Anatomy & Physiology of Anatomy & Physiology of PNSPNS

Dr. B. Arvind. Sangavi. M. S. ( E. N. T.)

Associate ProfessorDept Of ENT & HNS

RIMS

Paranasal sinusesParanasal sinuses

PNS are air containing cavities in the skull bones & are lined by mucosa, which drains into the nasal cavity.

Development The PNS arise as localized epithelial

invaginations or recesses of the nasal mucosa, after 2nd month.

These recesses become ostia of various sinuses

PNS GroupsAnterior group :

1. Frontal Sinus

2. Maxillary sinus

3. Anterior Ethmoidal sinus

4. Middle Ethmoidal sinus

Posterior Group :

1. Posterior Ethmoidal sinus

2. Sphenoid sinus

Sinus Anatomy Overview

Bony Structure

Sinus Drainage Schema

Osteomeatal Complex Micro architectural pathway of drainage

& anterior group of PNS, consists of narrow passage between uncinate process & bulla ethmoidalis.

This cleft comprises of ostium & frontal recess

Anatomical & pathological abnormalities in this region lead to persistent of infection & disease

Osteomeatal Complex Middle meatus , Ethmoidal infundibulum Maxillary Sinus Ostium Frontal recess Drainage

Osteomeatal Complex

Maxillary Sinus ( Antrum of Highmore)Maxillary Sinus ( Antrum of Highmore) Present at birth Pyramidal in shape 15 ml capacity Walls : Anterior,

posterior, roof & floor.

Floor is 1 cm below the level of floor of nose.

Maxillary SinusMaxillary Sinus Ostia opens into posterior part of

infundibulum middle meatus Related Structures

Fontanelles Natural ostium

Haller’s Cells &Sinusitis Osteomeatal complex

Accessory Ostium- 30% Nasolacrimal duct

Fontanelles

Nasolacrimal Duct

Frontal SinusFrontal Sinus Not present at birth,

develops at age 5 Between outer & inner

table of frontal bone Varies in size/shape Average 7 ml capacity Ostia – floor Opens into middle meatus

frontal recess, infundibulum

Frontal SinusOstiumFrontal recess Boundaries

Dumbbell shape

Sinus LateralisFrontal Bulla

Ethmoid SinusEthmoid Sinus Present at birth Occupies the med wall of

orbit & upper third of lat wall of nose

Anterior/Posterior group 3-18 air cells Antr - middle meatus Postr – superior meatus

Ethmoid Roof

•Anterior 2/3•Posterior 1/3

Keros IKeros IIKeros III

Ethmoid Cells

Supraorbital, Frontal Bulla, Concha Bullosa, Haller’s, Onodi Cells

Onodi cellOnodi cell

Onodi cell : posterior ethmoidal cells may extend lateral to sphenoid sinus where it is related to optic nerve.

Ethmoid Sinus—Related StructuresEthmoid Sinus—Related Structures

Basal Lamella of the Middle TurbinateBasal Lamella of the Middle Turbinate Three planesThree planes

Agger nasi cellAgger nasi cell Childhood sinusChildhood sinus

Ethmoid BullaHiatus SemilunarisEthmoid BullaHiatus Semilunaris Suprabullar/retrobullar Suprabullar/retrobullar Hiatus Semiluninaris/Superior recesses (Sinus Lateralis)Hiatus Semiluninaris/Superior recesses (Sinus Lateralis)

Ethmoid Infundibulum/Uncinate ProcessEthmoid Infundibulum/Uncinate Process Anterior/Posterior Ethmoid ArteriesAnterior/Posterior Ethmoid Arteries Osteomeatal complexOsteomeatal complex

Ethmoid BullaUncinate Process

Hiatus Semilunaris

Sphenoidal SinusSphenoidal Sinus Situated in body of sphenoid Two halves, separated by septa-asymmetric Drains into sphenoethmoidal recess Superior- pituitary, optic chiasma, olfactory

tract, frontal lobe Inferior- nasopharynx Anterior- nasal cavity Lateral- cavernous sinus, int. carotid artery, C.

N. III, IV, VI, V

Sphenoid Sinus

Sphenoid Sinus

Sphenoid OstiumSphenoethmoidal RecessSphenoid Rostrum

Blood Supply : Infraorbital & supr dental art- Int max artery Br of antr & postr ethmoidal artery Pharyngeal br of Int max artery

Lymphatic drainage Lateral retropharyngeal & JD nodes

Physiology of PNSPhysiology of PNS Ventilation is paradoxical- air empties during

inspiration & is filled with air during expiration

Mucosa - ciliated columnar epithelium Goblet Cells

Glycoproteins—viscosity and elasticity Innervation (para=thick, symp=thin)

Basement membrane Sub mucosal glands.

Microscopic Anatomy

Mucous BlanketMucous Blanket

Two layers Superficial layer Sol layer

Function Superficial layer traps bacteria and

particulate matter. Enzymes, antibodies, immune cells

Mucociliary TransportMucociliary Transport

Directional Flow of Mucous Toward the choanae

Ostium drainage Contact inhibition

Haller’s cells Surgery

Mucociliary Transport

Function of Paranasal SinusesFunction of Paranasal Sinuses

Humidifying and warming inspired air Regulation of intranasal pressure Increasing surface area for olfaction Lightening the skull Resonance Absorbing shock Contribute to facial growth

Thank you..