osteomeatal complex

1. Surgical anatomy of
osteomeatal complex
By :-
Dr. Arshana Tabassum
MS ENT (1ST Year)
Patna medical college

2. CONTENTS
 Definition
 Boundaries
 Parts of OMC
 Anterior and posterior OMC
 Anatomical variations

3. Osteomeatal complex
 Also known as ostiomeatal unit
or key area
or critical area
 It is final common pathway for
drainage and ventilation of
ethmoid, maxillary and
frontal sinuses.

4. Osteomeatal complex contd…..
 It is a functional concept rather than an anatomic structure with defined
boundaries.
 Goal of naming this area is to emphasize the concept that inflammation in
OMC can lead to anatomic and functional obstruction of anterior sinuses.
Any of these cells, clefts, ostia, recesses or cavities may be affected by a
pathological process, thereby contributing to the symptoms and
pathophysiology of sinusitis.
 Medical and surgical strategies are devised to eliminate OMC obstruction
and restore sinonasal function.
 For performing FESS the knowledge of OMC anatomy is also very important.

5. Boundaries
.
When the middle turbinate is reflected medially, the borders
and components can be more readily appreciated.
Anteriorly, the unit is in open communication with the anterior
nasal cavity. The agger nasi and atrium of the middle meatus also
have an anterosuperior, and anterior (respectively) relations to the
complex.
Superiorly, the ostiomeatal complex (OMC) is limited by the basal
lamella.

6. Posteriorly, The basal lamella continues along the length of the
middle turbinate and consequently forms the posterior border of
the space.
Inferiorly, the ostiomeatal unit has an open communication with
the middle meatus. The drained contents of the unit will travel in
the meatus along with the superior border of the inferior concha,
which forms the floor of the middle meatus.
Medially, the complex is limited by the body of the middle
concha. Laterally, the lamina papyracea of the ethmoid sinuses
borders the complex.

8. The ostiomeatal complex is differently defined by several authors.
 Naumann H ..he was the first to develop this anatomical unit and coined the term
term osteometal complex. According to him it consists of semilunar hiatus and
middle meatus.
 Scribano et al. have defined the ostiomeatal complex as a complex including the
maxillary sinus ostium, ethmoid infundibulum and middle meatus; in other words,
as the final site of drainage from the frontal and maxillary sinuses and anterior
ethmoidal cells.
 Casiano has defined the ostiomeatal complex as the ethmoid bulla, uncinate
process and adjacent spaces and ostia draining the anterior sinuses (anterior
ethmoid sinus, frontal and maxillary sinuses).

9.  Laine & Smoker have defined the ostiomeatal complex as an aerated
channel of the middle meatus representing the final common pathway
for drainage of the maxillary and frontal sinuses and anterior ethmoid
cells, delimited by the uncinate process, ethmoidal bulla and middle
turbinate.
 Shankar et al. have defined ostiomeatal complex as a complex
including the maxillary ostium, ethmoid infundibulum, hiatus
semilunaris, middle meatus, frontal recess, ethmoid bulla and uncinate
process.
 Stammberger & Kennedy , defining ostiomeatal complex as a
functional unit of the anterior ethmoid complex representing the final
common pathway for drainage and ventilation of the frontal, maxillary
and anterior ethmoid cells.

10. The ostiomeatal complex is composed of five
structures:
 maxillary ostium:
drainage channel of the
maxillary sinus
 infundibulum: common
channel that drains the
ostia of the maxillary antrum
and anterior ethmoid air
cells to the hiatus semilunaris

11. ethmoid bulla: usually a single air cell that projects over
the hiatus semilunaris
uncinate process: hook-like process that arises from the
posteromedial aspect of the nasolacrimal duct and forms
the anterior boundary of the hiatus semilunaris
hiatus semilunaris: final drainage passage; a region
between the ethmoid bulla superiorly and free-edge of
the uncinate process

12. Showing the Osteomeatal
complex (OMC)-(a) The
OMC-small compartment
located in the region
between the middle
turbinate and the lateral
nasal wall in the middle
meatus-represents the key
region for the drainage for
the maxillary, anterior
ethmoid and frontal
sinuses

13.  Some authors divide this osteomeatal complex into anterior and
posterior.
 Space infront of basal lamella is anterior osteomeatal complex, while the
space behind the basal lamella of middle turbinate containing the
posterior ethmoidal cells is referred to as the posterior ethmoidal
complex, thus recognising the importance of basal lamella as an
anatomical landmark to the posterior ethmoidal system.
 the anterior and the posterior osteomeatal complex has separate
drainage systems. So when the disease is limited to the anterior
compartment of the osteomeatal complex, the ethmoid cells can be
opened and diseased tissue removed as far as the basal lamella, leaving
the basal lamella undisturbed minimising the risk during surgery.

17. Common anatomical variations of the OMC
 concha bullosa
 paradoxical middle turbinate,
 uncinate process hypertrophy and pneumatization,
 hypertrophy of the bulla ethmoidalis and the agger
nasi cell
 presence of the maxilo-ethmoidal cell (Haller’s cell)

18. Concha Bullosa & paradoxical middle
turbinate
The middle turbinate may be congenitally filled with air
(pneumatized). This variation is referred as a concha
bullosa.
Also, there are also instances where the middle turbinate
develops in a sigmoid shape – with a superior convexity and
an inferior concavity. This condition is referred to as
a paradoxical middle turbinate.

20. Uncinate process deviation
The uncinate process may deviate from its typical
posteroinferior course and arise in a medial fashion that
obstructs the middle meatus and the ethmoid infundibulum.
In cases where hypoplastic maxillary sinuses are present,
lateral elevation of the uncinate process until it fuses with the
medial orbital wall can impede the integrity of the orbit.

21.  Based on the ethmoid bulla’s configuration and size and the orientation of the
uncinated process, the abnormalities in OMC are classified into six types
Earwaker defined that as follows:
type 1: vertical UP orientation and enlarged or prolapsed ethmoid bulla,
type 2: vertical UP orientation and normal ethmoid bulla,
type 3: vertical UP orientation and absent or hypoplastic ethmoid bulla,
type 4: horizantal UP orientation and enlarged or prolapsed ethmoid bulla,
type 5: horizantal UP orientation and normal ethmoid bulla,
type 6: horizantal UP orientation and absent or hypoplastic ethmoid bulla
UP orientation ethmoid bulla
Type 1 Vertical enlarged or prolapsed
Type 2 Vertical Normal
Type 3 Vertical absent or hypoplastic
Type 4 Horizantal enlarged or prolapsed
Type 5 Horizantal Normal
Type 6 Horizantal absent or hypoplastic

22. A 20-year-old male with type 1 UP
insertion. Coronal CT scan shows that UP is
attached (straight arrow) to the laminae
papyracea (asteriks) on the left.
A 38-year-old male with type 2 UP insertion. (A, B) Two consecutive
cross-sections on coronal CT. Left uncinate process is attached (A,
arrow) to the posterior agger nasi cell (B, arrow)

23.  The superior attachment of the uncinate process have
implications on drainage of frontal sinuses.
 If attached to skull base
middle turbinate
 If attaches laterally to orbit ___
drains into superior aspect
of infundibulum
drains medial to uncinate
process into middle meatus

24. Curved tip of UP
 The UP can show a set of rotation and attachment variations. The most
commonly observed variation is a medially oriented UP. If it moves anteriorly and
exits from the middle meatus, it is called ‘Kaufmann’s double middle turbinate’.
 The horizontal and vertical orientation of UP is determined by adjacent
structures:
 ethmoid bulla affecting frontal OMU drainage and middle concha.
 Horizontal UP is always related to an enlarged ethmoid bulla. The
UP can also take the form of a hook or can be pneumatized.

25. A 41-year-old female with horizontal and vertical UP. (A) The horizontal orientation
of the left uncinate process (straight arrow) is accompanied by a large ethmoid bulla
(dotted arrow) on the coronal CT. (B) In a different case, both uncinate processes
seem to be localized vertically.

26.  The aeration of UP is called uncinate bulla.
 Even though the mechanism of occurrence is not sufficiently known, it is predicted that the
agger nasi cells stem from the growth of the UP’s frontmost and uppermost section
towards the inside.
 The uncinate bulla are considered to be a variation that can alter the ventilation through
the infidibulum, anterior ethmoid cells and frontal recess.
 It increases the wideness of the uncinate, so it constitutes to be potentially dangerous for
the infundibulum. Narrowness in the infundibulum is of clinical significance, since it can
disrupt ventilation in the frontal ethmoid cells and the frontal recess region. It can cause
significant deterioration in OMU function by acting functionally like a concha bullosa or a
widened ethmoid bulla. As it is in the uncinate bulla and haller cells, the pathological effect
should be considered in cases where the number of combinations of anatomical variations
is higher.
Uncinate bulla

27. A 44-year-old female with uncinate bulla. (A) Coronal CT image shows that both uncinate
processes are pneumatized (straight arrow). (B) In a different case, bilateral uncinate bulla
variation (straight arrow) causes significant narrowing in the ostiomeatal unit.

28. Bifid UP
A 23-year-old male with bifid uncinate process. Coronal CT
demonstrates (A) bilateral and (B) right-sided bifid UP (straight arrow)
in different cases.

29. Atelectatic UP
Sometimes, UP’s free end shows hypoplastic development and attaches to orbital medial wall
inferior section of lamina paprisea. This condition is called atelectatic UP . Generally, it is seen
together with an opacified hypoplastic maxillary sinus . This variation is very important in the
cases where anterior endoscopic sinus surgery is applied. If it is not defined radiologically, it can
cause important complications posing a great danger for the orbital and optic nerve during
unsinectomy.
•NCBI
•NCBI
A 52-year-old male with atelectatic uncinate
process. Opacified hypoplastic maxillary sinus
antrum (dotted arrow) is shown together with
UP (straight arrow) attached to the inferomedial
orbital wall on coronal CT image.

30. Hypertrophy of the Bulla Ethmoidalis and the
Agger Nasi Cell
 Ethmoid bulla is large anterior ethmoid air cells found in many people
 The degree of pneumatization may be highly variable, from a giant ethmoid bulla that
pushes the UP medially.
 Enlarged ethmoid bulla includes cells that grow up to the ethmoid ceiling superiorly,
basal lamella of the middle concha posteriorly, and lamina paprisea laterally.
 The relationship of ethmoid bulla with lamina papyracea and lateral, and the relationship
of frontal cranial fossa in superior with base should be clarified in preoperative CT.
 Ethmoid bulla is a reliable surgery marker point because it is the highest and the most
constant anterior ethmoid cell.

31. The giant ethmoid bulla may enlarge to narrow or obstruct the
middle meatus and infundibulum

34.  Blood supply ___ mainly by anterior ethmoidal artery which is
the branch of ophthalmic artery ( br of internal carotid artery)
 Venous drainage _____mainly by anterior ethmoidal vein.

35. Thank you