larynx & trachea Flashcards
what are the functions of the respiratory system?
- oxygenate blood & excrete CO2
- olfaction
- phonation
- temperature regulation
- regulation of blood pH
what has the features of the respiratory system evolved to do?
- exclude particle matter
- maximise surface area for gas exchange
- warm & humidify air
what are the functions of the larynx?
- respiration
- deglutition - prevents aspiration of foreign material
- assists olfaction
- regulates intrathoracic pressure
- phonation
bones of the hyoid apparatus?
- thyrohyoid bone
- stylohyoid
- epihyoid bone
- keratohyoid bone
- basihyoid (only unpaired bone)
- tympanohyoid cartilage
which bones of the hyoid apparatus are fused in horse?
epihyoid bone & stylohyoid bone
name the 5 cartilages of the larynx
- epiglottis
- thyroid
- arytenoid
- cricoid
- interarytenoid (minor)
name the cartilage of larynx that is elastic cartilage & forms a spout-like entrance to larynx
epiglottis
name the cartilage of larynx that is hyaline cartilage is broad dorsally & narrow ventrally
cricoid
name the cartilage of larynx that is paired, hyaline cartilage & have several processes
arytenoids
name the processes of the arytenoids
- muscular process: lateral & crest shaped for muscle attachment
- cuneiform process: part of epiglottis in horse, absent in pigs & ruminants
- corniculate process
- vocal process: for vocal ligament attachment
what are the articulations of larynx?
- cricothyroid - simple rotation around transverse axis
- cricoarytenoid - complex rotation around transverse & sagittal axis & can regulate size of laryngeal lumen
- thyrohyoid - simple transverse axis
name the larynx ligaments
- cricothyroid
- cricotracheal
- vocal (thyroid to vocal process of arytenoid)
- vestibular (thyroid to cuneiform process to arytenoid)
name the 3 folds present in the wall of larynx
- vestibular fold - encloses cuneiform process, vestibular ligament & ventricularis muscle, absent in ruminants, from arytenoid to epiglottis
- vocal fold - encloses vocal ligament, from vocal process of arytenoid to body of thyroid, glottis is the space between them
- aryepiglottic fold - forms boundary of laryngeal entrance, from lateral margin of epiglottis to arytenoid in dog & horse & to cricoid in cat (but lies dorsal to arytenoid & cricoid in pig & ruminants)
what is the lateral ventricle in the wall of larynx?
- deep blind-ending pocket in lateral wall
- only present in dog, pig & horse
- entrance lies between vestibular & vocal folds
what is the median ventricle?
- an invagination at the base of epiglottis
- only present in pig & horse
what type of epithelium is the laryngeal mucosa rostral to the vocal folds?
stratified squamous epithelium
what type of epithelium is the laryngeal mucosa caudal to the vocal folds?
pseudostratified columnar ciliated epithelium
what are the 4 sections of the laryngeal cavity?
- auditus laryngis
- entrance to larynx, bounded by aryepiglottic fold, epiglottis & corniculate processes - vestibule
- extends from auditus to vocal folds, bounded by vestibular folds & vocal process of arytenoids - rima glottis
- space bounded by vocal folds & arytenoid vocal processes - infraglottic cavity
- continuous with trachea, caudal to glottis
what do the extrinsic muscles of the larynx control?
movement of whole larynx relative to body & are important for deglutition (connect with hyoid bones, pharynx & sternum)
movements do the intrinsic muscles of the larynx control?
- control movement of the individual cartilages in relation to each other
- close or open glottis by abducting or adducting vocal folds
- all attach to arytenoid processes (except cricothyroid muscle)
name the extrinsic muscles that move larynx rostrally for deglutition
- throhyoid (O = hyoid apparatus, I = thyroid)
- hyoepiglottic muscle (O = hyoid apparatus, I = epiglottis)
- geniohyoid muscle (not attached directly to larynx, anchors hyoid apparatus)
name the extrinsic muscle that moves larynx caudally and what it’s important for?
- sternothyroid muscle (with sternohyoid & omohyoid in horses)
- important during strenuous exercise
name the abductor muscle of the larynx
dorsal cricoarytenoid muscle
- O = dorsal cricoid, I = muscular process of arytenoid
- abducts ventral edge of arytenoid, drawing vocal cords laterally
name the adductor muscles of the larynx that close glottis
- cricothryoid m
- lateral cricoarytenoid m
- transverse arytenoid m
- thyroarytenoid m
function of cricothyroid muscle of larynx
- draws thyroid & cricoid closer together to tense vocal folds
- O = lateral surface of cricoid, I = arytenoid muscular process
functions of lateral cricoarytenoid muscle
- draws ventral edge of arytenoid ventrally & medially, adducting vocal folds
- O = lateral border of cricoid, I = arytenoid muscular process
function of transverse arytenoid muscle of larynx
- fine tunes actions of other muscles
- O = arytenoid muscular process, I = other arytenoid processes
function of the thyroarytenoid muscle of larynx
- adducts arytenoids & associated w vocal ligament to form vocal fold
- O = epiglottis & internal midline of thyroid, I = arytenoid muscular process
- dogs & horse = muscle is divided into ventricularis rostrally & vocalists caudally
name the 2 nerves that are branches of the vagus which innervate the larynx
- cranial laryngeal
- recurrent laryngeal
what parts of the larynx is innervated by cranial laryngeal nerve?
- external cranial laryngeal n = motor to cricothryoid muscle
- internal cranial laryngeal n = sensory to laryngeal mucosa
which nerve innervates the cricothryoid muscle (adductor) of larynx?
internal cranial laryngeal nerve
what muscles of larynx does the recurrent laryngeal nerve innervate?
innervates all intrinsic muscles of larynx (except cricothyroid m)
- dorsal cricoarytenoid m
- lateral cricoarytenoid m
- transverse arytenoid m
- thyroarytenoid m
what is the path of the left recurrent laryngeal nerve?
left recurrent laryngeal travels around aortic arch & continues up ventrolateral trachea
what is the path of the right recurrent laryngeal nerve?
right recurrent laryngeal travels around the right subclavian artery & continues up dorsal trachea
what is left recurrent laryngeal hemiplegia & what can it cause?
- is damage of left recurrent laryngeal nerve
- causes paralysis of left side of larynx
- roarers in horses because cricoarytenoid cannot adduct vocal fold during exercise
what is the position of the cervical trachea?
- oesophagus is dorsal to trachea for rostral 2/3, then lies left of trachea in causal 1/3 of neck
what is the position of the thoracic trachea?
- dorsal to cranial vena cava
- bifurcates dorsal to base of heart & at the level of the 4th-6th intercostal space
list the 3 elements in the structure of the trachea
- tracheal cartilages (hyaline cartilage) - C-shaped & incomplete dorsally
- annular ligaments - join tracheal rings together
- trachealis m - on dorsal aspect of tracheal rings & completes gaps in rings
what is the position of the trachealis muscle in carnivores?
lies external to tracheal cartilage rings in carnivores
what is the position of the trachealis muscle in all other species except carnivore?
lies internal to tracheal cartilage rings in other species
what type of epithelium lines the mucosa of the trachea?
respiratory epithelium - pseudostratified columnar ciliated epithelium with goblet
- lamina propria of loose, vascular connective tissue
name the glands present in the submucosa of the trachea
submucosa contains sermomucous tracheal glands
what are the roles of the trachea?
- rigid tube for passage of air
- capable of expansion to accomodate an increase in volume of air passing to & from lungs
- traps & removes fine particles in tracheal mucosa which is removed by muco-ciliary elevator
- flexible & extensible to allow movement of head, neck & larynx
how is the trachea achieve the ability to expand?
- made of flexible hyaline cartilage
- cartilage rings are incomplete
- longitudinally folded mucous membrane
- elastic tissue in submucosa
