& INTRODUCTION TO NOSE AND ITS SKELETON

05/07/2021 2 External nose • Extends the nasal cavities onto the front of the face & point inferiorly.

• Pyramidal in shape with its apex anterior in position.

05/07/2021 3 External nose

• The bony parts are where the nose is continuous with the skull-here the nasal bones and parts of the maxillae and frontal bones provide support;

• Anteriorly, support is provided by lateral processes of the septal cartilage, major alar and 3 or 4 minor alar cartilages, and a single septal cartilage in the midline that forms the anterior part of the .

05/07/2021 4 NASAL SEPTUM

05/07/2021 5 INTRODUCTION TO NASAL CAVITY • The two nasal cavities are the uppermost parts of the respiratory tract. • They are elongated wedge- shaped spaces with a large inf. base & a narrow sup. apex and are held open by a skeletal framework (bone & cartilage). • Apertures (Ant. & Post.) • Mucosa linning

Seprated from: • Oral cavity by the hard palate; • Cranial cavity by parts of the frontal, ethmoid & sphenoid. 05/07/2021 6 • Lat. to them are the orbits. Regions • Nasal vestibule, small dilated space internal to naris, lined by skin & contains hair follicles;

• Respiratory region, largest part of the nasal cavity, has a rich neurovascular supply, lined by ciliated epithelium and mucous cells;

• Olfactory region, at the apex of each nasal cavity, contains the olfactory receptors.

05/07/2021 7 • Mucosa lines the nasal cavity, except for the nasal vestibule, which is lined with skin. • Mucosa is firmly bound to the periosteum and perichondrium of the supporting bones and cartilages. Mucosa is continuous with the lining of all the chambers with which the nasal cavities communicate: • Nasopharynx posteriorly, • Paranasal sinuses superiorly and laterally, and • Lacrimal sac and conjunctiva superiorly. • The inferior 2/3 of NC is the respiratory area and the superior 1/3 is the olfactory area.

05/07/2021 8 Skeletal framework

• Unpaired ethmoid, sphenoid, frontal bone & vomer; • Paired nasal, maxillary, palatine, lacrimal bones & inferior conchae.

05/07/2021 9 Skeletal frame work Perpendicular plate articulate: • Postly, sphenoidal crest on the body of sphenoid bone; • Antly, nasal spine on the frontal bone and the two nasal bones; • infely, septal cartilage (ant) & vomer (post).

05/07/2021 10 ROOF • The roof of the nasal cavity is curved and narrow, except at its posterior end; it is divided into three parts (frontonasal, ethmoidal, and sphenoidal) Ant. to cribriform plate, the roof is formed by: • Nasal spine of frontal bone& nasal bones; • Lateral processes of the septal cartilage & major alar cartilages of the external nose. Posteriorly, the roof slopes inferiorly to the and is formed by: • Anterior surface of the sphenoid bone; • Ala of the vomer and sphenoidal process of the palatine bone; • Vaginal process of the medial pterygoid plate.

The opening between sphenoidal sinus & spheno-ethmoidal recess is on the post 05/07/2021 slope of the roof. 11 FLOOR

• The floor is smooth, concave, and much wider than the roof. It consists of: soft tissues of the external nose; • Formed by the upper surface of the palatine process of the maxilla & the horizontal plate of the palatine bone, which together form the hard palate.

05/07/2021 12 Medial wall The MW of each NC is the mucosa-covered surface of the thin nasal septum. Nasal septum consists of • anteriorly; • Posteriorly-vomer & the perpendicular plate of EB; • small contributions by the nasal bones and the nasal spine of frontal bone; • Nasal crests of the maxillary and palatine bones, rostrum of the sphenoid bones, and the 05/07/2021 incisor crest of the maxilla 13 LATERAL WALL • LW is complex, formed by bone, cartilage & soft tissues. Bony support is provided by: • Ethmoidal labyrinth & uncinate process; • Perpendicular plate of the palatine bone; • Medial pterygoid plate of the sphenoid bone; • Medial surfaces of the lacrimal bones and maxillae; • Inferior concha. 05/07/2021 14 Lateral wall • In the external nose, LW is supported by cartilage (lateral process of the septal cartilage and major and minor alar cartilages) and by soft tissues.

• The surface of the lateral wall is irregular in contour and is interrupted by the three nasal conchae.

• Conchae extend medially across the nasal cavity, separating it into four air channels (IM,MM,SM & 05/07/2021 SER). 15 Lateral Wall • Characterized by 3 curved shelves of bone (conchae), which project infriomedially across the nasal cavity. • The med, ant& post margins of the conchae are free. • Meatus: • Inferior ; • Middle nasal meatus; • Superior nasal meatus; • Spheno-ethmoidal recess. • medially placed Common nasal05/07/2021 meatus 16 • Inf. to the attachment of the middle concha & ant to the Lateral wall & its openings midpoint of the concha, the lateral wall of the middle meatus elevates to form the dome-shaped ethmoidal bulla, EB (formed by underlying middle ethmoidal cells). • Inf. To EB is a curved gutter (the hiatus semilunaris), which is formed by the mucosa & spans a defect in the bony wall between EB & uncinate process below. • Ant. end of the hiatus semilunaris forms a channel (the ethmoidal infundibulum), which curves superoirly & continues as the frontonasal

duct05/07/2021 to open into the frontal 17 sinus. APERTURES • The nares are oval Nares apertures on the inferior aspect of the external nose and are the anterior openings of the nasal cavities.

• They are held open by the surrounding alar & septal cartilages, and by the inferior nasal spine and adjacent margins of the maxillae. 05/07/2021 18 Nares Although the nares are continuously open, they can be widened further by the action of the related muscles of facial expression: • Nasalis muscle, • Depressor septi nasi, • Levator labii superioris alaeque nasi.

05/07/2021 19 Choanae

Oval-shaped openings between the nasal cavities and the nasopharynx. Unlike the nares, the choanae are rigid openings completely surrounded by bones that form the margins:

• Inferiorly-post border of the horizontal plate of palatine bone; • Laterally-post margin of the medial plate of the pterygoid process; • Medially-post border of the vomer.

The roof of the choanae is formed: • Anteriorly-ala of the vomer and the vaginal process of the medial pterygoid plate; • Posteriorly-body of the sphenoid bone.

05/07/2021 20 Other Apertures • Cribriform foramina (fibers of the olfactory nerve, anterior ethmoidal nerve & accompanying vessels).

• Sphenopalatine foramen (sphenopalatine branch of the max artery, nasopalatine & superior nasal branches of the max nerve),

• Incisive canal (nasopalatine nerve-NC to OC, terminal end of the greater palatine artery-OC to NC),

• Small foramina (internal nasal branches of the infra-orbital nerve of V2, , alar branches of nasal artery from the facial artery, inferior nasal branches from the greater palatine branch of V2.

05/07/2021 21 Arteries

05/07/2021 22 VASCULATURE AND INNERVATION OF THE NOSE Arterial supply to the medial and lateral walls is from 5 sources: • Ant. ethmoidal artery (ophthalmic a.) • Post. ethmoidal artery (ophthalmic a.) • Sphenopalatine artery (maxillary a.) • Greater palatine artery (maxillary a.) • Septal branch of the superior labial artery (facial a.)

• The ant. part of the nasal septum is the site (Kiesselbach area) of an anastomotic arterial plexus involving all 5 arteries supplying the septum. • The external nose also receives blood from 1&5 arteries listed plus nasal branches of the infraorbital artery and the lateral nasal branches of the facial artery. 05/07/2021 23 Veins • A rich submucosal venous plexus deep to the nasal mucosa drains into the sphenopalatine, facial and ophthalmic veins.

• This venous plexus is an important part of the body's thermoregulatory system, exchanging heat and warming air before it enters the lungs.

05/07/2021 24 Nerve supply Nasal mucosa can be divided into: • Posteroinferior and anterosuperior portions (by an oblique line passing approximately through the apex of the nose & sphenoethmoidal recess. Nerve supply of the posteroinferior portion of nasal mucosa is chiefly from • Maxillary nerve, via nasopalatine nerve to the nasal septum, and Greater palatine nerve via Post, Sup ,Lat & Inf. lateral nasal branches to the lateral wall. Nerve supply of the anterosuperior portion is from

• Ophthalmic nerve (CN V1) via ant. & post ethmoidal nerves, branches of the nasociliary nerve. • Most of the external nose (dorsum and apex) is also supplied by CN V1 (via the infratrochlear nerve and the external nasal branch of the anterior ethmoidal nerve), • Alae are supplied by the nasal branches of the infraorbital nerve (CN V2).

 The olfactory nerves, concerned with smell 05/07/2021 25 Nerves

05/07/2021 26 Lymphatics • Lymph from anterior regions drains forward onto the face by passing around the margins of the nares ultimately connect with the submandibular nodes. • Lymph from posterior regions of the nasal cavity and the paranasal sinuses drains into upper deep cervical nodes. Some of this lymph passes first through the retropharyngeal nodes.

05/07/2021 27 CLINICAL CORRELATES Rhinitis The nasal mucosa becomes swollen and inflamed (rhinitis) during severe upper respiratory infections and allergic reactions (e.g., hayfever). Swelling of the mucosa occurs readily because of its vascularity. Infections of the nasal cavities may spread to the: • Anterior cranial fossa through the cribriform plate. • Nasopharynx and retropharyngeal soft tissues. • Middle ear through the pharyngotympanic tube (auditory tube), which connects the tympanic cavity and nasopharynx. • Paranasal sinuses. • Lacrimal apparatus and conjunctiva. 05/07/2021 28 • Epistaxis – Epistaxis (nosebleed) is relatively common because of the rich blood supply to the nasal mucosa. – In most cases, the cause is trauma and the bleeding is from an area in the anterior third of the nose (Kiesselbach area). – Epistaxis is also associated with infections and hypertension. Spurting of blood from the nose results from rupture of arteries. – Mild epistaxis may also result from nose picking, which tears veins in the vestibule of the nose. • Nasal Fractures • Deviation of the Nasal Septum

05/07/2021 29 PARANASAL SINUSES

Develop as outgrowths from the nasal cavities and erode into the surrounding bones.

• Lined by respiratory mucosa, which is ciliated and mucus secreting; • Open into the nasal cavities; • Innervated by branches of the trigeminal nerve.

05/07/2021 30 THE 4 PARANASAL SINUSES

05/07/2021 31 FRONTAL SINUSES • FS drains onto lateral wall of the middle meatus via . • Usually detectable in children by 7 years of age • Their average dimensions are: height 3.2 cm; breadth 2.6 cm; depth 1.8 cm. • FSes are innervated by branches of supra-orbital

from V1. & supply by branches

05/07/2021 of ant. ethmoidal arteries. 32

Ethmoidal cells • Ethmoidal cells fill the ethmoidal labyrinth. • Are small invaginations of the mucous membrane of the middle and superior nasal meatus into the ethmoid bone between the nasal cavity and the orbit • Range from 3 large to 18 small sinuses on each side ECs are formed by a variable number of individual air chambers, which are divided: • Ant. ECs (11) open into the ethmoidal infundibulum or the frontonasal duct; • Middle ECs (< 3) forms the ethmoidal bulla, opens directly into the middle meatus on the lateral wall • Post. Ecs (1 to 7) open onto the superior nasal meatus.

ECs are innervated by:

• Ant. & post. ethmoidal branches of nasociliary nerve from V1 & V2 via orbital branches from the pterygopalatine ganglion.

• ECs receive their blood supply through nasal branches of the sphenopalatine artery & branches of the ant. & post. ethmoidal arteries.

05/07/2021 33 Sphenoidal sinuses • Open into the roof of the NC via apertures on the post. wall of the spheno-ethmoidal recess. • Have average dimensions of: vertical height 2 cm; transverse breadth 1.8 cm; anteroposterior depth 2.1 cm • Arterial supply is via the posterior ethmoidal branch of the ophthalmic artery and nasal branch of the sphenopalatine artery Innervation is provided by: • Post. ethmoidal branch of the V1; • V2 via orbital branches from the pterygopalatine ganglion.

05/07/2021 34 MAXILLARY SINUSES • Are the largest of the paranasal sinuses. They occupy the bodies of the maxillae and communicate with the middle nasal meatus • Height-3.5cm, Breadth- 2.5cm, Diameter-3.2cm • Has Pyramidal shape with: – The apex which extends toward and often into the zygomatic bone. – The base formed by the inferior part of the lateral wall of the nasal cavity. – The roof formed by the floor of the orbit. – The floor of the is formed by the alveolar part of the maxilla. • Drained by the maxillary ostium (ostia), into the middle nasal meatus by way of the semilunar hiatus. • The arterial supply is mainly from superior alveolar branches of the maxillary artery. However, branches of the descending and greater palatine arteries supply the floor of the sinus • Innervation is from the anterior, middle, and posterior superior alveolar 05/07/2021nerves, which are branches of the maxillary nerve 35 Paranasal sinus drainage

05/07/2021 36 CLINICAL CORRELATES

• SINUSITIS/PANSINUSITIS • INFECTION OF THE ETHMOIDAL CELLS – Severe infections from this source may cause blindness because some posterior ethmoidal cells lie close to the optic canal, which gives passage to the optic nerve and ophthalmic artery. Spread of infection from these cells could also affect the dural nerve sheath of the optic nerve, causing optic neuritis. • TRANSILLUMINATION OF THE SINUSES – Transillumination of the maxillary sinuses – Transillumination of the Frontal sinuses • RELATIONSHIP OF THE TEETH TO THE MAXILLARY SINUS – The close proximity of the three maxillary molar teeth to the floor of the maxillary sinus poses potentially serious problems – Inflammation of the mucosa of the sinus is frequently accompanied by a sensation of toothache in the molar teeth.

05/07/2021 37 SPREAD OF INFECTION TO CRANIAL CAVITY • The middle meatus and hiatus semilunaris act as the prechamber for the anterior ethmoidal, frontal and maxillary sinuses, the osteomeatal complex, and can be readily examined with a fibreoptic endoscope. • The superior meatus and sphenoethmoidal recess acts as the prechamber for the posterior ethmoidal and sphenoidal sinuses. • Obstruction of these prechambers by swollen mucous membranes, polyps or tumours interferes with the ventilation of the sinuses and arrests mucus clearance, which in turn causes overgrowth of bacteria or viruses and consequent sinusitis

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