Nasal Cavity and Paranasal Air Sinuses

Question 1

[16-minute video]: Dissection of Nasal Cavity and Paranasal Air Sinuses

Answer 1

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Question 2

State the features of the external nose.

Answer 2

1. Tip (or apex), the lower free end.
2. Root or bridge, the upper narrow part, which is continuous with the forehead.
3. Dorsum, a round border between tip and root where sides of the nose meet.
4. Nostrils or nares, the two piriform apertures at the broad lower end.
5. Ala, the lower flared part on the side of nose.
6. [Diagram 1]: it’ll show you the columella, [Diagram 2]

Question 3

Over the apex and alae of the nose, the skin is thicker and more adherent and contains large sebaceous glands, whose orifices are usually very distinct. The hypertrophy of these sebaceous glands gives rise to a lobulated tumor called the _________________.

Answer 3

rhinophyma

Question 4

The upper one-third of the external nose is bony. Name the bones contributing to formation of the bony compartment.

Answer 4

(a) two nasal bones (forming the bridge of the nose), and
(b) frontal processes of the maxillae.
[Diagram]

✶ The two nasal bones meet in the midline and rest on the upper part of the nasal process of the frontal bone. They are held together between the frontal processes of the maxillae. The bony part of external nose terminates in front and below as the piriform aperture.

Question 5

The cartilaginous framework of the nose is formed by five main cartilages and several additional tiny ones. List the five main cartilages of the nose.

Answer 5

✓ 2 lateral processes of septal nasal cartilage [also called superior lateral cartilages]
✓ Septal nasal cartilage which is a single median cartilage
✓ 2 major alar cartilages [also called inferior lateral cartilages]

[Diagram]: observe the lateral crus and medial crus of the major alar cartilages

Further notes:
✶ The cartilaginous framework is anchored to the piriform aperture by fibrous tissue.
✶ In addition to five main cartilages of the nose, there are two or more tiny cartilages, which lie above and lateral to major alar cartilage on either side and termed minor alar (or sesamoid) cartilages. They are of no functional and clinical significance.
✶ Nasal fractures: Because the nose is the most projecting part of the face, the fractures of nasal bones are common facial fractures.
✶ The medial and lateral crura of major alar cartilage maintain the patency of the nostril. The angle between the medial and lateral crura is variable, being acute in high narrow noses, and obtuse in low broad noses with flaring alae. This anatomical fact is of great significance in plastic surgery of the nose.

Question 6

Name the muscles of the external nose. Ensure you review their actions.

Answer 6

1. Procerus
2. Nasalis
3. Depressor septi nasi
4. [Diagram]

Question 7

Name the structures that form the roof of the anterior third of the nasal cavity.

Answer 7

nasal spine of the frontal bone, the nasal bone, and the junction of the septal and lateral cartilages
[Diagram: Roof of Nasal Cavity]

Question 8

Name the bones that form the margins of the choanae.

Answer 8

Medially: Vomer
Inferiorly: Horizontal plate of the palatine bone
Laterally: Medial pterygoid plate
Superiorly: Body of the sphenoid bone
[Diagram: Choanae]

Question 9

Name the bone that forms the roof of the middle third of the nasal cavity.

Answer 9

cribriform plate of the ethmoid bone
[Diagram: Roof of Nasal Cavity]

Question 10

Name the bone that forms the roof of the posterior third of the nasal cavity.

Answer 10

anterior surface of the body of the sphenoid
[Diagram: Roof of Nasal Cavity]

Question 11

Name the bones that form the floor of the nasal cavity.

Answer 11

the hard palate, of which the anterior three-fourths is formed by the palatine process of the maxillary bone, and the posterior fourth by the palatine bones
[Diagram: Floor of Nasal Cavity]

Question 12

The nasal septum froms the medial wall of the nasal cavity. Discuss its components.

Answer 12

The nasal septum is a median osseocartilaginous partition between the two nasal cavities. Its bony component is formed by:
(a) the perpendicular plate of ethmoid, which forms the posterosuperior part of the septum
(b) vomer, which forms the posteroinferior part of the nasal septum.

The cartilaginous part is formed by:
(a) septal cartilage, which forms the major anterior part of the septum and fits in the angle between the vomer and perpendicular plate of ethmoid, and
(b) septal processes of the two major alar cartilages.
[Diagram: Nasal Septum]

Question 13

Name the bones that form the lateral wall of the nasal cavity.

Answer 13

✓ nasal bone
✓ frontal process of the maxilla
✓ lacrimal bone
✓ conchae and labyrinth of ethmoid
✓ inferior nasal concha
✓ perpendicular plate of palatine
✓ medial pterygoid plate of sphenoid
[Diagram: Lateral Wall of the Nasal Cavity]

Question 14

Name the cartilages that form the lateral wall of the nasal cavity.

Answer 14

✓ the lateral nasal cartilage
✓ major alar cartilage
✓ minor alar cartilages
[Diagram: Lateral Wall of the Nasal Cavity]

Question 15

Outline the division of the lateral wall of the nasal cavity.

Answer 15

1. The anterior part presents a small depressed area, the vestibule that is lined by skin containing vibrissae (short, stiff, curved hair).
2. The middle part, known as the atrium of the middle meatus
3. The posterior part, which presents three scroll-like projections, the conchae or turbinates. The spaces separating the conchae are called meatuses.

Question 16

State the openings in the lateral wall of the nose at the following sites:
(a) sphenoethmoidal recesss
(b) superior meatus
(c) middle meatus on (I) bulla, (II) hiatus semilunaris
(d) inferior meatus

Answer 16

(a) sphenoethmoidal recess: opening of the sphenoidal air sinus
(b) superior meatus: opening of the posterior ethmoidal air sinuses
(c) middle meatus:
(I) bulla: opening of the middle ethomidal air sinuses
(II) hiatus semilunaris: Anterior part: opening of the frontal air sinus, Middle part: opening of the anterior ethmoidal air sinuses, Posterior part: opening of the maxillary air sinus
(d) inferior meatus: opening of the nasolacrimal duct (in the anterior part of meatus)

Ethmoidal bulla and hiatus semilunaris diagrams: [Diagram 1] [Diagram 2]

Question 17

The conchae of the nasal cavity are parts of which bones?

Answer 17

The superior and middle nasal conchae are projections from the medial surface of the ethmoidal labyrinth.
The inferior nasal concha is an independent bone.

Question 18

The nasal cavity is divided into the vestibule, the respiratory, and the olfactory areas. Briefly discuss the lining of the vestibule of the nasal cavity.

Answer 18

It is lined by the skin containing a large number of sebaceous glands and interlacing coarse hair—the vibrissae. [As the air passes through the nostrils the large particles of dust in the air are trapped by the vibrissae.]

Question 19

Briefly discuss the lining of the olfactory region of the nasal cavity.
[It comprises the upper third of the nasal cavity bounded above by the cribriform plate of the ethmoid bone, laterally by the superior nasal concha and medially by the upper one-third of the nasal septum.]

Answer 19

It is lined by the olfactory epithelium, which contains receptor cells for smell.
[Here the mucous membrane is paler in color.]

Question 20

Meatuses are the passages (recesses) beneath the overhanging conchae. They are visualized once conchae are removed. Inferior meatus is the largest. Superior meatus is the smallest. State the features that the middle meatus presents.

Answer 20

(a) Ethmoidal bulla (bulla ethmoidalis), a round elevation produced by the underlying middle ethmoidal sinuses.
(b) Hiatus semilunaris, a deep semicircular sulcus below the bulla ethmoidalis.
(c) Infundibulum, a short passage at the anterior end of middle meatus.
[Diagram: Features of middle meatus]

Question 21

Briefly discuss the lining of the respiratory region of the nasal cavity. [type of epithelium, vascularity, glands, cilia, functions]

Answer 21

✓ The lower two-third of the nasal cavity is lined by the respiratory epithelium i.e. pseudostratified ciliated columnar epithelium with goblet cells.
✓ The respiratory mucosa is highly vascular and contains a large number of cavernous spaces and sinusoids to warm the air.
✓ It contains a large number of serous and mucous glands. The secretion of the serous glands makes the air moist while the secretion of the mucous glands traps the dust and other particles.
✓ Cilia on the surface of the mucous membrane sweep the mucous posteriorly into the pharynx where it is swallowed and eliminated by the GIT.

Question 22

List the arteries that supply the nasal septum.
[Hint: septal branches of 2 branches of the ophthalmic artery, 2 branches of the 3rd part of the maxillary artery, and 1 branch of the facial artery]

Answer 22

1. Septal branch of the anterior ethmoidal artery [a branch of the ophthalmic artery]
2. Septal branch of the posterior ethmoidal artery [a branch of the ophtalmic artery]
3. Septal branch of the sphenopalatine artery [a branch of the maxillary artery]
4. Septal branch of the greater palatine artery [a branch of the maxillary artery]
5. Septal branch of the superior labial artery [a branch of the facial artery]
6. [Diagram: Arteries supplying the nasal septum]

Question 23

Discuss Little’s area.

Answer 23

Little’s area is an area in the anteroinferior part of the nasal septum just above the vestibule. It is highly vascular. Here, the septal branches of the anterior ethmoidal, sphenopalatine, greater palatine, and superior labial arteries anastomose to form a vascular plexus called Kiesselbach’s plexus.
This area of nasal septum is the commonest site of epistaxis (nosebleeding) in children and young adults, usually due to finger nail trauma following picking of the nose.
[Diagram: Little’s area]

Question 24

List the arteries that supply the lateral wall of the nasal cavity in the:
(a) anterosuperior quadrant
(b) posterosuperior quadrant
(c) anteroinferior quadrant
(d) posteroinferior quadrant

Answer 24

(a) anterosuperior quadrant: anterior ethmoidal artery, a branch of the ophthalmic artery
(b) posterosuperior quadrant: sphenopalatine artery, a branch of the maxillary artery
(c) anteroinferior quadrant: branches of the facial and greater palatine arteries
(d) posteroinferior quadrant: branches of greater palatine artery, which pierces the perpendicular plate of the palatine bone
[Diagram: Arterial supply of lateral wall of nasal cavity]

Question 25

Venous drainage of the nasal cavity
The veins draining the nasal cavity form plexus beneath the mucosa and in general accompany the arteries. The veins of nasal cavity drain into facial vein, pterygoid venous plexus, and pharyngeal venous plexus.

Answer 25

🙂

Question 26

Lymph from the anterior half of the nasal cavity is drained into ____(a)____ lymph nodes, and that from the posterior half is drained into the ____(b)____ lymph nodes.

Answer 26

(a) submandibular
(b) retropharyngeal

Question 27

List the nerves that supply the nasal septum.

Answer 27

(a) Internal nasal branch of the anterior ethmoidal nerve [a branch of the nasociliary; it supplies the anterosuperior part]
(b) Nasopalatine nerve [a branch of pterygopalatine ganglion—supplies the posteroinferior part]
(c) Medial posterosuperior nasal branches of the pterygopalatine ganglion [supply the posterosuperior part]
(d) Nasal branch of greater palatine nerve [supplies the
posterior part]
(e) Anterior superior alveolar nerve [a branch of maxillary
nerve—supplies the anteroinferior part]
(f) Olfactory nerves supply the upper one-third
[Diagram: Nerve Supply of Nasal Septum]

Question 28

List the nerves that supply the lateral wall of the nasal cavity.

Answer 28

(a) Anterior ethmoidal nerve (from ophthalmic)—supplies the anterosuperior quadrant.
(b) Anterior superior alveolar nerve, a branch of infraorbital nerve (from maxillary)—supplies the anteroinferior quadrant.
(c) Posterior superior lateral branches, of pterygopalatine ganglion—supply posterosuperior quadrant.
(d) Nasal branches of greater palatine nerve, (from pterygopalatine ganglion)—supply posteroinferior quadrant
(e) Olfactory nerves—supply the upper part (one-third) just below the cribriform plate of ethmoid up to the superior concha.
[Diagram: Nerve Supply of Lateral Wall of Nasal Cavity]

Question 29

Briefly discuss the autonomic innervation of the nasal cavity.

Answer 29

The nasal cavity receives both parasympathetic and sympathetic supply from the Vidian nerve (nerve of pterygoid canal) through the pterygopalatine ganglion.
The parasympathetic fibres supply nasal glands and control nasal secretion. The sympathetic fibres, on stimulation, cause vasoconstriction.
[Diagram: Autonomic Innervation of the Nasal Cavity]

Question 30

Name the four paranasal air sinuses and their relation to the orbit.

Answer 30

(a) Frontal air sinus, located superior to the orbit
(b) Maxillary air sinus, located inferior to the orbit
(c) Ethmoidal air sinuses, located medial to the orbit
(d) Sphenoidal air sinus, located posterior to the orbit
[Diagram 1] [Diagram 2] [Diagram 3]

Question 31

State the type of epithelium that lines the cavities of the paranasal air sinuses.

Answer 31

pseudostratified ciliated columnar epithelium

Question 32

State four functions of the paranasal air sinuses.

Answer 32

1. They make the skull lighter.
2. They add resonance to the voice.
3. Act as air conditioning chambers by adding humidity and heat to the inspired air.
4. Aid in the growth of facial skeleton after birth.

Question 33

Here are some CT images of the paranasal air sinuses.

Answer 33

[Image 1]: axial view showing the ethmoid and sphenoid sinuses
[Image 2] [Image 3]

Question 34

Explain the classification of the paranasal air sinuses.

Answer 34

The paranasal air sinuses are divided into an anterior and a posterior group.
The anterior group includes those sinuses which drain into the middle meatus i.e. the frontal, maxillary and anterior and middle ethmoidal air sinuses.
The posterior group includes those sinuses which do not drain into the middle meatus i.e. posterior ethmoidal and sphenoidal air sinuses.

Question 35

Describe the course of the maxillary nerve.

Answer 35

It arises from the convex anterior border of the trigeminal ganglion, pierces the trigeminal cave of dura to reach the lower part of the lateral wall of the cavernous sinus. The nerve leaves the middle cranial fossa through foramen rotundum to reach the pterygopalatine fossa. It traverses straight in the upper part of the fossa and enters the orbit through inferior orbital fissure, hence it is called infraorbital nerve. The infraorbital nerve (in fact a continuation of maxillary nerve) runs forward along the floor of the orbit in the infraorbital groove and canal in succession and appears on the face, through infraorbital foramen. Therefore in its course the maxillary nerve traverses four regions in succession: the middle cranial fossa, the pterygopalatine fossa, the orbit and the face.

Question 36

State the branches and distribution of the maxillary nerve in the:
A. middle cranial fossa
B. pterygopalatine fossa

Answer 36

A. Meningeal branch, which supplies the dura mater of the middle cranial fossa.
B.
1. Ganglionic (communicating) branches, two in number to pterygopalatine ganglion.
2. Zygomatic nerve enters the orbit through inferior orbital fissure and divides on the lateral wall of the orbit into:
(a) a zygomaticotemporal branch, which passes through a foramen in the zygomatic bone to supply the skin of the temple, and
(b) a zygomaticofacial branch, which passes through the foramen in the zygomatic bone to supply the skin of the face.
3. Posterior superior alveolar nerve enters the one or two foramina on the posterior surface of the body of maxilla and supplies the mucus membrane of the maxillary air sinus. Then it breaks up to form superior dental plexus, which supplies the molar teeth and adjoining part of the gum.

Question 37

State the branches and distribution of the maxillary nerve:
A. In the orbit
B. On the face (given off after the infraorbital nerve exits the orbit through the infraorbital foramen)

Answer 37

A.
1. Middle superior alveolar nerve passes downward and forward along the lateral wall of the maxillary sinus, joins superior dental plexus and supplies the premolar teeth.
2. Anterior superior alveolar nerve runs in the anterior wall of the maxillary sinus through a bony canal called canalis sinuosus and divides into dental and nasal branches:
(a) The dental branches join the superior dental plexus and supply the canine and incisor teeth.
(b) The nasal branches appear in the lateral wall of the inferior meatus and supply the mucus membrane of the lateral wall and floor of the nasal cavity.
B.
1. Palpebral branches turn upwards and supply the skin of the lower eyelid.
2. Nasal branches supply the skin of the side of nose and the mobile part of the nasal septum.
3. Superior labial branches supply the skin and mucus membrane of the upper lip.

Question 38

The pterygopalatine ganglion (ganglion of hay fever) is the largest parasympathetic peripheral ganglion. State the roots of this ganglion.

Answer 38

1. Motor or parasympathetic root derived from nerve of pterygoid canal [How is this nerve formed?].
2. Sympathetic root derived from sympathetic plexus around internal carotid artery via nerve of pterygoid canal.
3. Sensory root derived from maxillary nerve.

Question 39

The branches of the pterygopalatine ganglion are actually the branches of maxillary nerve, which passes through the ganglion without relaying. While passing through the ganglion, they incorporate the parasympathetic and sympathetic fibres of the ganglion. List the four sets of branches provided by the ganglion, and area of distribution.

Answer 39

1. Orbital branches: supply orbital periosteum, ethmoidal air sinuses, and secretomotor fibres to the lacrimal gland.
2. Palatine branches:
   Greater palatine nerve - supply posteroinferior quadrant of the lateral wall of the nose.
   Lesser palatine nerve - supply secretomotor fibres to mucus membrane and glands on the inferior surface of soft palate and hard palate.
3. Nasal branches:
   Posterior superior nasal nerves - lateral set supply lateral wall of nasal cavity, those of medial set supply roof and nasal septum.
   Sphenopalatine/nasopalatine nerve - the longest branch of the medial set of the posterior superior nasal nerves. Supplies the anterior part of the hard palate.
4. Pharyngeal branch: passes through palatovaginal canal and supply the nasopharynx.

Question 40

State the clinical relevance of the maxillary air sinus. (Note: Think about its opening into the nasal cavity and the location of the maxillary air sinus. You may also wanna think about gravity)