Anatomy of Paranasal Sinuses

1. ANATOMY OF PARANASAL SINUSES

2.  There are 4 Paired Paranasal Sinuses; Air Containing spaces
1. Anterior Group of Sinuses
Frontal
Anterior Ethmoidal
Maxillary
All of these open into the middle meatus anterior to the middle
turbinate.
2. Posterior Group of Sinuses-
Posterior Ethmoidal (opens in the superior meatus)
Sphenoid (opens in sphenoethmoidal recess)

3. FUNCTION
 Lighten skull bones
 Add resonance to speech
 Vital role in conditioning the inspired air
 Thermal insulators
 Extra surface for olfaction
 Local immunological defence
 Buffers against trauma to brain

5. MAXILLARY SINUS
 (Antrum Of Highmore)
 Largest sinus, average 15 ml capacity
 Pyramidal in shape
 Boundaries-
1)Roof- Floor of the orbit
2) Medial wall- middle and inferior meatuses
3) Floor- maxilla ( palatine and alveolar processes)
4) Posterior wall- infratemporal and pterygopalatine fossae
5) Anterior wall - facial surface of maxilla
6) Lateral wall- Zygomatic process of maxilla or Zygomatic bone itself

8. ETHMOIDAL SINUS
• Group of 3-18 thin walled air cavities in the lateral masses of ethmoid bone
• Openings-
• 1) Anterior ethmoid- Middle meatus
• 2) Posterior ethmoid- Superior meatus and into supreme meatus
• Roof - Medial extension of the orbital plate of the frontal bone
• Lateral - Lamina papyracea
• Anterior Group: 1. Agger nasi cells
2. Ethmoid bulla
3. Supraorbital cells
4. Frontoethmoid cells
5. Haller cells
• Posterior Group: Onodi cell (sphenoethmoidal cell)

11. SPHENOID SINUS
 Occupies the body of the Sphenoid. Right & left sinus separated by thin bony septum.
 Ostium of the sinus opens within sphenoethmoidal recess, medial to the superior turbinate.
 Volume of an adult spenoid sinus: 2 cm x 2 cm x 2 cm
 Radiologically, sphenoid sinuses can be identified at 4 years of age
 Associated with the least common sinusitis.
 Mucocilliary clearnace is towards the ostium into the sphenoethmoidal recess
 Blood supply - sphenopalatine artery and posterior ethmoidal artery.
 Nerve supply - first and second divisions of the trigeminal nerve.
 Relations:
1) Laterally: Optic nerve, Maxillary nerve, Internal carotid artery
2) Inferiorly: Vidian nerve.
3) Superiorly: Pituitary, Olfactory nerve.
4) Posteriorly it forms Clivus

14. FRONTAL SINUS
 Situated between inner and outer tables of frontal bone, above and deep to supra
orbital margin
 Relations:
Anterior wall - skin over the forehead
Inferior wall - orbit and its contents
Posterior wall - meninges and frontal lobe of the brain
 Drains through its ostium into the frontal recess
 Radiologically, identifiable at 6 years of age.
 Anterior ethmoidal cells may obstruct drainage into the frontal recess and cause sinusitis
 Mucocilliary clearnace is anticlockwise in the right and clockwise in the left sinuses and
though its natural ostium.
 Frontal sinus is supplied by the supraorbital and supratrochlear arteries of the
ophthalmic artery
 It is innervated by the supraorbital and supratrochlear nerves of the first division of the
trigeminal nerve

16. Lymphatic Drainage of PNS
 Lymphatics of maxillary, ethmoid, frontal and sphenoid sinuses form a
capillary network in their lining mucosa and collect with lymphatics of
nasal cavity
 They drain into lateral retropharyngeal and/or jugulodigastric nodes

17. Ventilation of PNS

18. THANK YOU