Nasal Cavity and Paranasal Sinuses

Question 1

What is the nasal cavity composed of externally?

Answer 1

bone
cartilage
muscle

Question 2

What are the bones of the external nose?

Answer 2

extensions of the skull
* Nasal bones
* Frontal processes of
maxillae

Question 3

What are the cartilages of the nose?

Answer 3

• Septal cartilage
• Major & minor alar
  cartilages

Question 4

What are the muscles overlying the bone and cartilage?

Answer 4

• Nasalis
• Depressor septi nasi
• Levator labii superioris alaeque nasi

Question 5

What are the paired cavities seperated by?

Answer 5

nasal septum

Question 6

How is the nasal cavity seperated from the oral cavity?

Answer 6

hard palate (floor)

Question 7

What are the anterior apertures of the nasal cavity?

Answer 7

nares

Question 8

What are the posterior apertures of the nasal cavity?

Answer 8

choanae
which open into the nasopharynx

Question 9

What receptors does the nasal cavity have?

Answer 9

olfactory responsible for smell

Question 10

How is inhaled air warmed, moistened and filtered?

Answer 10

by the mucous membrane of the nasal cavity

Question 11

Where does olfaction occur?

Answer 11

in upper part of the nasal cavity where airflow is diverted especially when “sniffing ”

Question 12

What is the hard palate made of?

Answer 12

• Palatine process of maxilla
• Horizontal plate of the palatine bones

Question 13

What is at the floor of the cavity?

Answer 13

hard palate
nares
incisive canals (nasopalatine canals)
nasal crest

Question 14

What do the incisive canals connect and what do they contain?

Answer 14

• Connection between nasal & oral cavities
• Contains the nasopalatine nerve & greater palatine artery

Question 15

What is the nasal crest?

what attaches to it

Answer 15

• Ridge formed at the connection of paired maxillae & palatine bones
• Attachment of the vomer of the nasal septum

Question 16

What is the medial wall of the nasal cavities?

Answer 16

nasal septum

Question 17

What forms the nasal septum?

Answer 17

• Septal cartilage
• Perpendicular plate of
  the ethmoid bone
• Vomer

Question 18

What is septal deviation and how is it corrected?

Answer 18

• Septum is displaced away from the midline
• The extent of displacement can range from mild to severe
• This can be due to a birth defect or, most commonly, caused by injury
• It means that the nasal cavity on one side is obstructed causing symptoms such as snoring, difficulty breathing through the nose, nosebleeds
• It can be corrected surgically

Question 19

Why is the roof narrower than the floor?

Answer 19

due to the wedge shape of the nasal cavity

Question 20

What is the highest point of the cavity formed by?

Answer 20

cribriform plate of the ethmoid bone

Question 21

What does the cribriform plate have?

Answer 21

many foramina to allow the passage of the olfactory nerves into the nasal cavity from the olfactory bulb on the base of the brain

Question 22

What is the anterior roof formed by?

Answer 22

• Nasal bones
• Nasal spine of the frontal bone

Question 23

What is the posterior roof formed by?

Answer 23

sphenoid bone

Question 24

What are olfactory nerves anchored by?

Answer 24

by dura as they pass through the cribriform plate

Question 25

Where are olfactory nerves distributed to?

Answer 25

to the roof & upper aspect of the nasal cavity

Question 26

What can trauma/pathologies causing the brain and olfactory bulb to move do?

Answer 26

may tear the olfactory nerves causing anosmia

Question 27

What can fractures of the cribriform plate cause?

Answer 27

CSF rhinorrhoea

Question 28

What are the structures of the lateral wall?

Answer 28

nasal bone lacrimal bone lateral process of septal cartilage major alar cartilage minor alar cartilage inferior concha middle concha superior concha perpendicular plate of palatine bone medial petrygoid plate of sphenoid bone ethmoid

Question 29

What are the features of the ethmoid bone?

Answer 29

the ethmoid bone is a major component of the nasal cavity It has a left & right ethmoidal labyrinth with a single, midline perpendicular plate & cribriform plate The ethmoidal labyrinth projects two of the three conchae into the nasal cavity; the superior & middle conchae

Question 30

What is underneath the conchae?

Answer 30

the corresponding meatus

Question 31

What does the structural arrangement of the conchae create?

Answer 31

various air streams, increasing the surface area between the lateral wall of the nasal cavity & the inspired air

Question 32

What is the arterial supply of nasal cavity? | external carotid, internal carotid/opthalmic artery

Answer 32

**ECA** Maxillary - sphenopalatine, greater palatine Facial - superior labial, lateral nasal **ICA** Ophthalmic - anterior and posterior ethmoidal

Question 33

What do the anterior and posterior ethmoidal arteries form and why is this area significant?

Answer 33

These vessels form many anastomoses, especially in the anterior septal region & this is an area in which nosebleeds can commonly occur

Question 34

What is the venous drainage of the nasal cavity?

Answer 34

Veins tend to follow arteries * Veins that follow arteries of the maxillary artery drain into the pterygoid plexus * Veins that follow arteries of the facial artery drain into the facial vein * Veins that follow ethmoidal arteries drain into the ophthalmic vein & subsequently the cavernous sinus

Question 35

What are the paranasal sinus and what is their role?

Answer 35

frontal, ethmoidal, maxillary and sphenodial * Hollow air-filled cavities * Increase surface area aiding efficient “air conditioning” * Lighten the skull * Add resonance to the voice

Question 36

What shape is the maxillary sinus, where does it drain and why is this clinically significant?

Answer 36

pyramid shaped * The maxilla sinus drains into the middle meatus at the semilunar hiatus * The drainage opening for the maxillary sinus is positioned high up, near the top of the sinus, which means the sinus floor is lower than its drainage point. * As a result the maxillary sinus is prone to chronic infections as gravity doesn't assist much in draining the mucus out of the sinus.

Question 37

What could extration of maxillary molar teeth cause? | what is this called?

Answer 37

might damage the maxillary sinus floor * This could create an opening between the maxillary antrum & oral cavity (oro-antral communication) with the potential of causing infection

Question 38

Where do the middle ethmoidal cells open?

Answer 38

ethmoidal bulba

Question 39

Where do posterior ethmoidal cells open?

Answer 39

lateral wall of superior meatus

Question 40

Where does the sphenoid sinus drain?

Answer 40

spheno ethmoidal recess

Question 41

Where do the anterior ethmoidal cells and frontal sinus drain?

Answer 41

infundibulum opening of frontonasal duct