nose and paranasal sinus

Nose and ParanasalSinus

Dr. Deepak K Gupta

www.facebook.com/notesdental

NASAL CAVITIES

• Uppermost parts of the respiratory tract and contain the olfactory receptors

• Elongated wedge-shaped spaces with a large inferior base and a narrow superior apex

• Skeletal framework consisting mainly of bone and cartilage– Nares – external opening of

nose– Choanae - open into the

nasopharynx


Skeletal framework

• Bones that contribute to the skeletal framework of the nasal cavities include

– Unpaired: ethmoid, sphenoid, frontal bone, and vomer;

– Paired: nasal, maxillary, palatine and lacrimal bones, and inferior conchae


Ethmoid bone

• Most complex bones in the skull• Contributes to the roof, lateral wall, and medial wall

of both nasal cavities, and contains the ethmoidal cells (ethmoidal sinuses)

• Cuboidal in overall shape • Two rectangular box-shaped ethmoidal labyrinths one

on each side• These are united superiorly across the midline by a

perforated sheet of bone (cribriform plate). • A second sheet of bone (perpendicular plate) descends

vertically in the median sagittal plane to form part of the nasal septum


Ethmoid bone


External nose

• Pyramidal in shape with its apex anterior in position

• Composed partly of bone and mainly of cartilage– Bony parts - continuous with the skull bones and

parts of the maxillae and frontal bones

– Cartilaginous Part - anteriorly, and on each side• Laterally - lateral processes of the septal cartilage,

major alar and three or four minor alar cartilages

• Single septal cartilage in the midline that forms the anterior part of the nasal septum


Nasal Cartilage


NASAL CAVITIES


NASAL CAVITIES • The nasal cavities are

separated - each other by a midline nasal septum

• Oral cavity below by the hard palate

• Cranial cavity above by parts of the frontal, ethmoid, and sphenoid bones

• Each nasal cavity has a floor, roof, medial wall, and lateral wall www.facebook.com/notesdental

Lateral wall

• Characterized by three curved shelves of bone (conchae)

• One above the other and project medially and inferiorly across the nasal cavity

• The medial, anterior, and posterior margins of the conchae are free

• Increase the surface area of contact between tissues of the lateral wall and the respired air

• Openings of the paranasal sinuses, which are extensions of the nasal cavity

• Opening of the nasolacrimal ductwww.facebook.com/notesdental

Lateral wallConchae divide each nasal cavity into four air channels

•Inferior nasal meatus between the inferior concha and the nasal floor•Middle nasal meatus between the inferior and middle concha; •Superior nasal meatus between the middle and superior concha; •Spheno-ethmoidal recess between the superior concha and the nasal roof


Lateral wall


Medial Wall• Mucosa-covered surface of the thin nasal

septum

• Oriented vertically in the median sagittal plane

• Separates the right and left nasal cavities from each other

• It consists of– Anteriorly: Septal nasal cartilage

– Posteriorly: mainly the vomer and the perpendicular plate of the ethmoid bone;

• Nasal spine of the frontal bone - meet in the midline


Medial Wall


Floor

• Smooth, concave, and much wider than the roof

• It consists of

– Soft tissues of the external nose;

– Upper surface of the palatine process of the maxilla,

– Horizontal plate of the palatine bone, which together form the hard palate

• Naris opens anteriorly into the floor,

• Superior aperture of the incisive canal - deep to the mucosa

– immediately lateral to the nasal septumwww.facebook.com/notesdental

Floor


Roof

• Narrow and is highest in central regions where it is formed by the cribriform plate of the ethmoid bone

• Anterior to the cribriform plate - roof slopes inferiorly to the nares and consist– nasal spine of the frontal bone and the nasal bones

– lateral processes of the septal cartilage and major alarcartilages

• Posteriorly, the roof slopes inferiorly to the choana and is formed by– Anterior surface of the sphenoid bone;

– Ala of the vomer

– Medial plate of the pterygoid process. www.facebook.com/notesdental

Roof


Regions of Nasal Cavities• Each nasal cavity consists of three general regions• Nasal vestibule

– small dilated space just internal to the naris that is lined by skin and contains hair follicles

• Respiratory region– Largest part of the nasal cavity– Rich neurovascular supply– Lined by respiratory epithelium composed mainly of

ciliated and mucous cells

• Olfactory region – small, is at the apex of each nasal cavity– Lined by olfactory epithelium which contains the

olfactory receptorswww.facebook.com/notesdental

Regions of Nasal

Cavities


Functions of Nasal Cavities

• Main: housing receptors for the sense of smell (olfaction)

• Accessory– Adjust the temperature and humidity of respired air -

action of a rich blood supply,

– Trap and remove particulate matter - hair in the vestibule

– Capturing foreign material in abundant mucus.

– Mucus normally is moved posteriorly by cilia on epithelial cells in the nasal cavities and is swallowed


Nerve Supply of Nose• Three cranial nerves

– Olfaction - the olfactory nerve [I]

– General sensation - the trigeminal nerve [V], • Anterior - ophthalmic nerve [V1]

• Posterior - maxillary nerve [V2]

– Glands - parasympathetic fibers in the facial nerve [VII] (greater petrosal nerve), • Join branches of the maxillary nerve [V2] in the

pterygopalatine fossa.

• Sympathetic fibers are ultimately derived from the T1 spinal cord level


Nerve Supply


Blood supply

• Blood supply to the nasal cavities is by

– Terminal branches of the maxillary and facial arteries - originate from the external carotid artery (ECA)

– Ethmoidal branches of the ophthalmic artery, which originates from the internal carotid artery.


Blood Supply


Blood Supply : Nasal Spetum• The anterior part of the septum contains a highly

vascularized area called Kiesselbach’s area• Supplied by vessels from both major arteries. • This area is the most common site of significant

nose-bleed due to anastomoses.


Lymphatics• Anterior regions

– drains forward onto the face by passing around the margins of the nares -submandibular nodes

• Posterior regions of the nasal cavity and the paranasal sinuses• drains into upper deep

cervical nodes through the retropharyngeal nodes


PARANASAL SINUS


PARANASAL SINUS• Invaginations from the

nasal cavity that drain into spaces associated with the lateral nasal wall

• There are four paranasal air sinuses– Ethmoidal cells, – Sphenoidal,– Maxillary, – Frontal sinuses

• Functions: skull lighter and add resonance to the voice

• Infection causes Sinusitis


PARANASAL SINUS


PARANASAL SINUS

• Rudimentary or even absent during birth

• Enlarges rapidly at the age of 6 to 7 yrs then after puberty

• Increase in size due to– Enlargement of Bones :

birth till adult life– Resorption of Bones:

old age

• Lined by a respiratory epithelium


PARANASAL SINUS


Frontal sinuses

• One on each side• Variable in size and are the most superior of the

sinuses – average size 2.5 cm• Each is triangular in shape• Rudimentary at birth and usually well-developed by

the age of 7 or 8 years• Part of the frontal bone under the forehead• Drains onto the lateral wall of the middle meatus via

the frontonasal duct– which penetrates the ethmoidal labyrinth and continues

as the ethmoidal infundibulum at the front end of the semilunar hiatus


Frontal sinuses


Frontal sinuses

• Relations of Sinus

– Superior: anterior cranial fossa and contents

– Inferior: orbit, anterior ethmoidal sinuses, nasal cavity

– Anterior: forehead, superciliary arches

– Posterior: anterior cranial fossa and contents

– Medial: other frontal sinus

• Location of Ostium : Middle meatus


Frontal sinuses

• Branches of the supra-orbital nerve and Supra-trochlear nerve from the ophthalmic nerve [V1]

• Blood supply is from branches of the anterior ethmoidalarteries, supraorbitaland supra-trochlearartery


Ethmoidal Sinus

• Composed of three sets of ethmoidal air cells– Anterior– Middle– Posterior

• 3 to 18 ethmoid air cells on each side• Thin-walled, bony, honeycombed spaces collectively

form the ethmoidal labyrinth located between the orbits and the nasal fossae

• May invade any of the other 3 sinuses• Ethmoid bulla: middle ethmoid air cells produce the

swelling on the lateral wall of the middle meatus


Ethmoid Sinus• Relations of Sinus

– Superior: anterior cranial fossa and contents, frontal bone with sinus

– Medial: nasal cavity– Lateral: orbit

• Location of Ostium– Anterior: middle meatus

(frontonasal duct or ethmoidal infundibulum)

– Middle: middle meatus(on or above ethmoidbulla)

– Posterior: superior meatus


Ethmoid Sinus

• Innervated by: – the anterior and posterior ethmoidal branches of the

nasociliary nerve from the ophthalmic nerve [V1]– the maxillary nerve [V2] via orbital branches from the

pterygopalatine ganglion.

• It receive their blood supply through branches of the anterior and posterior ethmoidal arteries

• Primary lymphatic drainage– Submandibular lymph nodes - anterior and middle

ethmoid sinuses– Retropharyngeal lymph nodes - posterior ethmoid

sinus


Ethmoid Sinus : Blood Supply


Opening of Paranasal Sinus


Ethmoid Sinus : Nerve Supply


Maxillary sinuses

• One on each side, are the largest of the paranasalsinuses – 3.5 X 2.5 X 3.5 cms

• Completely fill the bodies of the maxillae

• Pyramidal in shape– Roof : inferior orbital margin

– Floor : Alveolus of the maxilla

– Base: lateral wall of nose

– Apex : zygomatic process of maxilla


Maxillary sinuses

• Relations of Sinus– Superior: orbit, infraorbital nerve and vessels

– Inferior: roots of molars and premolars

– Medial: nasal cavity

– Lateral and anterior: cheek

– Posterior: infratemporal fossa, pterygopalatine fossa and contents

• Location of Ostium : near the top of the base, in the center of the semilunar hiatus, which grooves the lateral wall of the middle nasal meatus– 2nd opening may be present at the posterior end of hiatus


Maxillary sinuses

• Size of opening is large in isolated maxilla, but it gets reduced in intact skull – 3-4 mm

– Unicate process of ethmoid and descending part of lacrimal bine

– Below - Inferior nasal conchae

– Behind – perpendicular plate of palatine bone

– Further reduced by thick mucosa of nose


Maxillary sinuses


Maxillary sinuses

• Innervated by infra-orbital and alveolar branches of the maxillary nerve [V2],

• Receive their blood through branches from the infra-orbital and superior alveolar branches of the maxillary arteries

• Primary lymphatic drainage is to the submandibular lymph nodes


Maxillary sinuses: Blood Supply


Maxillary sinuses : Nerve Supply


Sphenoidal sinuses

• Two large, irregularly shaped cavities• Separated by an irregular septum• Relations of Sinus

– Superior: hypophyseal fossa, pituitary gland, optic chiasma

– Inferior: nasopharynx, pterygoid canal– Medial: other sphenoid bone– Lateral: cavernous sinus, internal carotid artery,

cranial nerves III, IV, V1, V2, and VI– Anterior: nasal cavity

• Location of Ostium : Sphenoethmoidal recess


Sphenoidal sinuses


Innervation

• Innervation of the sphenoidal sinuses is provided by

– the posterior ethmoidal branch of the ophthalmic nerve [V1]; and

– the maxillary nerve [V2] via orbital branches from the pterygopalatine ganglion.

• Supplied by branches of the pharyngeal arteries from the maxillary arteries


Sphenoidal sinuses: Blood Supply


Sphenoidal sinuses: Nerve Supply


Opening of Paranasal Sinus


Clinical Correlate : SINUSITIS

• An inflammation of the membrane of the sinus cavities caused by infections (by bacteria or viruses) or noninfectious means (such as allergy)

• 2 types of sinusitis: acute and chronic

• Common clinical manifestations– sinus congestion

– Discharge

– Pressure

– face pain

– headaches


Acute Sinusitis

• The most common form of sinusitis

• Typically caused by a cold that results in inflammation of the sinus membranes

• Normally resolves in 1 to 2 weeks

• Sometimes a secondary bacterial infection may settle in the passageways after a cold;– bacteria normally located in the area -

Streptococcus pneumoniae and Haemophilusinfluenzae)


Chronic Sinusitis• An infection of the sinuses that is present for

longer than 1 month and requires longer duration medical therapy

• Typically either chronic bacterial sinusitis or chronic noninfectious sinusitis

• Chronic bacterial sinusitis is treated with antibiotics

• Chronic noninfectious sinusitis often is treated with steroids (topical or oral) and nasal washes


Chronic Sinusitis

• Locations– Maxillary: the most common location for sinusitis;

associated with all of the common signs and symptoms but also results in tooth pain, usually in the molar region

– Sphenoid: rare, but in this location can result in problems with the pituitary gland, cavernous sinus syndrome, and meningitis

– Frontal: usually associated with pain over the forehead and possibly fever; rare complications include osteomyelitis

– Ethmoid: potential complications include meningitis and orbital cellulitis


References

• Grays Anatomy for Students 2nd Edition

• Head and Neck Anatomy for Dental Medicine

• Head, Neck and Dental Anatomy, 4th Edition

• Netter’s Head and Neck Anatomy for Dentistry, 2nd Edition Neil S norton

• Oral Development and Histology, 3rd Edition

• Woelfel's Dental Anatomy

• Ten Cate’s Oral Histology - Development, Structure, and Function, 7th Edition


nose and paranasal sinus

Health & Medicine

nasal cavity

nasal cartilage

nasal roof

nasal cavities uppermost

lateral wall conchae

ethmoid bone

inferior conchae

skull bones