Larynx Flashcards
Where is the location of the larynx?
- Enclosed in the pretracheal fascia of the neck
- in the visceral layer of the pretracheal fascia
- very thin muscular layer lies anterior to the visceral layer
what is the larynx anterior to?
laryngopharynx
what is the larynx between?
carotid sheath structures
what level of the cervical vertebrae is the larynx found?
C4-C6
what does the ;larynx communicate with?
- oropharynx and nasopharynx above
- oral cavity
- nasal cavity
- trachea below
at what vertebral level does the larynx become the trachea?
C6
what is the skeleton of the larynx made of?
composed of cartilages suspended from hyoid bone
what are the functions of the larynx?
-maintaining patency of URT
:cartilages
-help prevent entry of foreign bodies into LRT
:vocal cords and cough reflex
-produce sound
:vocal cords
what is the membrane connecting the hyoid bone and thyroid cartilage?
thyrohyoid membrane
what is the membrane connecting the thyroid cartilage and the cricoid cartilage?
cricothyroid membrane - access point for cricothryoid puncture
what type of cartilage are all the cartilages and what is the exception?
- Hyaline
- Exception : epiglottis is elastic
How many cartilages are there in the larynx?
9
- 3 pairs
- 3 individual
what is the only cartilage that is completely enclosed?
cricoid
what are the 2 horns of the thyroid cartilage?
- superior
- inferior
what is the anterior structure of the thyroid cartilage?
laryngeal prominence
what allows the nodding movement between the thyroid and cricoid cartilages?
the capsule of the right cricothyroid joint (synovial)
what stretches the posterior and slightly lateral side of the cricoid cartilage?
lamina
what is the way into the larynx?
laryngeal inlet
what cartilage is found inside the larynx?
arytenoid cartilages
where do the vocal cords attach between?
- thryoid cartilage
- vocal processes of arytenoid cartilages
what do the anterior and lateral processes of the arytenoid cartilage attach to?
- anterior- vocal cord
- lateral- muscule attaches
what is the space between the vocal cords called?
rima glottidis
what cartilages are located deep to the laryngeal mucosa and what is their function?
- cuneiform and corniculate cartilages
- support the laryngeal inlet but play no part in moving the vocal cords
what is the mucosal lining of the inside of the larynx mainly and whats the exception?
- respiratory epithelium
- exception: the vocal cords - stratified squamous epithelium
what is the mucociliary escalator?
- mucous glands secrete mucous onto the epithelial surface
- cilia beat to sweep the mucous (plus any foreign bodies stuck in the mucous) superiorly, towards the pharynx, to be swallowed
Describe the vocal cords.
False vocal cords:
- superior
- vestibular folds
True vocal cords:
- inferior
- vocal folds
what is the main sensory supply to the laryngeal mucosa?
CN X -vagus
what branch of vagus supplies superior to vocal fold?
internal laryngeal branches of superior laryngeal branch of CN X
what branch of vagus supplies vocal fold and inferior?
recurrent laryngeal branches of CN X
what is the continuation of the recurrent laryngeal nerve that supplies the larynx?
inferior laryngeal nerve
Describe the extrinsic muscles of larynx.
Suprahyoid muscles:
- Elevators of the larynx (and hyoid)
- Also stylopharyngeus
Infrahyoid muscles:
-Depressors of the larynx (and hyoid)
where are the intrinsic muscles of the larynx found?
attach between cartilages
what are the 4 types of intrinsic muscles of the larynx?
- tensors (of the vocal cords)
- relaxers(of the vocal cords)
- adductors (of the vocal cords)
- abductors (of the vocal cords)
what are all the intrinsic muscles of the larynx supplied by?
(somatic) motor branches of the vagus nerves (CNs X)
what muscle tenses the vocal cords?
-cricothryoid muscles -‘nodding’ the thyroid cartilage anteriorly at the cricothyroid joints, stretches vocal cord
what muscle relaxes the vocal cords?
- thyro-arytenoid muscles
- pull the arytenoid cartilages towards the thyroid cartilage
what muscle adducts the vocal cords?
- lateral cricoid-arytenoid muscles
- rotate the arytenoid cartilages so that the vocal processes of the cartilages come together in the midline
what other muscles assist cricoid-arytenoid in adducting the vocal cords?
- arytenoid muscles
- transverse and oblique arytenoids
- sphincter function
what muscle abducts the vocal cords?
- posterior cricoid-arytenoid muscles
- rotate the arytenoid cartilages so that the vocal processes of the cartilages move laterally
- widens the rima glottidis
Describe the shape of the rima glottidis.
a) resting - laryngeal muscles relaxed
b) forced respiration - posterior crico-arytenoids contract
c) Phonation- arytenoids contract and assist lateral cricoid-arytenoids
d) whispering- lateral cricoid - arytenoids contract
How is sound produced in the larynx (phonation)?
- expire a stream of air across vocal cords
- length/tension of vocal cords dictates pitch of sound produced by vibration of the cords
Describe the production of oral sounds.
- soft palate tenses (CN V3) and elevates (CN X) to close off entrance into nasopharynx
- directs stream of air through oral cavity
- sound interrupted by the tongue (CN XII) and the teeth/lips (CN VII) to produce most vowels and consonants in English language
Describe the production of nasal sounds.
- soft palate tenses (CN V3) and descends (CN X) to close off entrance into oropharynx
- directs stream of air through nasal cavities
- produces one of three sounds: “m”, “n” or “ing” depending on position of tongue (CN XII), teeth and lips (CN VII)
How can you clinically test the vagus nerve?
-listen to patient speak:
is voice hoarse?
are the intrinsic muscles of larynx functioning normally to move the vocal cords
-ask patient to swallow small sip of water:
watch larynx move up and down
-ask patient to cough:
is cough normal and powerful?
also requires functioning diaphragm, phrenic nerves, abdominal wall
Describe the anatomy of coughing.
- breathe in using the diaphragm (phrenic nerves)
- close the vocal ligaments (CN X)
- contract the abdominal wall to build up pressure beneath the closed vocal ligaments
- suddenly open the vocal ligaments (CN X)
- tense (CN V3) and raise (CN XI) the soft palate to direct the stream of air through the mouth
what is aspiration?
Inhalation of liquid or solid into the lungs
what are the symptons of a patient with damage to CN X ?
- a hoarse voice
- abnormal swallow
- weak cough
what are emergency airway manangment procedures during laryngeal obstruction?
- Heimlich manoeuvre
- Cricothyroid puncture / tracheostomy
