For medico By medico

1. PARANASAL AIR SINUS
-Amarnath.S
1st year MBBS

2.  Paranasal air sinuses are air filled cavities in the paranasal bones,such as frontal ,ethmoid,sphenoid and
maxilla
Classification:
 4-Paranasal air sinuses
Frontal
Ethmoidal
Sphenoidal
Maxillary

3.  Clinically these sinuses are divided into two groups,
Anterior group: frontal , anterior and middle ethmoidal,and maxillary sinus.They drain into
middle meatus.
Posterior group: posterior ethmoidal, sphenoid sinus . They don’t drain into middle meatus.

4.  FUNCTIONS:
✓ make skull lighter
✓ Add resonance to voice
✓ Humidify the air during inspiration
✓ Provide adult shape to facial skeleton

5. MAXILLARY AIR SINUSES
 LOCATION:
It is the largest paranasal air sinus located in the body of maxilla.
 BOUNDARIES:
Apex- directed towards Zygoma and often extends into zygomatic bone
Base- formed by lateral wall of nasal cavity.
Roof - formed by floor of the orbit
Floor- formed by alveolar process of the maxilla . It lies about 1cm below the level of
floor of the nose
-The roots of maxillary teeth , particularly 1st two molars often protrudes into the floor
of maxillary sinus

6.  Anterior wall is formed by anterior
surface of body of maxilla and it is
related to infraorbital plexus of
nerves .
 Posterior wall is formed by
infratemporal surface of the maxilla.
 Maxillary sinus drains in middle
meatus of nose in the posterior part
of hiatus semilunaris.

8.  ARTERIAL SUPLLY:
By anterior,middle,and posterior superior alveolar arteries from maxillary and
Infraorbital arteries
 VENOUS DRAINAGE:
into facial vein and pterygoid plexus of veins
 LYMPHATIC DRAINAGE:
The sinus drains into submandibular lymph node.
 NERVE SUPPLY:
Maxillary sinus supplied by anterior, middle,and posterior superior alveolar
nerves from the maxillary and infraorbital nerves.

9.  DEVELOPMENT:
It is the 1st paranasal air sinus to develop.It develops in the fourth month of IUL.
It is rudimentary at birth, grows rapidly during 6-7 years of life .
Fully developed after the eruption of permanent teeth.

10. APPLIED ANATOMY
 MAXILLARY SINUSITIS:
Maxillary sinus is most commonly
infected because its ostium is located near the roof ,
which hampers its drainage .The infection may reach the
sinus either from nasal cavity or from caries of the upper
molar teeth.
 REFERRED PAIN:
Pain of maxillary sinus is referred to upper
teeth due to same nerve supply(Maxillary nerve)

11.  Surgically, Maxillary sinus is drained by two ways:
Antral puncture- by using trocar and canula which are
passed below the inferior nasal concha in an outward and
backward direction.
Caldwell –Luc operation- fenestrating the antrum through
Canine fossa in the gingivolabial sulcus

12.  CARCINOMA OF MAXILLARY SINUS: It arises from mucous lining of the sinus. The signs and
symptoms produced by invasion of carcinoma.
Upward invasion into the orbit displaces eyeball causing proptosis(protrusion of eyeball)
diplopia(double vision).
Downward invasion into the floor produces visible bulge of palatal roof of the oral cavity.
Medial invasion into nasal cavity cause obstruction and epistaxis(nosebleed) . The obstruction
of nasolacrimal duct in this wall causes epiphora (overflow of tears).
Lateral invasion produces swelling on the face and palpable mass in gingivolabial fold.
Backward invasion involves palatine nerves leading to severe pain in upper teeth.

13. ETHMOIDAL SINUSES
 Made up of no. of air cells present within the labyrinth of ethmoidal bone and they are located
between upper part of lateral nasal wall and orbit.
 3 groups
Anterior, consists upto 11 cells, supplied by anterior ethmoidal nerve and vessels.Its
lymphatics drains into submandibular nodes.
Middle, consists of 1-3 cells, supplied by anterior ethmoidal nerve and vessels and orbital
branches of pterygopalatine ganglion. Lymphatics drains into Submandibular nodes .
Posterior, consists of 1-7 cells, supplied by posterior ethmoidal nerves and vessels and
orbital branches of pterygopalatine ganglion. Lymphatics drains into retropharyngeal nodes.
 Anterior and middle ,drains into middle meatus.
 Posterior drains into posterior part of superior meatus.

14.  CLINICAL ANATOMY:
ETH MOIDAL SINUSITIS: Often associated with
infection of other sinuses. Pain is localised over bridge of the
nose medial to the eye.
ORBITAL CELLULITIS: Ethmoidal sinus seperated from
medial wall of orbit only by very thin plate of bone called
lamina papyracea, so infection spread easily into the orbit
and produces ORBITAL CELLULITIS.

15.  REFERENCE:
BD CHAURASIA’S HUMAN ANATOMY (8TH EDITION)
VISHRAM SINGH TEXT BOOK OF ANATOMY (3TH EDITION)

16. Thank you