1. ANATOMY OF
PARANASAL SINUSES

2. Introduction
 Air-containing spaces
 4 on each side
 Clinically:
a. Anterior : Maxillary, frontal, anterior ethmoidal
(middle meatus)
b. Posterior: Posterior ethmoidal (superior
meatus) and sphenoidal (sphenoethmoidal
recess)
 Function: Makes skull lighter; Adds
resonance

5.  Rudimentary /absent at birth
 Enlarges 6-7 years
 Development: outpouchings from mucous
membrane of lateral wall of nose.

6. Frontal Sinus
 Loc: Btw inner and outer tables of frontal
bone; above and deep to supraorbital margin
 Asymmetric
 Bony septum thin & oblique
 32x24x16mm
 Better developed in males.

7. Opens into Middle meatus
Relations:
 Ant : Skin over forehead
 Posterior: Meninges + frontal lobe of brain
 Inf: Orbit + contents
 Drains into Frontal recess
 Arterial supply: Supraorbital artery
 Venous Drainage: Supraorbital and superior
ophthalmic veins
 Lymphatic: Submandibular nodes
 Nerve: Supraorbital nerve

9. Maxillary Sinus
 Lies in body of maxilla
 Largest; first to develop
 Pyramidal; Base : med towards lat wall of nose;
apex: lat in zygomatic process of maxilla
 Opens into middle meatus (lower part of hiatus
semilunaris)
 Relations: Ant. Wall- Formed by facial surface of
maxilla, related to soft tissues of cheek
 Post. Wall- infratemporal and pterygopalatine
fossa

10.  Medial wall- middle and inferior meatuses. At
places uncinate process, ant and post
fontanelle and inferior turbinate
 Floor-Alveolar and palatine processes of
maxilla
 Roof- Floor of orbit
 3.4x2.5x3.5cm
 Arterial: Facial, infraorbital, greater palatine
arteries
 Venous: facial vein, pterygoid plexus
 Lymphatic: Submandibular nodes
 Nerve: Infraorbital, ant, middle, post alveolar
nerves

11. Ethmoidal Sinus
 Numerous (3-18)
 Lie within labyrinth of ethmoid bone
 Relations:
 Above: orbital plate of frontal bone
 Behind: Sphenoidal conchae+ orbital process of
palatine
 Ant: lacrimal bone
 Divided into anterior, middle and posterior
groups.

12.  Anterior: 1-11; opens to ant part of hiatus
semilunaris; Ant ethmoidal nerve + vessels;
lymph – submandibular nodes
 Middle: 1-7; opens to middle meatus; Post
ethmoidal nerve+ vessels+ orbital branches of
pterygopalatine ganglion; SM nodes
 Posterior: 1-7; opens to sup meatus; Post
ethmoidal nerve + vessels; orbital branches of
pterygopalatine ganglion; Retropharyngeal
nodes.

14.  Important cells in anterior group- Agger nasi
cells, ethmoidal bulla, supraorbital cells,
frontoethmoid cells, Haller cells
 Important cell in posterior group-
Sphenoethmoid or Onodi cell

15. Sphenoidal Sinus
 Within body of sphenoid bone
 Separated from each by thin bony septum
 Asymmetric
 Opens to shpenoethmoidal recess
 Relations:
 Sup: Optic chiasma+ hypophysis cerebri
 Lat: int carotid artery+ cavernous sinus

16.  Arterial supply: Post ethmoidal + int carotid
 Venous: Pterygoid venous plexus + cavernous
sinus
 Lymph: Retropharyngeal nodes
 Nerve: Post ethmoidal nerve+ pterygopalatine
ganglion branches.

18. Development and growth of
PNS
Sinus Status at birth Growth First radiologic
evidence
Maxillary At birth; Vol:6-
8mL
Rapid growth
from birth-3years;
from 7-12years.
4-6months after
birth.
Ethmoid At birth;
Ant grp:5x2x2mm
Post grp:5x4x2
Reaches adult
size by 12 years.
1 year
Frontal Not present Invades frontal
bone at 4 years.
Increases until
teens. Till 20y.
6 years.
Sphenoid Not present. Reach sella
turcica 7years,
dorsum sellae late
teens,
basisphenoid
4 years.

19. Clinical Aspects
 Acute Sinusitis
 acute inflammation of sinus mucosa.
 Most common:
Maxillary>ethmoid>frontal>sphenoid
 Can be open/closed type- drainage of the
inflammatory products into nasal cavity.
 Aetiology:
 Exciting causes: Nasal infections, swimming and
diving(bacteria, chlorine), trauma, dental
infection(Max Sinus; molar/pre-molar tooth
extraction)

20.  Predisposing causes:
 Local: obstruction to sinus ventilation and drainage
(DNS, nasal packing, hypertrophic turbinates, nasal
polypi, structural abnormalities of ethmoidal air cells,
neoplasm)
 Stasis of secretions in nasal cavity: adenoids, choanal
atresia, cystic fibrosis
 Previous attacks of sinusitis
 General
 Environment:pollution, smoke, dust
 Poor general health: exanthematous fever, nutritional
deficiency, systemic disorder

21.  Chronic Sinusitis
 Sinus infection lasting for months/years
Complications of sinusitis
 Local:Mucocele, mucous retention cyst,
osteomyelitis
 Orbital: Preseptal inflm edema of lids,
subperiosteak abscess, orbital cellulitis, orbital
abscess, superior orbital fissure syndrome
 Intra-cranial: Meningitis, extradural abscess,
subdural abscess, brain abscess, cavernous sinus
thrombosis
 Descending infections
 Focal infection.

22. Neoplasms of PNS
 Benign: Osteomas, fibrous dysplasia, ossifying
fibroma, ameloblastoma
 Malignant:Common
Mostly Maxillary>ethmoid>frontal>sphenoid.
80% squamous cell type. Rest adenocarcinoma,
adenoid cystic carcinoma, melanoma, sarcoma.

23. Thank you