Nasal cavities

Question 1

what are the functions of the nasal cavities

Answer 1

conduction and preparation of inspired air:
- moistens
- warms
- filters and traps particles

heat exchange and cooling for the brain:
- airflow cools venous blood
- subsequent countercurrent flow with arteries cools arterial blood going to the brain

olfaction:
- caudal regions of the turbines covered by olfactory epithelium

Question 2

describe the landmarks that the nasal cavity is bordered by

Answer 2

dorsally: nasal bones
ventrally: hard palate
laterally: incisive bone and maxilla
rostrally: nares (nostrils)
caudally: nasopharynx
axially: nasal septum (vertical through nasal cavity

Question 3

how are the nostrils supported

Answer 3

cartilage attached to nasal septum
(cows have a cartilagenous ring)

Question 4

compare the nares of the horse to the cow

Answer 4

cattle:
- nostrils surrounded by smooth hairless nasolabial plate (stratified cornified epithelium with serous glands to creat moisture called nasolabial glands)

horses:
- no ventral nasal cartilage
- incomplete cartilagenous ring to allow for distensible nostrils to help pass air through
- alar cartilages (form comma shaped nostrils) make a true nostril ventrally and a false nostril dorsally
- have significant ability to distend nostril to improve airflow

Question 5

what muscles control nostril dilation, what are they innervated by and what artery provides blood supply

Answer 5

• levator nasolabilais (contracts to bring lateral nare outward)
• caninus
• transverse nasi (pulls axial aspect inward to dilate)

all innervated by facial nerve
all supplied by the facial artery

Question 6

what gland moistens the nose of the dog and cat

Answer 6

lateral nasal gland

Question 7

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what is the name of the median groove that divides the nasal plate of the dog and cat

Answer 7

philtrum

Question 8

what are the complications that brachycephalic breeds face

Answer 8

BOAS causes:
- stenotic nares
- elongated an thickened soft palates
- enlarged tongues
- narrow tracheas

affects QOL:
- increased breathing and noise
- coughing and shortness of breath
- sleep apnoea
- exercise intolerance

Question 9

describe the species adaptation of the nasal cavity of a pig

Answer 9

• small nostrils on flat, mobile snout
• highly sensitive
• have rostral boney plate

Question 10

describe the species adaptations of nares in birds

Answer 10

• slit like openings
• operculum (overhanging bony flap)

Question 11

What is the nasal vestibule

Answer 11

• the opening of the nasal cavity
• contains the opening of the nasolacrimal duct
• recieves nasal gland secretions in dogs

Question 12

Map nasal osteology

Answer 12

dorsal: nasal bones (1)
lateral: incisive bones (2) and Maxilla (3)
ventral: palatine bones
caudal: ethmoidal bone
axial: nasal septum

Question 13

describe the nasal cavities

Answer 13

• extends from nostrils to cribiform plate of ethmoid bone
• divided into left and right sides by nasal septum
• each side then further divided by nasal conchae

Question 14

what are nasal conchae

Answer 14

• scrolls of turbinate bone covered in mucosa
• further increase nasal surface area
• highly vascular (helps warm air)

Question 15

discuss the differences between canaine conchae and equine conchae

Answer 15

• canine conchae is highly complex and densely packed
• equine conchae is more spaced out, provinding larger spaces for air to flow

dont stick things in dogs noses - will bleed and break

Question 16

what are the nasal meatus

Answer 16

• nasal conchae divide nasal cavity into three separate passages: dorsal, ventral and middle meatus
• simple in horses, more complex in dogs

Question 17

why are the nasal cavities of dogs more complex than those of horses

Answer 17

• horses are obligate nasal breathers, while dogs can breath through their mouths
• olfaction

Question 18

label

Answer 18

blue: dorsal meatus
red: middle meatus
pink: ventral meatus

Question 19

what nasal meatus do you want to pass a nasal tube through

Answer 19

ventral meatus - middle and dorsal are too small

Question 20

label and describe the types of epithelium you would expect to find in these regions

Answer 20

a: vestibule: transition from integument to mucous membrane
b: nasal cavity: respiratory epithelium
c:. caudodorsal part of the ethmoidal conchae = olfactory epithelium
d: vomernasal organ (secondary olfaction organ for pheremone detection)

Question 21

describe the respiratory epithelium and its functions

Answer 21

• pseudostratified
• ciliated
• columnar
• contains goblet cells

functions:
- regulation of air flow by erectile tissue
- cleaning
- humidification
- warming
- protection reflexes

Question 22

What is the role of turbinates in olfaction

Answer 22

• The ethmoturbinates extend rostrally from the ethmoid bone
• covered with respiratory epithelium
• also contain olfactory sensory neurones
• Sniffing alters the normal airflow to bring the air into contact with the ethmoturbinates.

Question 23

what does the olfacttory region of the nasal cavity contain

Answer 23

• Olfactory cells.
• Non-motile- cilia-like structures: olfactory receptors, exposed dendrite on the mucosal surface detects chemicals. Olfactory neurones are continuously renewed due to the presence of neural stem cells in the basal layer. Axons collect in bundles in lamina propria.
• Cranial nerve I (olfactory nerve)- axons group into bundles, bundles penetrate the cribriform plate, enter olfactory lobe of brain.

Question 24

what is the vomernasal organ

Answer 24

• accessory olfactory sense organ
• contained within the hard palate
• unique chemoreceptors distinct from other olfactory organs (may play a role in pheremone detection
• associated with the flehmen response (lip curling in horses)

Question 25

what structures cause the most air flow resistance

Answer 25

nasal cavity, pharynx and larynx
resistance = length/radius^4