The Upper Respiratory Passageways - Nose, Nasal Vestibule and Nasal Cavity (Dog)

M.9,W.1,L.1

what does the repiratory system consist of?

1. ancillary organs

2. the lungs

3. the diaphragm

• plus muscles of the thoracic body wall

what are ancillary organs?

passageways leading to and from the lungs

list the ancillary organs

• nose

• Nasal vestibule

• nasal cavity

• nasopharynx

• larynx

• trachea

define lungs

passageways within each lung leading to exchange tissue

what is the main muscle of respiration?

diaphragm

what does the diaphragm form?

partition between thorax and abdominal cavities

what are general functions of the respiratory system?

1. gaseous exchange

2. vocalization/phonation

3. olfaction

4. contributes to temp regulation and acid-base balance

what is the general function of ancillary organs in terms if gaseous exchange?

volume regulation and air conditioning

what is the general function of lung alveoli in terms of gaseous exchange?

blood gas barrier

what are the lateral bony boundaries of the nasal cavity?

• lacrimal

• incisive

• maxilla

• zygomatic

what are the ventral bony boundaries of the nasal cavity?

• palatine

• maxilla

• incisive

what are the dorsal bony boundaries of the nasal cavity?

• frontal

• nasal

what are the caudal bony boundaries of the nasal cavity?

Cribiform plate of Ethmoidal bone

what are nostrils?

external nares

what are nostrils divided by?

Philtrum

describe the skin of a nose

glandular, thick, hairless, pigmented and grooved

where do the secretions that moisten the nose come from?

• lacrimal glands (via nasolacrimal duct)

• lateral nasal glands

what provides blood supply to the nose area?

Sphenopalatine artery

what are facial expression muscles responsible for?

movement of muzzle region including nose

list the muscles involved in facial expression

• Superficial M. - Levator nasolabialis

• Deep M. - Levator labii maxillaris

• M. - Caninus

what is the motor supply for facial expression?

Facial Nerve (VII)

what is the sensory innervation of the nose?

infra-orbital nerve (br. Trigeminal (V))

what structure do the nostrils lead to?

nasal vestibule

what does the nasal vestibule extend beyond?

extends beyond the bony skull

what does the nasal septum divide?

divides the vestibule into two separate passageways that lead into nasal cavity which is also divided into right and left sides

describe the makeup of the nasal septum rostrally vs caudally

cartilage - rostrally

becomes bony at caudal attachment (ethmoid bone)

what supports the nasal septum ventrally?

the Vomer

what does the Vomer extend beyond and what does it attach to?

continues beyond caudal extent of hard palate

attaches to base of cranium

list the features of the nasal vestibule

1. 3 mucosal folds in each vestibule

2. Nasolacrimal (NL) duct

3. Lateral nasal gland ducts

list the three mucosal folds found in each nasal vestibule and which is the largest?

1. Alar fold (largest)

2. Dorsal fold

3. Basal fold

what are dorsal and ventral conchae?

fragile, scrolled bony networks covered in very vascular mucosa

what is the function of dorsal and ventral conchae?

‘air conditioning’ (direct, slow, clean, warm & moisten)

what kind of epithelium does ethmoidal conchae have?

olfactory epithelium

what is the function of ethmoidal conchae and middle concha?

smell

after air enters the nasal cavity, what structure is it directed through?

Conchal labyrinth via a series of passageways called MEATUSES

what do the nasal cavities directly link with?

paranasal sinuses

what are paranasal sinuses?

air-filled spaces within skull bones that border each nasal cavity

what do the paranasal sinuses communicate with?

the nasal cavity

what kind of epithelium are the the paranasal sinuses lined with?

respiratory epithelium

list the functions of the paranasal sinuses?

1. lighten the head

2. protect the cranium

3. increase surface area for muscle attachment

4. contribute to resonance

how many compartments is the frontal sinus?

several compartments

why are the frontal sinuses clinically relevant in canines?

Infection (ex: Aspergillosis)

Is the maxillary recess (in carnivores) a true sinus?

NOT A TRUE SINUS

list two other features of the nasal cavities

1. Vomeronasal organ (VNO)

2. Incisive ducts

describe the VNO (what it is, location, mucosa, function)

• tubular structure

• lined with specialized olfactory mucosa

• detects pheromones

• located in ventral nasal meatus on either side of nasal septum

describe the incisive ducts (what they connect and function)

• connect oral cavity (via incisive papilla) to vomeronasal organ

• may allow tiny amounts of oral fluid to reach VNO (so it can chemically “evaluate” those substances)

list the boundaries of the Nasopharynx

1. Internal Nares (choana) - rostral

2. Soft Palate - ventral

3. Base of Cranium - dorsal

4. Palatopharyngeal arch - caudal

list the two features of the Nasopharynx

1. Openings of the Auditory tubes

2. The Pharyngeal tonsil

what does the opening of the auditory tube lead to?

tympanic bulla / middle ear

describe the auditory tubes (lined by and function)

• lined by respiratory epithelium

• equalization of pressure

what is the pharyngeal tonsil apart of?

part of retro-pharyngeal lymph center

Purpose of retro-pharyngeal lymph center?

immuno-surveillance (lymphatic tissue)

what is the role of the common pharynx / laryngopharynx?

passage for both breathing and swallowing

what forms the wall of the pharynx and what do they do?

pharyngeal muscles; constrict, dilate and shorten

what is the larynx supported by and which direction does it move during swallowing?

• hyoid apparatus

• moves rostrally

what is the Aditus?

• entrance to larynx

• laryngeal inlet

• entrance point in which air will pass to the trachea