NOSE

 Nose and Paranasal Sinuses

NOSE

-The nose performs two functions:-

(a)respiratory passage: lined by respiratory mucosa, highly vascular and warms the inspired air.

(b)organ of smell: placed in the upper one-third of the nasal

cavity, lined by olfactory mucosa, contains receptors called olfactory cells.

-secretions of numerous serous glands make the

air moist; and the secretions of mucous glands trap

dust and other particles. Thus the nose acts as an air

conditioner where the inspired air is warmed, moistened and cleansed before it is passed on to the

delicate lungs.

EXTERNAL NOSE

-external nose has a skeletal framework that is partly bony and partly cartilaginous.

       _bones are

(a)nasal bones

(b)frontal processes of the maxillae.

         _cartilages are

(a)superior and inferior nasal cartilages

(b) septal cartilage

(c)small alar cartilages

 -skin over the external nose is supplied by the external nasal, infratrochlear and infraorbital nerves.

NASAL CAVITY

- nasal cavity extends from the external nares(nostrils) to the posterior nasal apertures,

-subdivided into right and left halves by the nasal septum.

-Each half has a roof, a floor, medial and lateral walls.

- (1)middle horizontal part is formed by (a)cribriform plate of the ethmoid.

   (2)anterior slope is formed by (a)nasal part of the frontal bone (b)nasal bone

(c)nasal cartilages.

(3)posterior slope is formed by (a) inferior surface of the body of the sphenoid bone

(4)floor is formed by

(a) palatine process of the maxilla

(b)horizontal plate of the palatine bone.

CLINICAL ANATOMY

-Common cold or rhinitis is the commonest infection

of the nose, occurs during change of the seasons.

- The paranasal air sinuses may get infected from the nose, example:-Maxillary sinusitis .

-😁Fracture of cribriform plate of ethmoid with tearing

off of the meninges may tear the olfactory nerve

rootlets. In such cases, CSF may drip from the nasal cavity. It is called CSP rhinorrhoea.

NASAL SEPTUM

-nasal septum is osseocartilaginous partition between the two halves of the nasal cavity. On each

side, it is covered by mucous membrane and forms the

medial wall of both nasal cavities.

Formation of Nasal Septum

- bony part is formed almost entirely by:

a. vomer

b. perpendicular plate of ethmoid.

 (😁however, other bones such as nasal spine of the frontal bone, rostrum of the sphenoid, nasal crests of the nasal, palatine and

maxillary bones also gives contribution in margins).

 -cartilaginous part is formed by:

a. septal cartilage

b. septa! processes of the inferior nasal cartilage.

- lower end is formed by fibrofatty tissue covered by skin. The lower margin of the septum

is called columella.

-septum has:

a. Four borders-superior, inferior, anterior and posterior.

b. Two surfaces- right and left.

Arterial Supply

-supplied by following artery

   (a)Anterosuperior part:- anterior and posterior ethmoidal arteries .

  (b)Anteroinferior part:-superior labial branch of facial artery.

 (c)Posterosuperior part:-sphenopalatine

artery. It is the main artery.

(d)Posteroinferior part:-few branches of greater palatine artery.

-all the above artery forms large capillary network called Kiesselbach' s plexus (little's area) which is common site of bleeding from the nose called epistaxis.

Venous Drainage

- veins form a plexus, plexus drains

anteriorly into the facial vein, and posteriorly through

the sphenopalatine vein to pterygoid venous plexus.

Nerve Supply

(1) General sensory nerves, arising from trigeminal nerve, are distributed to whole of the septum such as:-

 a. anterosuperior part: internal nasal branches of the anterior ethmoidal nerve.

b. anteroinferior part: anterior

superior alveolar nerve.

c. posterosuperior part: medial

posterior superior nasal branches of the pterygopalatine ganglion.

d. posteroinferior part: nasopalatine branch of the pterygopalatine ganglion.

(2)Special sensory nerves or olfactory nerves supplied to the upper part or olfactory area.

Lymphatic Drainage

-Anterior half: submandibular nodes.

-Posterior half: retropharyngeal and deep cervical nodes.

CLINICAL ANATOMY

- Little's area on the septum is common site of bleeding from the nose or epistaxis

- Pathological deviation of the nasal septum is often responsible for repeated attacks of common cold,

allergic rhinitis, sinusitis etc.

LATERAL WALL OF NOSE

-there is presence of three shelf-like bony projections called

conchne. It increase the surface area of nose for effective air-conditioning of the inspired air.

-lateral wall separates the nose from the:

a. orbit above

b. maxillary sinus below.

c. lacrimal sac and nasolacrimal duct in front

-The lateral wall can be subdivided into three parts.

a. small depressed area in the anterior part is called vestibule.

b. The middle part is known as the atrium of the middle meatus.

c. The posterior part contains the conchae. Spaces separating the conchae are called meatuses.

- lateral wall is partly bony, partly cartilaginous, and partly made up only of soft tissues.

Bony part consits of

a. Nasal.

b. Frontal process of maxilla

c. Lacrimal.

d. Labyrinth of ethmoid with superior and middle

conchae.

e. Inferior nasal concha, made up of spongy bone

only

f. Perpendicular plate of palatine bone

g. Medial pterygoid plate.

Cartilaginous part is formed by:

a. The superior nasal cartilage

b. The inferior nasal cartilage.

c. 3 or 4 small cartilages of the ala.

Its lower part is formed by fibrofatty tissue

covered with skin.

PARANASAL SINUSES

-They are air-filled spaces present within some bones around the nasal cavities.

-its function is to make skull lighter, warm up and humidify the inspired air. It also add resonance to the voice. Infection in it can alter the voice.

-They enlarge at the ages of 6 to 7 years, i.e. time of eruption of permanent teeth and then after puberty.

-they are :frontal, maxillary, sphenoidal and ethmoidal.

Frontal Sinus

-it lies in the frontal bone deep to the

 superciliary arch.

 -It opens into the middle meatus.

 -right and left sinuses are usually unequal in size,and rarely one or both may be absent.

 -(a)Arterial supply: Supraorbital artery.

 (b)Venous drainage: Into the supraorbital and superior ophthahnic veins.

 (c)Lymphatic drainage: To submandibular nodes.

 (d)Nerve supply: Supraorbital nerve.

Maxillary Sinus

-It lies in the body of the maxilla,

-it is the largest, and is pyramidal in shape.

- it is the first paranasal sinus to

 develop.

-it opens into the middle meatus.

-in an isolated maxilla, the opening of maxillary sinus is large. However, in the intact skull, the size of opening is reduced to 3 or 4 mm as it is overlapped by the following:

a. From above, by uncinate process of the ethmoid, and the descending part of lacrimal bone.

b. From below, by the inferior nasal concha.

c. From behind, by the perpendicular plate of the palatine bone . It is further reduced in size by the thick mucosa of nose.

-its roof is formed by the floor of orbit, and floor is formed by the alveolar process of maxilla.

-floor is marked by several conical elevations produced by the roots of upper molar and premolar

teeth.

-Arterial supply: Facial, infraorbital and greater palatine arteries.

Venous drainage: into the facial vein and the pterygoid plexus of veins.

Lymphatic drainage: into the submandibular nodes.

Nerve supply: Posterior superior alveolar branches from maxillary nerve and anterior and middle superior alveolar branches from infraorbital nerve

Sphenoidal Sinus

-it lie within the body of sphenoid bone.

- The two left and right sinuses are usually unequal in size.

- opens into the sphenoethmoidal recess.

 -each sinus is realted superiorly to the optic chiasma and the hypophysis cerebri And laterally to the internal carotid artery and the cavernous sinus.

-Arterial supply: Posterior ethmoidal and internal carotid arteries.

Venous drainage: Into pterygoid venous plexus and cavernous sinus.

Lymphatic drainage: To the retropharyngeal nodes.

Nerve supply: Posterior ethmoidal nerve and orbital branches of pterygopalatine ganglion.

Ethmoidal Sinuses

-they are numerous and lie within the labyrinth of the ethmoid bone.

 -They are completed

 (a)from above :- the orbital plate of the frontal bone,

 (b)from behind:- the sphenoidal conchae and the orbital process of the palatine bone,

 (c)anteriorly:- the lacrimal bone.

-sinuses are divided into 3 groups

 (a)anterior ethmoidal sinus:-

 *made up of 1 to 11 air cells,

  *opens into the anterior part of the hiatus semilunaris,

 * supplied by the anterior ethmoidal nerve and vessels.

 *lymphatics drain into the submandibular nodes

(b)middle ethmoidal sinus:-

*made of 1 to 7 air cells,

*open into the middle meatus.

*supplied by the anterior ethmoiidal nerve and vessels And the orbital branches of the pterygopalatine ganglion,

* Lymphatics drain into the submandibular nodes.

(c) posterior ethmoidal sinus:-

 *made of 1 to 7 air cells,

 *open into the superior meatus,

*supplied by the posterior ethmoidal nerve and vessels And the orbital branches of the pterygopalatine ganglion. *Lymphatics drain into the

retropharyngeal nodes.

CLINICAL ANATOMY

- Infection of a sinus is known as sinusitis. It causes headache and persistent, thick, purulent discharge from the nose. Diagnosis is done by radiography. A diseased sinus is opaque.

- - maxillary sinus is most commonly infected, It may be infected from the nose or from a caries tooth. In such case it is drained surgically by making an artificial opening near the floor by (a)Antrum puncture or (b)Caldwell-Luc operation.

- Frontal sinusitis and ethmoiditis can cause oedema of the lids.

- -Pain from ethrnoid air sinus may cause forehead pain.

 - Pain of maxillary sinusitis may cause

 - upper teeth and infraorbital skin pain.

✍According to Nepal Sanskrit University Past year Question.

https://t.me/MBBS_BAMS_NOTESnepal