anatomy of nose and paranasal sinuses

ANATOMY OF NOSE AND PARANASAL SINUSES

DR. DEEPIKA GARG

EXTERNAL NOSE

It is pyramidal in shape with its roof up and base directed downwards.

Nasal pyramid consists of osteocartilagenous framework covered with muscles and skin.

It consists of : Bony part Cartilagenous part

The bones of the nasal septum and other landmarks are: 1.nasal 2.frontal 3.ethmoid 4.sphenoid 5.vomer 6.perpendicular plate of ethmoid 7.maxilla 8.horizontal process of palatine bone 9.medial pterygoid plate 10.occipital condyle

CARTILAGES OF EXTERNAL NOSE AND COLUMELLA

Upper lateral cartilage: From under surface of nasal bonesabove,to the alar cartilage.

The lower free edge is seen intranasally as limen vestibulior nasal valve.

Lower lateral cartilage(greater alar cartilage):

U-shaped, has a lateral crus that forms the ala and a medial crus thatruns in the Columella.

Lesser alar or sesamoid cartilage: two or more They lie above and lateral to alar cartilage.

Septal cartilage: runs from under the nasal bones to the nasal tip, Supports the dorsum or cartilaginous part of nose

MUSCLES OF THE EXTERNAL NOSE

NASAL SKIN

Over nasal bones and upper lat.cartilages- thin, free, mobile

Over alar cartilages- thick, adherent with sebaceous glands

Hypertrophy of sebaceous glands: lobulated tumor Rhinophyma

BLOOD SUPPLY

Branches of facial artery supply the alar region.

Dorsal branch of ophthalmic artery supplies the dorsum of external nose.

Infraorbital branch of the maxillary artery supplies the lateral wall of external nose.

The fronto median area drains to the facial vein

The orbital palpebral area drains into the ophthalmic vein.

These have interconnection to the anterior ethmodial system and thence cavernous sinus.

NERVE SUPPLY

Skin of the external nose receives its sensory supply from the two upper division of trigeminal nerve: ophthalmic and maxillary .

The ophthalmic branch has--1. Infra trochlear branch which supplies

lateral surface of root of nose.2. External nasal branch which supplies skin

over the root and dorsum as far as tip of nose.

The infra orbital branch of the maxillary nerve gives:

1. External and internal nasal branches: which supply the nasal alae and skin of the nasal vestibule respectively.

2. Inferior palpebral and superior labial branches:which form pes anserinus minor with the superior buccal branches of facial nerve.

3. Anterior superior alveolar branch:which supplies anterior lateral wall.

INTERNAL NOSE

It is divided into right and left nasal cavity by nasal septum.

Each cavity comm.with exterior through the naris or nostril and with the nasopharynx through posterior nasal aperture or the choana.

Each cavity consists of a skin lined portion i.e.Vestibule, and a mucosa lined portion i.e. Nasal cavity proper

VESTIBULE

Anteroinferior part of nasal cavity is called Vestibule.

It is a dilated passage leading from the external nares into nasal fossa demarcated by limen nasi.

It is lined by skin bearing coarse hairs (vibrissae), sebaceous glands and sweat glands.

Its medial wall is formed by columella and lower part of septum upto its mucocutaneous junction.

NASAL CAVITY

Extends from external nares to posterior choanae and is narrow anteriorly than posteriorly.

Vertically it extends from palate to the cribriform plate.

It is divided into two by a septum. Each half has a floor, roof, lateral

and medial wall.

FLOOR OF NOSE

The floor is concave from side to side, flat anteroposteriorly and almost horizontal.

Anterior 3/4th composed of palatine process of the maxilla and posterior 1/4th by horizontal process of the palatine bone.

ROOF OF NOSE The roof is narrow from

side to side and divided into fronto-nasal , ethmoidal and sphenoidal parts.

The highest part of the nasal cavity which is related to the cribriform plate of ethmoid, is covered by the olfactory epithelium, while the rest of the nasal cavity is lined by respiratory mucus membrane and is continuous with that of paranasal sinuses, nasolacrimal duct and naso pharynx.

NASAL SEPTUM

BONES AND CARTILAGES Nasal septum is composed

of small anterior membranous portion, cartilage and several bones.

The perpendicular plate of the ethmoid, the vomer and the two bony crests of the maxilla and the palatine.

The cartilaginous portion composed of quadrilateral cartilage with contribution from lower and upper lateral alar cartilages forming the anterior septal angle.

Quadrilateral cartilage is bound firmly by collageneous fibres to the nasal bones and to the perpendicular plate of ethmoid and vomer.

Inferiorly it sits in the nasal crest of palatine process of the maxilla.

Anteriorly it is attached by a thin memebranous septum to the medial crura of lower lateral cartilages.

The upper margin of the cartilage expands where it is connected to upper lateral cartilage, forming the anterior septal angle.

Perpendicular plate forms the superior and anterior bony septum, is continuous above with the cribriform plate and crista galli.

The Vomer forms the posterior and inferior nasal septum and articulates with the rostrum of sphenoid.

The inferior border of vomer articulates with the nasal crest formed by the maxilla and the palatine bones.

The anterior border articulates with the perpendicular plate above and quadrilateral cartilage inferiorly.

The posterior edge of the vomer forms the free edge of the septum.

The nasal septum is of crucial importance in the development of middle 1/3rd of face.

EPITHELIUM OF INTERNAL NOSE

Vestibule: skin with hair,hair follicles and sebaceous glands

Olfactory region: (upper 1/3 of lateral nasal wall & nasal septum and roof) pale mucous membrane

Respiratory region: (lower 2/3 nasal cavity) variable thickness

meatus floor<conchae<septum pseudostratified ciliated columnar

epithelium

BLOOD SUPPLY

External and internal carotid arteries are responsible for the rich blood supply to the nose.

The sphenopalatine artery (branch of maxillary artery) supplies the posteroinferior septum.

The greater palatine artery (branch of maxillary artery) supplies the anteroinferior portion.

The superior labial branch of the facial artery contributes anteriorly to the kiesselbach’s plexus which is composed of unusually long capillary loops and is situated in little’s area on the anterior septum.

The internal carotid artery supplies the septum superiorly via the anterior and posterior ethmoidal arteries and also contributes to the kiesselbach’s plexus.

NERVE SUPPLY

The maxillary division of the trigeminal nerve provides sensory supply to the majority of the nasal septum.

The naso palatine nerve supplies bulk of the bony septum and in the nasal cavity via the sphenopalatine foramen passing medially across the roof to the upper septum and running down and forwards to the incisive canal to reach the hard palate.

The anterosuperior part of the septum is supplied by anterior ethmoidal branch of nasociliary nerve and a smaller anteroinferior portion receives branch from anterior superior alveolar nerve.

The posteroinferior septum also receives a small supply from the nerve to the pterygoid canal and a posterior inferior nasal branch of the anterior palatine nerve.

LATERAL NASAL WALL

It is marked by three scroll-like bony projections called TURBINATE or CONCHAE.

From below upwards they are: inferior middle superior Sometimes a fourth turbinate may

be present i.e. CONCHA SUPREMA.

INFERIOR TURBINATE

This structure is composed of a separate bone, the inferior concha which has irregular surface.

The bone has maxillary process which articulates with the inferior margin of the maxillary hiatus.

It also articulates with the ethmoid, palatine and lacrimal bones completing medial wall of the nasolacrimal duct.

The turbinate possesses submucosal cavernous plexus with large sinusoids under autonomic control which provides major contribution to nasal resistance.

The turbinate is covered by respiratory epithelium, with a high number of goblet cells which decrease in the density towards the posterior end.

INFERIOR MEATUS It is that part of lateral wall

which is lateral to the inferior turbinate.

It is the largest and highest at the junction of anterior and middle one third.

In adults it ranges from 1.6-2.3cm at 1.6cm along the bony lateral wall.

The nasolacrimal duct opens just anterior to the highest point.

It has no true valve and can be identified by applying gentle pressure into lacrimal sac at the medial canthus.

MIDDLE TURBINATE:

Most ant. the turbinate attaches to maxilla, just ant. to which is the bulge of agger nasi.

The ant.1/3 attaches vertically to skull base at the lateral border of the cribriform niche with the frontal bone forming the roof of the ethmoid.

The post.1/3 attaches horiz. to the lamina papyracea and medial wall of the maxilla.

MIDDLE MEATUS

It is that portion of the lateral nasal wall which lies lateral to middle turbinate.

It receives drainage from: frontal,

maxillary and ant.ethmoidal sinuses.

SUPERIOR MEATUS: The posterior ethmoidal

cells open into this region.

SPHENO ETHMOIDAL RECESS:

lies medial to the superior turbinate. It is the location of the

ostium of the sphenoid sinus.

BLOOD SUPPLY OF THE LATERAL WALL

The sphenopalatine artery (from the maxillary artery and thus external carotid artery) contributes to the majority of the blood supply to the turbinates and the meatus.

It enters through the sphenopalatine foramen which lies thus inferior to the horizontal attachment of the middle meatus and may be damaged in excessive enlargement of middle meatal antrostomy.

In the inferior meatus the sphenopalatine branch supplies the anterior portion leaving the central portion relatively avascular.

Anteriorly an area is supplied by a branch from facial.

Part of lateral wall adjacent to the palate receives blood from greater palatine artery.

Via the ethmoidal arteries, internal carotid arteries supplies the superior lateral wall.

Vascular supply to the nose is enhanced by the cavernous plexus found in the lamina propria in particular in the inferior and middle turbinates.

Veins of the plexus are between 0.1 and 0.5mm wide and anastomose with each other.

Venous drainage to the # sphenoplatine vein via facial and

ophthalmic vessels # intracranially via the ethmoidal

veins to the veins on dura and # to the superior sagittal sinus

NERVE SUPPLY OF THE LATERAL WALL Lateral wall receive sensory supply # from anterior ethmoidal nerve

anterosuperiorly. # from branches of pterygopalatine

ganglion and anterior palatine nerves posteriorly.

# anteriorly small area is innervated by infra orbital nerve.

Anterosuperior alveolar nerve sends a small branch to anteroinferior meatus which may be damaged in inferior meatal surgery affecting the dental sensation.

LYMPHATIC DRAINAGE

Lateral wall drains with the external nose to :

# submandibular nodes anteriorly.

# lateral pharyngeal, retropharyngeal and upper deep cervical nodes posteriorly.

APLLIED ANATOMY

DANGEROUS AREA OF FACE EPISTAXIS: LITTLE’S AREA: ant.epistaxis sphenopalatine artery retrocolumellar vein WOODRUFF’S AREA: post.epistaxis posterior end of inf.turbinate sphenopalatine anastomoses with

posterior pharyngeal artery

THE ETHMOIDALBONE AND SINUS

OSTEOLOGY

Ethmoid bone composed of five parts:-

Two ethmoid labyrinths suspended either side of perpendicular plate which forms upper portion of bony nasal septum, with an intervening cribriform plate and a superior midline extension, crista galli.

Perpendicular plate: quadrilateral in shape and articulates with the nasal spine of frontal and nasal bones, posteriorly with sphenoid and vomer.

Crista galli: ranges from 15.1 to 31.4mm and may be pneumatised and/or contain marrow.

Cribriform plate: divides the nasal cavity from the anterior cranial fossa.

-through the fenestration the olfactory filaments, ethm. vs. and nerves and dural prolongations traverse.

BASAL LAMELLA

Between the two portions of middle turbinate, there is an obliquely disposed plate of bone, the basal lamella of the middle turbinate.

It attaches laterally to the lamina papyracea.

It divides the ethmoidal labyrinth into anterior and posterior group of cells.

ETHMOIDAL LABYRINTH

It is a collection of cells and clefts. The lateral walls constitute the orbital

plates or lamina papyracea. The lamina is extremely thin. The anterior cells are generally smaller

and more numerous than the posterior group.

The largest and most constant anterior cells form the bulla ethmoidalis opening directly into the middle meatus.

Posterior cells drain into superior meatus. These cells are large and pyramidal in

shape, pointing towards the orbital apex. The most posterior ethmoidal cells can

extend lateral to sphenoid, this configuration was originally described by “ONODI” hence bears his name.

The optic nerve is particularly vulnerable in such cells.

The ethmoidal cells may pneumatise the orbital floor, forming the Haller cells.

Pneumatisation proceeds from anterior cells in 70% and from posterior cells in 30%.

ETHMOIDAL ARTERIES AND VEINS

Ethmoidal arteries arise from ophthalmic artery, a branch of internal carotid.

The anterior artery accompanies the nerve and supplies anterior ethmoidal cells and frontal sinus.

It passes through anterior ethmoidal canal in the medial wall of orbit, traverses roof of ethmoid, passes through the vertical attachment of middle turbinate, abuts the base of skull and reaches the superior surface of cribriform plate where it gives off MENINGEAL branch.

The artery then passes down to supply the upper nasal septum and lateral wall of nose, sending a terminal branch to nasal dorsum, between the nasal bone and upper lateral cartilages.

the anterior ethmoidal artery is unilaterally absent in 14%, bilaterally absent in 2% and multiple in 30%.

When absent it is replaced by posterior ethmoidal artery which runs through the canal in the medial wall to supply the posterior ethmoidal cells and also gives MENINGEAL branch and terminates in NASAL branches to septum and lateral wall, anastomosing with sphenopalatine artery.

THE SPHENOID BONE AND SINUSES

OSTEOLOGY

Sphenoid bone is largest in skull base and divides anterior and middle cranial fossa.

Composed of a body, two wings (greater and lesser) and two inferior plates (lateral and medial pterygoid plates).

The anterior surface articulates with the cribriform plate. This surface bears the chiasmatic sulcus connecting the optic canals, the tuberculum sellae, sella turcica and dorsum sellae with related anterior, middle and clinoid process.

The lateral surface on the body is grooved by carotid sulcus on each side as it traverses the cavernous sinus.

The anterior face of the body bears a crest which articulates with the perpendicular plate of the ethmoid.

On either side, halfway up the face lie the ostia of sinuses. They are large(5-8mm in diameter) on a macerated skull, but are partially overlapped and closed by sphenoidal concha and by mucus membrane in life.

The sinuses open into the sphenoethmoidal recess, superior and median to the superior turbinate.

The sinus cavities are variable in size and shape. Pneumatization can extend into the greater wing.

Four general forms of pneumatization are described:---

1. Conchal pneumatization, with only a rudimentary sinus(2-3%).

2. Presellar, in which the sinus is pneumatized as far as the anterior bony wall of the pituitary fossa(11%).

3. Sellar, in which pneumatization extends back beneath the pituitary fossa(59%).

4. Mixed(27%).

The sinuses are divided by a septum which is often paramedian and there may be diverticula and incomplete septa. It is completely absent in approximately 1% of population.

The inferior surface of the body bears the rostrum which articulates with the vomer.

The greater wings contribute to the middle cranial fossa and lateral wall of the orbit.

The bone is traversed by a no. of foramina:--------

1. Foramen rotundum: transmits the maxillary nerve.

2. Foramen ovale: transmits the mandibular nerve, accessory meningeal artery ,lesser petrosal nerve and emissary vein (MALE)

3. Foramen spinosum: transmits middle meningeal artery and meningeal branch of mandibular nerve.

4. Foramen lacerum: br.of ICA

Each pterygoid process consists of a lateral and medial plate.

The process is pierced superiorly by pterygoid canal which transmits the pterygoid nerve and artery.

The lateral pterygoid muscle arises in part from the lateral surface of the lateral pterygoid plate and the medial pterygoid muscle arises from its medial surface.

The medial pterygoid plate ends in a hamulus, around which the tendon of tensor veli palatini hooks.

RELATIONS:

Anterior: posterior ethmoidal cells and sphenoethmoidal recess.

Posterior: occipital bone, basilar artery and brain stem.

Lateral: cavernous sinus, internal carotid arteries, sympathetic plexus, vi, iii, iv, ophthalmic and maxillary divisions of v cranial nerves.

Inferior: roof of nasopharynx Superior: olfactory tracts, frontal lobes ,

optic chiasma and pituitary gland.

NERVES AND BLOOD SUPPLY

The sphenoid sinuses are supplied by posterior ethmoidal vessels and nerves with additional supply from orbital branches of pterygopalatine ganglion.

Lypmhatics drain into retropharyngeal nodes.

FRONTAL BONE AND SINUS

OSTEOLOGY

Frontal bone forms the forehead and orbital roof.

It forms the roof of ethmoidal sinus which produce impressions upon it called fovea ethmoidales ossis frontalis.

Shape and size vary from person to person and in approximately 1% of population they are absent.

When present it is “L” shaped and composed of a horizontal and vertical compartment.

An intersinus septum is usually present which may be Para median or partially dehiscent (9%).

The sinus drains into frontal recess by an hour glass narrowing.

Accessory channels are found in 12%. Direct continuity of drainage between the

frontal and maxillary sinus may be found depending on the attachment of uncinate process.

RELATIONS:

Inferior: orbit, ethmoid labyrinth and nasal cavity.

Superior: anterior cranial fossa, olfactory niche, bulbs and tract.

Medial: cribriform plate and olfactory niche.

BLOOD AND NERVE SUPPLY:

Supraorbital and anterior ethmoidal artery supplies the frontal sinuses.

Venous drainage includes accompanying veins, diploic veins and an anastomotic vein in the supraorbital notch connecting supraorbital and superior ophthalmic vessels.

The nerve supply derived from supraorbital nerve.

Lymphatics: submandibular gland.

THE MAXILLARY BONE AND SINUS

OSTEOLOGY:

It is the second largest facial bone. Forms majority of roof of mouth, lateral

wall, floor of nasal cavity and orbit. Body is usually described as quadrilateral

pyramid and contains maxillary sinus. The bone has four processes: zygomatic, frontal, palatine and alveolar.

It articulates with 8 bones: the opposite maxilla, zygoma, frontal, palatine, ethmoid, lacrimal, inferior concha and nasal bones.

Anterior surface bears no. of elevation and depressions related to dentition.

Roof of maxillary sinus forms most of orbital floor and is traversed by infraorbital canal.

Anteromedially it has lacrimal notch which is related to lacrimal sac.

Posterior edge contributes to inferior orbital fissure.

The posterior, infratemporal surface of the bone is convex and grooved by posterosuperior alveolar nerve.

The medial nasal surface forms floor of pyramid and contains a large defect, the maxillary hiatus.

Lacrimal canal is created between maxilla, lacrimal bone and inferior concha through which nasolacrimal duct passes to anterior part of inferiormeatus.

When the two maxilla are articulated, alveolar processes form the alveolar arch.

The frontal process bears the anterior lacrimal crest, the palatine process forms large portion of the floor of nose and roof of mouth.

Posteriorly palatine process articulates with horizontal plate of the palatine bone to complete the hard palate.

RELATIONS:

Superior: infraorbital artery and nerve, orbit.

Inferior: upper dentition and hard palate.

Posterior: pterygopalatine and infratemporal fossa.

Anteriorly: skin, fat and facial musculature.

BLOOD AND NERVE SUPPLY: Small branches of facial, maxillary ,

infraorbital and greater palatine arteries and veins supply the maxilla.

Venous drainage is to the anterior facial vein and pterygoid plexus.

The maxillary division of the trigeminal nerve supplies sensation via infraorbital, superior alveolar and greater palatine nerves.

Posterior alveolar nerve supplies the adjacent mucosa and molar teeth.

Middle superior alveolar nerve supplies lateral wall of sinus and upper premolar teeth.

Greater palatine nerve supplies the posteromedial wall of sinus while the infraorbital nerve supplies the roof.

Lymphatic drainage is into pterygopalatine fossa and then to submandibular lymph nodes.