B26 Flashcards
Larynx blood supply and innervation
General overview of larynx
it is a cartilaginous tube located in ru and eq in the intermandibular space, while in Ca and su it lies closer to the basis of the neurocranium
It is related to laryngopharynx rostrally and the trachea caudally
is serves as a passageway for oxygen into the lungs
it proctects the lungs from feed stuff and liquids by closing the epiglottis
and is a organ of phonation
The cartilages of the larynx
composed of 4 hyalin cartilaginous parts which are connected together
the arythenoid is paired and lies dorsally
the cricoid is situated most caudally andd is connected to the trachea and the thyroid cartilage
the thyroid cartilage forms the ventral and lateral sides
epiglottis is found most rostrally
Thyroid cartilage
has a left and right lamina which meets on the ventral side
on the lateral side of the lamina linea obliqua can be found, this serves as attachment point for muscles (thyropharyngeus)
Two cornu are formed rostrodorsally and caudodorsally, these are the point which articulates whit th thyrohyoid and cricoid cartilage
the pig does not have a rostral horn.
foramen thyroideum is allowing the cranial larygeal nerve and vessels to enter to innervate and supply the mucosa that lines the inside of the laryngeal cavity
The horse has fissura thyrohyoidea whic separates the rostral horn from the rostral lamina, a CT sheeth ill bride it to form a foramen here as well
Other structures
Caudal and rostral (ru) insicura
Arytenoid cartilage
paired
connected to the cricoid and the thyroid and also to each of the arytenoid cartilages (interarytenoid)
It has a process on the internal side for the vocal chord - processus vocalis
processus muscularis - on the alteral side for the attachement of muscles (m.cricoarytenoid)
processus cuneiformis (ca)
processus corniculatis
lig. cricoarytenoid connects the cricoid and arytenoid cartilages
Cricoid cartilage
Ring like structure (arcus cricoideus)
caudally, connects with the first rings of the trachea and rostrally to the thyroid and dorsally to the arytenoid
on the dorsal side crista mediana can be found, serves as attachment point for the cricopharyngeus muscle
Lig. Cricothyreoideum
- From the cricoid cartilage to the thyroid laminae
Lig. Cricotracheale
- The membrane between the cricoid cartilage and the first tracheal ring
Epiglottis
Rostrally situated
closes the opening into the larynx when eating
apex, basis and stalk
the apex is rounded in Ru and su while its sharp in Eq and Ca
basis (stalk=petiolus) connects to the thyroid
fascies lingualis and laryngis
processus cuneiformis in eq
Lig. Thyreoepiglotticum
- Attaches the base of the epiglottis to the thyroid cartilage
Lig. Hyoepiglotticum
- From the basihyoid and keratohyoid bones to the epiglottis
- Su: also from the thyrohyoid bone
Cavum laryngis
Aditus laryngis - the opening between the laryngopharynx and cavum laryngis. bound by the epiglottis, the plica aryepiglottica and the arythenoid cartilages.
Vestibulum laryngis - area between the aditus and vocal folds
Glottis - vocal apparatus, here the vocal folds, rimaglottis (arytenoid cartilages) Divided into two parts:
- Pars intercartilaginea ( between the cartilages)
- Pars intermembranceae ( between vocal folds)
rima glottis - a small passageway leading from the glottis to cavum infraglotticum
Lig. Vocale
From the thyroid cartilage and lig cricothyroideum to processus vocalis
Innervation
Cranial and caudal laryngeal nerves
Lig. vestibulare - false vocal fold, lies laterally to the vocal folds, aids in protecting the trachea from liquids and food
The difference between the intrinsic and extrinsic muscles of the larynx
Extrinsic muscles - moves the entire larynx
Intrinsic muscles - moves the cartialges according to eachother
The muscles of the larynx
Extrinsic
- M. thyrohyoideus
-
M. Hyoepiglotticus
O: basihyoid, keratohyoid or both
I: epiglotical cartilage - M. sternothyroideus
Intrinsic
M. cricothyreoideus
O: Lateral surface of cricoid arch
I: Lateral surface and caudal cornu of thyroid
cartilage
M. cricoarytenoideus dorsalis
O: Cricoid lamina
I: muscular process of arytenoid cartilage
M. arytenoideus transversus
O: muscular process of arytenoid cartilage
I: together with the one from the other side on the median raphe
M. cricoarytenoideus lateralis
O: Internal surfaceof the thyroid lamina, rostroventral portion of cricoid arch
I: muscular process of the arytenoid cartilage
M. thyreoarytenoideus – divided in the horse and dog, uniform in the other animals
Ru + fe
O: base of epiglottis, thyroid cartilage, cricothyroid ligament
I: Muscular process, small fibers on the arythenoid cartilage
Su:
O: Thyroid cartilage
I: muscular process, small fibers on the arythenoid cartilage
M. ventricularis (eq, ca) – rostral
- Together with the vestibule ligament, contained in the vestibular fold
O: thyroid lamina, eq also from cricothyroid ligament
M. vocalis (eq, ca) – caudal
- Inside the vocal fold
O: ventrally from the thyroid cartilage
I: muscular process of the arytenoid cartialge
Innervation of the larynx
N. vagus (X)
- N. laryngea cranialis
- internal - mucosa of the cavum laryngis (x
caudal laryngeal) - external - constrictor of pharynx and
m.cricothyroideus
- internal - mucosa of the cavum laryngis (x
- N.laryngea caudalis (N. laryngea recurrens)
- intrinsic muscles of the larynx (roaring in horse)
Blood supply of the larynx
A. thyroidea rostralis
- r. laryngea
- muscular branch supplying the muscles
- continous into foram thyroideum to supply the laryngea mucosa and vestibular and vocal muscles
