Nasal cavities Flashcards
What are nares
Actual meatus (hole)
Surrounded by hairless skin
Supported by nasal cartilages
What is nasal vestibule
Opening of nasal cavity
Contains nasolacrimal duct
Bovidae external nares features
Nostrils surrounded by smooth hairless nasolabial plate
Stratified cornified epithelium
Nasolabial glands create moisture
Equidae external nares features
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
Carnivoridae external nares features
Nasal plate divided by median groove
Secretions from lateral nasal glands
Suidae external nares features
Small nostrils on snout
Highly sensitive
Contains os rostrale (extra bone)
Aves external nares features
Slit like openings
Operculum:
Overhanging bony flap
Wide communication between nasal cavity & pharynx
Describe structure of the nasal cavity
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
Describe the division of the nasal cavity
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
Define turbinates, conchae & meatus
Turbinates:
Curled bone with mucosal lining
Conchae:
Long thin bone covered by nasal mucosa
Coiled up like paper roll
Meatus:
Gaps between them
What are the functions of the nasal cavity
Conduction & preparation of inspired air
Moisten air
Warm air
Filter particles
Heat exchange for cooling brain
Olfaction
What are the 4 meatus & where do they run to
Ventral runs into common
What are the functions of respiratory epithelium
Regulation of air flow
Cleaning (cilia)
Humidification
Warming (variable blood perfusion)
Role of the ethmoturbinates
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
What is the vomeronasal organ
Accessory olfactory sense organ
Contained within hard palate
Explain path of airflow
- Air enters nostrils
- Air passes through nasal vestibule
Large particles filtered here - Air flows through nasal cavity
Divided into 2 sides by nasal septum
Nasal cavity lined with mucous membranes & cilia which trap smaller particles - Air passes over turbinates
Warm & humidify air - Air reaches nasopharynx & from here goes to larynx, trachea & down into lungs
What are paranasal sinuses
Arise as invaginations into each bone
Contain respiratory epithelium
Innervated by ophthalmic & maxillary branches of trigeminal nerve & sensory nerve of face
Where does the maxillary sinus drain into
Drains into middle meatus
Usually narrow slit so drainage is difficult
In cattle extends into palatine bone
Palatomaxillary sinus
What is the frontal sinus
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)
Label the image & describe equine paranasal sinuses
Appear more complex but are actually simple
7 individual sinuses
All drain via common ostium
What is the nasolacrimal duct
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
Describe connection between horns & sinuses
Frontal sinus communicates with horns
During horn removal sinus is exposed
Predisposed to infection & nasal discharge
Describe innervation & vascular supply of horns
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
Where are the dorsal, ventral, lateral & caudal nasal cavities
