Nasal cavities

Question 1

What are nares

Answer 1

Actual meatus (hole)

Surrounded by hairless skin

Supported by nasal cartilages

Question 2

What is nasal vestibule

Answer 2

Opening of nasal cavity

Contains nasolacrimal duct

Question 3

Bovidae external nares features

Answer 3

Nostrils surrounded by smooth hairless nasolabial plate
Stratified cornified epithelium
Nasolabial glands create moisture

Question 4

Equidae external nares features

Answer 4

No ventral nasal cartilage

Incomplete cartilaginous ring
Distensible nostrils

Alar cartilages
Ventral ‘true’ nostril
Dorsal ‘false’ nostril

Muscles innervated by facial nerve & supplied by facial artery

Question 5

Carnivoridae external nares features

Answer 5

Nasal plate divided by median groove

Secretions from lateral nasal glands

Question 6

Suidae external nares features

Answer 6

Small nostrils on snout

Highly sensitive

Contains os rostrale (extra bone)

Question 7

Aves external nares features

Answer 7

Slit like openings

Operculum:
Overhanging bony flap
Wide communication between nasal cavity & pharynx

Question 8

Describe structure of the nasal cavity

Answer 8

Extends from nostrils to cribiform plate of ethmoid bone

Divided by nasal septum

Further divided into nasal meatuses by nasal conchae
Further increases nasal surface area
Highly vascular structure

Question 9

Describe the division of the nasal cavity

Answer 9

Divided by scrolls of turbinate bone to form nasal conchae

Simple in horse

Complex in dog
Smelling & filtering important
Complex folding of bones increases ability to smell & warm air
Pugs have problems with turbinates, plates & nostrils – everything bunched up instead of spread out

Question 10

Define turbinates, conchae & meatus

Answer 10

Turbinates:
Curled bone with mucosal lining

Conchae:
Long thin bone covered by nasal mucosa
Coiled up like paper roll

Meatus:
Gaps between them

Question 11

What are the functions of the nasal cavity

Answer 11

Conduction & preparation of inspired air
Moisten air
Warm air
Filter particles

Heat exchange for cooling brain

Olfaction

Question 12

What are the 4 meatus & where do they run to

Answer 12

Ventral runs into common

Question 13

What are the functions of respiratory epithelium

Answer 13

Regulation of air flow

Cleaning (cilia)

Humidification

Warming (variable blood perfusion)

Question 14

Role of the ethmoturbinates

Answer 14

Olfaction

Ethmoturbinates extend rostrally from ethmoid bone

Covered with respiratory epithelium

Also contains olfactory sensory neurones

Sniffing alters normal airflow to bring air into contact with ethmoturbinates

Supplied by olfactory nerve

Question 15

What is the vomeronasal organ

Answer 15

Accessory olfactory sense organ

Contained within hard palate

Question 16

Explain path of airflow

Answer 16

1. Air enters nostrils
2. Air passes through nasal vestibule
   Large particles filtered here
3. Air flows through nasal cavity
   Divided into 2 sides by nasal septum
   Nasal cavity lined with mucous membranes & cilia which trap smaller particles
4. Air passes over turbinates
   Warm & humidify air
5. Air reaches nasopharynx & from here goes to larynx, trachea & down into lungs

Question 17

What are paranasal sinuses

Answer 17

Arise as invaginations into each bone

Contain respiratory epithelium
Innervated by ophthalmic & maxillary branches of trigeminal nerve & sensory nerve of face

Question 18

Where does the maxillary sinus drain into

Answer 18

Drains into middle meatus
Usually narrow slit so drainage is difficult

In cattle extends into palatine bone
Palatomaxillary sinus

Question 19

What is the frontal sinus

Answer 19

3-5 unconnected compartments
Drain into ethmoidal region

Cattle have 5, caudal compartment (green) largest & leads to cornual process & pneumatises horn

Dogs have 3 (lateral largest)

Question 20

Label the image & describe equine paranasal sinuses

Answer 20

Appear more complex but are actually simple

7 individual sinuses

All drain via common ostium

Question 21

What is the nasolacrimal duct

Answer 21

Connects lacrimal sac to nasal cavity

Drains tears into nasal cavity

Runs with maxilla & maxillary sinus

Ends in nostril in horse

Ends in nasal cavity in dogs

Question 22

Describe connection between horns & sinuses

Answer 22

Frontal sinus communicates with horns

During horn removal sinus is exposed
Predisposed to infection & nasal discharge

Question 23

Describe innervation & vascular supply of horns

Answer 23

Innervation:
Trigeminal nerve
Cornual nerve (nerve block)
Cornual branch of infratrochlear (nerve block)
Frontal nerve (in some animals)

Vascular supply:
Cornual artery (from maxillary artery)
Very vascular

Question 24

Where are the dorsal, ventral, lateral & caudal nasal cavities

Answer 24

Question 25

Label structures 1-7

Answer 25

1. nasal septum
2. dorsal meatus
3. middle meatus
4. ventral meatus
5. common meatus
6. dorsal concha
7. ventral concha

Question 26

How do secretions drain from paranasal sinuses in horses

Answer 26

1. frontal & dorsal conchal sinus
2. frontomaxillary aperture
3. caudal maxillary sinus & rostral maxillary sinus
4. nasomaxillary sinus

Question 27

Label the structures

Answer 27

1. dorsal concha
2. ventral concha
3. ethmoidal concha
4. vomer bone
5. hard palate
6. soft palate
7. orifice of auditory tube
8. stylohyoid bone
9. medial retropharyngeal lymph nodes
10. cricoid cartilage
11. cricoid cartilage
12. thyroid cartilage
13. basihyoid bone