section of sphenoid sinuses

23. Relations of sphenoid sinus

24. MUCOUS MEMBRANE OF PARANASAL SINUSES
• Paranasal sinuses are lined by mucous membrane which is continuous
with that of the nasal cavity through the ostia of sinuses.
• It is thinner and less vascular compared to that of the nasal cavity.
Histologically, it is ciliated columnar epithelium with goblet cells
which secrete mucus.
• Cilia are more marked near the ostia of sinuses and help in drainage
of mucus into the nasal cavity.

25. DEVELOPMENT OF PARANASAL SINUSES
• Paranasal sinuses develop as outpouchings from the mucous
membrane of lateral wall of nose.
• At birth, only the maxillary and ethmoidal sinuses are present and
are large enough to be clinically significant.
• Growth of sinuses continues during childhood and early adult life.
• Radiologically, maxillary sinuses can be identified at 4–5 months,
ethmoids at 1 year, frontals at 6 years and sphenoids at 4 years

27. Anterior and posterior group of sinuses.

28. LYMPHATIC DRAINAGE
• The lymphatics of maxillary, ethmoid, frontal and sphenoid sinuses
form a capillary network in their lining mucosa and collect with
lymphatics of nasal cavity. Then they drain into lateral
retropharyngeal and/or jugulodigastric nodes.