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Cheatography

VETS2011 - RESPIRATORY ANATOMY Cheat Sheet (DRAFT) by

Structure and function 1

This is a draft cheat sheet. It is a work in progress and is not finished yet.

GENERAL CHARAC­TER­ISTICS OF RESPIR­ATORY SYSTEM

primary function
oxygenate blood, excrete CO2
secondary functions
- olfaction
- phonation
- temper­ature regulation
 
structural evolution
→ deny partic­ulate matter
→ maximize surface area for gas exchange
→ warm and humidify air

COMPONENTS MAMMALIAN RESPIR­ATORY SYSTEM

conducting component
- nose, nasal cavity, nasoph­arynx
- larynx
- trachea, bronchi, bronch­ioles
 
respir­atory component
- respir­atory bronch­ioles
- alveolar ducts and alveolar sacs
- alveoli
 
pumping mechanism
- diagram
- rib cage
- neurol­ogical control

conducting component - NOSE

consists of
- external nose
- nasal cavities
- paranasal sinuses
supported by bone and cartilage
lined by mucous membrane

nose - EXTERNAL NOSE

specific to each species
affected by
- shape of supporting lateral nasal cartilages
- skin type around nose
supported by lateral nasal cartilages
- dorsal and ventral
- may have accessory cartilage
- extensions of nasal septum

nose - EXTERNAL NOSE

dog, cat, sheep, goat
- cartilage complete laterally
- thick, hairless skin or planum nasale confined to area around nostrils
- well-d­efined philtrum
 
pig
- cartilage complete laterally
- extra support by rostral bone medially
- planum rostrale continuous with upper lip
- small philtrum
 
ox
- cartilage complete laterally
- planum nasola­biale continuous with upper lip
- no philtrum
 
horse
- small cartilage laterally
- extra alar cartilage supports dorsal, ventral, medial
- nothing laterally → nostrils can stretch
- horse must breath by nose
- normal skin around nostrils

nose - EXTERNAL NOSE

provide moisture for nose
in ruminant and pig - glands in planum
in carnivores (no gland in planum)
- lateral nasal glands
- glands in septum
- lachrymal glands

NASAL CAVITY

nasal septum
perpen­dicular plate
- caudal
- continuous with cribriform plate (both ethmoid bone)
cartil­aginous nasal septum
- rostral
- supported by vomer
have nasal conchae (turbinate bones)
- thin complex, bony scrolls projecting from inside of lateral wall
- types: dorsal, (middle), ventral, ethmoidal

nasal cavity - NASAL CONCHAE

dorsal nasal concha
- enlong­ated, sightly curled scroll
ventral nasal concha
- tightly folded series of scrolls
- more extensive than dorsal nasal concha
 
mucosal folds
- rostral to conchae
- straight fold is rostral extension of dorsal concha
- alar fold is rostral extension of ventral concha
bulbous enlarg­ement - divert air and increase evapor­ation
supported by alar cartilage in horse
 
ethmoidal conchae
- series of folding plates
- caudal part of nasal cavity
- linked with ethmoid bone
- extend up into frontal sinuses

nasal cavity - NASAL MEATUSES

spaces between roof and floor nasal cavity, and dorsal and ventral conchae
3 meatuses
- dorsal nasal meatus
- middle nasal meatus
- ventral nasal meatus
in horse, common meatus between conchae and septum

nasal cavity - ASSOCIATED STRUCTURES

INCISIVE DUCTS (nasop­alatine duct)
- paired
- connect oral and nasal cavities
- nasal opening - floor nasal cavity at canine level
- oral opening - incisive papilla - caudal to upper central incisors
 
VOMERO­NASAL ORGAN
- paired blind sacs run caudally from incisive ducts to level P 2-4
- cartilage support
function of ducts
- epithelium both respir­atory and olfactory
- pheromones and flehmen
- taste and smell
 
LATERAL NASAL GLAND
- serous gland, micros­copic (not exist in ox)
- near nasoma­xillary opening; duct opens into middle meatus near end straight fold
- humidify inhaled air; may aid function for vomero­nasal organ
- humidify nose
- thermo­reg­ulatory support
 
NASOLA­CRIMAL DUCT
- from medial canthus eye into nasal cavity
- drains eye to prevent weeping; humidify nose and nasal cavity
- often blocked brachi­oce­phalic breeds
in horse - no oral opening

nose - PARANASAL SINUSES

GENERAL CHARAC­TER­ISTICS
- air-filled spaces inside bones connected to nasal cavity
- lined by mucope­rio­steum
- named after bones where they lie
 
FUNCTIONS
- lighten skull
- insulate nervous centers
- protect eyes, nasal passages and cranial cavity
- absorb shock
- amplify voice
- increase area olfactory membrane
 
CLASSI­FIC­ATION
- all species: frontal and maxillary sinuses
- vary in size, shape and other sinuses
- openings into nasal cavity narrow
→ blocked by mucosal swelling
→ prevent drainage

paranasal sinuses

MAXILLARY SINUS
- largest
- commun­icate with middle meatus via nasoma­xillary opening
- some species have divert­icula into
• hard palate – palatine sinus
• sphenoid bone – sphenoid sinus
• medial aspect orbit – lacrimal sinus
• nasal conchae – conchal sinus
 
FRONTAL SINUS
- opens into ethmoidal meatus (horse - opens into caudal maxillary sinus)

paranasal sinuses - SPECIES

conducting component - NASAL CAVITY - microa­natomy

both 2 regions have different mucosae
RESPIR­ATORY REGION
- paranasal sinuses
- part of dorsal, all ventral conchae
- lateral, dorsal, ventral nasal wall and part of septum
OLFACTORY REGION
- ethmot­urb­inates
- part of dorsal conchae
- part of nasal septum
- vomero­nasal organ

nasal cavity - RESPIR­ATORY MUCOSA

EPITHELIUM
- ciliated pseudo­str­atified columnar with goblet cells
- in paranasal sinuses - more cuboidal to squamous, less glands and goblet cells
LAMINA PROPRIA and SUBMUCOSA
- loose connective tissue blends with perios­teum, perich­ondrium
- leukocytes (eosin­ophils and lympho­cytes)
- simple branched tubulo­acinar mixed nasal glands (less in sinuses)
- erectile venous plexuses with sphincters

nasal cavity - OLFACTORY MUCOSA

EPITHELIUM
- yellowish pigmen­tation
- 3 cell types
sensory (olfac­tory) cells - bipolar neurons, thickness, long, non-motile cilia
susten­tacular (suppo­rting) cells - slender, many microvilli (no cilia)
basal cells - spherical

nasal cavity - FUNCTIONS

olfactory
respir­atory
- filter (dust, bacteria)
- adjust temper­ature and humidity

conducting component - NASOPH­ARYNX

- air from nasal cavity to nasoph­arynx via choanae (internal nares)
- choanae separated by vomer and dorsal to palatine bone (hard palate)
- connected to middle ear by audiotory (Eusta­chian) tube
cartil­aginous through open ventrally
keep middle air at surrou­nding pressure
horse: massive paired evagin­ation ventrally, the gutteral pouches

conducting component - LARYNX

- short muscul­o-c­art­ila­ginous tube (a bunch of articu­lating cartilages held together by muscles, ligaments and membranes)
- connects nasoph­arynx with trachea
- supported by hyoid apparatus

larynx - HYOID APPARATUS

pair bones
- thyrohyoid bone (artic­ulate with thyroid cartilage)
- basihyoid (unpaired, lie transv­ersely)
- kerato­hyoid bone
- epihyoid bone
- stylohyoid bone
- tympan­ohyoid cartilage

larynx - FUNCTION

respir­ation
- maintain air pathway
- regulate airflow to lungs
deglut­ition
- prevent aspiration of food, saliva, etc.
support olfaction - direct air through nasal passage
intrat­horacic pressure regulation - act as a valve
phonation - vocal folds

larynx - CARTILAGES

many articu­lating cartilages with ligaments and muscles
4 main cartilages and 1 minor
- epiglottis (elastic cartilage)
- thyroid (hyaline cartilage, 2 lamina and central body, open dorsally)
- cricoid (hyaline cartilage, complete ring)
- arytenoids (paired, hyaline cartilage)
muscular process - lateral, crest shaped
cuneiform process - elastic cartilage, part of epiglottis in horse, absent pig and ruminants (= wedge shaped)
cornic­ulate process - elastic cartilage, horn shaped, dorsal
vocal process - attachment vocal ligaments
- intera­ryt­enoid (hyaline cartilage, carnivores and pigs)

larynx - ARTICU­LATIONS

3 articu­lations
- cricot­hyroid - simple rotation around transverse axis
- cricoa­ryt­enoid
• rotation around transverse and sagittal axes
• slide to bring arytenoids closer or further
- thyrohyoid - simple transverse axis

larynx - LIGAMENTS

7 ligaments (intrinsic and extrinsic)
- cricot­hyroid
- cricot­racheal
- vocal
- transverse arytenoid
- thyroe­pig­lottic
- hyoepi­glottic
- vestibular

larynx - WALL OF THE LARYNX

PAIRED MUCOSAL FOLDS
vestibular fold
- from arytenoid to epiglottis
- enclose cuneiform process, vestibular ligament and ventri­cular muscle
- absent in ruminants
vocal fold
- from vocal process of arytenoid to body thyroid
- more medial than vestibular fold and encloses vocal ligament
- glottis have space between them
aryepi­glottic fold
- lateral margin of epiglottis to arytenoid (dog and horse)
- lateral margin of epiglottis to cricoid (cat)
- lies dorsal to arytenoid and cricoid (pig and ruminant)
- forms boundary of laryngeal entrance
 
LATERAL VENTRICLE (SACCULE)
- deep blind-­ending pocket lateral wall larynx
- only in dog, pig, horse
- entrance between vocal and vestibular folds (between split vocal ligament in pig)
 
(MEDIAN VENTRICLE) - pig, horse; base epiglottis
 
LARYNGEAL MUCOSA
- stratified squamous epithelium - rostral to vocal folds
- pseudo­str­atified columnar ciliated epithelium caudally

larynx - ARTICU­LATIONS

4 sections
ADITUS LARYNGIS
- entrance
- aryepi­glotic fold, epiglo­ttis, cornic­ulate process
VESTIBULE
- from aditus to vocal folds
- vestibular folds and lateral ventricle
RIMA GLOTTIDIS
- vocal folds and vocal process
INFRAG­LOTTIC CAVITY
- continuous with trachea

larynx - MUSCLES

INTRINSIC MUSCLES
- control movement of cartilages relative to each other
- close or open glottis by abducting or adducting vocal folds
- all attach to processes of arytenoids and rotate them to tension vocal folds (except for cricot­hyroid muscle)
 
Abductors - open glottis
dorsal cricoa­ryt­enoid muscle
- dorsal cricoid to muscular process of arytenoid
- abduct ventral edge arytenoid, draw vocal fold ventrally
 
Abductors - close glottis
cricot­hyroid muscle
- from lat surface cricoid to lat surface thyroid
- draw thyroid and cricoid closer → tense vocal folds without abduction
lateral cricoa­ryt­enoid muscle
- from lateral rostral border cricoid to muscular process of arytenoid
- draw vent edge arytenoid ventrally and medially, adducting vocal cords
transverse arytenoid muscle
- from muscular process of arytenoid, passes dorsally to other arytenoid
- fine tunes other muscles
thyroa­ryt­enoid muscle
- from epiglottis and thyroid (internal midline) to muscular process arytenoid
- in dog and horse, divided into ventri­cularis rostrally and vocalis caudally
- caudal part associate with vocal ligament to form basis vocal fold
- adduct arytenoids

larynx - MUSCLES

EXTRINSIC MUSCLES
- control movement of larynx relative to whole body
- connect with hyoid bones, pharynx, sternum
 
move larynx rostrally
- thyrohyoid muscle
• origin: hyoid apparatus
• insertion: thyroid cartilage
- hyoepi­glottic muscle
• origin: hyoid apparatus
• insertion: epiglottis
- geniohyoid muscle (with styloh­yoid, mylohyoid, stylop­har­yngeus, palato­pha­ryn­geus)
• not attach directly to larynx
• anchor hyoid apparatus rostrally
- rostral movement - important in swallowing (deglu­tition)
 
move larynx caudally
- **ster­not­hyroid muscle (with sterno­hyoid; omohyoid in horses)
- important in strenuous exercise

larynx - INNERV­ATION

2 nerves, both branches of vagus nerve
cranial laryngeal nerve
- external cranial laryngeal nerve (motor to cricot­hyroid muscle)
- internal cranial laryngeal nerve
caudal laryngeal nerve (recurrent larygeal nerve)
- motor to all intrinsic muscles (except cricot­hyroid)
- different paths in LnR sides
 
damage­/de­gen­erate left recurrent laryngeal nerve
→ left laryngeal paralysis
- problem for dorsal cricoa­ryt­enoid muscle (only abductor)
→ can't abduct left vocal cord during exercise →
→ make noise or 'roaring'
- graded and surgical correction
• ‘tie-back’ operation (prost­hetic larygo­plasty)
• nerve grafting using omohyo­ideus
• lateral ventri­cul­ectomy reduces roaring sound

larynx - BLOOD SUPPLY

2 arteries
cranial thyroid artery
- from common carotid artery
cranial larygeal artery
- either from common carotid artery or external carotid artery

conducting component - TRACHEA

from larynx to principal bronchi
non-co­lla­psible, supported by cartilage
2 parts
cervical
- two third of esophagus (upper part) located dorsal to trachea, one third of esophagus (lower part) shifts to left side caudal
- go along with many nerves and vessels
thoracic
- dorsal to cranial vena cava
- divide into 2 branches to base heart at 4th-6th inter costal space

trachea - STRUCTURE

tracheal cartilages
- hyaline
- C-shape, open dorsally
annular ligaments
- fibro- elastic connec­tions between cartilages
trachealis muscle
- dorsal aspect (gap in rings)
- smooth
- external to ring carniv­ores; internal others

trachea - MICROA­NATOMY

mucosa
- pseudo­str­atified columnar ciliated epithelium with goblet cells
- lamina propria of loose, vascular connective tissue
- longit­udinal folds
submucosa
- seromucous tracheal glands
muscul­o-c­art­ila­ginous layer
adventitia

trachea - ROLE

rigid tube for air passes through (can collapse cause pathology)
flexible and extensible
- flexible cartilage; incomplete cartilage rings
- longit­udinal mucosa fold; elastic tissue in submucosa
trap and remove fine particles

RESPIR­ATORY COMPONENT

lungs
pleura - thin membrane corver lungs and lining thoracic cavity
in thoracic cavity
- thoracic inlet
- thoracic wall
- diaphragm
different to thoracic cage

respir­atory component - PLEURA

serous membrane
- serous layer
• simple squamous epithelium
• thin lamina propria
serous fluid/­exudate
- lubric­ation
lines thoracic cavity, form pleural sacs (R > L)
- come together medially, form mẹdias­tinum
- push medially, bound by connective tissue
- contain trachea, oesoph­agus, heart, vessels, etc.
pleural cavity in each sac
 
lungs bud from trachea, push out into pleura → enveloped by pulmonary visceral pleura
form walls of pleural sacs (parietal pleura)
- costal pleura
- diaphr­agmatic pleura
- medias­tinal pleura
lungs expand to fill pleural cavities
pleural space
- narrow space between visceral pleura and parietal pleura
- contains pleural fluid
visceral pleura - cover lungs
parietal pleura - line pleural cavity

pleura - FUNCTION PLEURAL SPACE AND FLUID

make lungs stick to inside of thoracic cavity
- slight vacuum in pleural space
- inborn surface tension of fluid
seal → avoid thoracic wall movement during lung expansion
lubric­ation for lung movement against inside thoracic wall

pleura - MEDIAS­TINUM

partition
- 2 serous membranes
- connective tissue
contains all thoracic structures (except lungs, caudal vena cava and right phrenic nerve)
3 parts
- cranial medias­tinum (pre-c­ardiac)
- middle medias­tinum (cardiac)
- caudal medias­tinum (post-­car­diac)
 

conducting component - NASAL CAVITY - microa­natomy

both 2 regions have different mucosae
RESPIR­ATORY REGION
- part of dorsal, all ventral conchae

conducting component - NASAL CAVITY - microa­natomy

CLASSI­FIC­ATION