Anatomy Of The Larynx Flashcards
Functions of the larynx
- Ventilation
- Airway protection: prevents flood/fluids entering airways
- Cough reflex: rapidly expel anything inadvertently entering airways
- role in sound production (not a primary function)
When does the larynx begin and end?
- begins at laryngeal inlet
- ends at cricoid cartilage C6
What part of the pharynx is posterior to the larynx?
Laryngopharynx
What are the piriform fossae?
A small recess on either side of side of laryngeal inlet
Anatomical relationship between the larynx + the hyoid
Larynx is suspended from the hyoid bone by the thyrohyoid membrane
What connects the cricoid cartilage to the thyroid cartilage?
Cricothyroid membrane
What are the arytenoid cartilages?
Location
Sit on the posterior portion of the cricoid cartilage
What is a cricothyroidotomy?
Example of why you may need it
Incision made through skin + cricothyroid membrane below the vocal cords to provide airway to patient in an emergency
e.g. severe swelling of vocal cords
What are the margins of the laryngeal inlet
2 aryepiglottic folds
Upper edge of epiglottis
What are the aryepiglottic folds?
- Attach epiglottis to arytenoid cartilages
- (The free upper border of the quadrangular membrane)
What is the false vocal cord formed by?
free lower border of the quadrangular membrane
What are the aryepiglottic fold formed from?
free upper border of the quadrangular membrane
What forms the true vocal cords?
Free upper border of cricothyroid membrane
How is the larynx internally divided?
- Supraglottis: epiglottis up to + including false vocal cords
- Glottis: false vocal cords to true vocal cords (narrowest part)
- Infraglottis: below true vocal cord to lower boundary of cricoid C6
What type of epithelium lines the larynx?
What is the exception
- pseudostratified ciliated columnar epithelium (respiratory epithelium)
- true vocal cords > stratified squamous epithelium
What type of epithelium lines the true vocal cords?
Stratified squamous epithelium
What two ways can you view the larynx?
Flexible nasendoscopy
Intubation
What must be viewed for laryngoscopic view during intubation?
- Vocal cords must be viewed
- Placement of endotracheal tube into infraglottic region
Another name for false vocal chords
Vestibular fold
Another name for the true vocal chords
Vocal folds
What is the rima glottidis?
Opening between the true vocal chords
How to orientate yourself when looking at the larynx
Point of rima glottidis points forwards (towards epiglottis)
Functions of the intrinsic laryngeal muscles
- alter size + shape of laryngeal inlet
- alter tension in + position of true vocal chords
How do the intrinsic laryngeal muscles alter the size + shape of laryngeal inlet?
Muscles within aryepiglottic folds contract narrowing inlet + flattens epiglottis
How do the intrinsic laryngeal muscles alter the the tension in + position of the true vocal cords?
Muscles act on arytenoid cartilages to vary position of true vocal cords
Innervation of the intrinsic laryngeal muscles
Recurrent laryngeal nerve
(From vagus nerve X)
(Except cricothyroid muscle)
What is the recurrent laryngeal nerve a branch of?
Vagus nerve X
How does the hyoid bone move during swallowing?
What does this do?
- Moved antero-superiorly by suprahyoid muscles
- Moves position of larynx up + off the pharynx
- Food/fluid directed into open pharynx
What positions can the vocal cords be in?
ADducted (closed)
ABducted (open)
What position are the vocal cords in when swallowing?
Firmly ADducted
(closed)
What position are the vocal cords in when breathing?
ABducted
(open)
What position are the vocal cords in during phonation (talking)?
- ADucted
- But expired air can be forced through
- Vocal cords vibrate > sound waves
What does the variation of tension of the vocal cords determine?
Pitch
Tension of true vocal cords in high pitched vs low pitched sounds
high pitched: vocal cords taut
low pitched: vocal cords less taut
Outline the process of coughing
What is the position of the vocal cords when coughing?
- inspire + fill lungs with air
- vocal cords ADduct
- expiratory muscles contract
- intrathoracic pressure builds
- vocal cords suddenly ABducts
- explosive outflow air
What muscle changes the tension of the true vocal cords (therefore pitch)?
Cricothyroid muscle
Action of cricothyroid muscle
- tilts thyroid cartilage forwards of cricoid
- increases tension in vocal cords
- higher pitch made
Innervation of cricothyroid muscle
External branch of superior laryngeal nerve
(Branch of vagus X)
Motor and sensory supply of the recurrent laryngeal nerve
- motor: intrinsic laryngeal muscles
- sensory: infraglottis
Supply of the external branch of superior laryngeal nerve
Motor innervation to cricothyroid muscle
Supply of internal branch of superior laryngeal nerve
Sensory innervation to supraglottis + glottis
Route of left and right recurrent laryngeal nerve
- left: under arch of aorta
- right: under right subclavian artery
What is the paramedian position?
When does it occur?
- Vocal cords held halfway between full ADduction + full ABduction
- paralysed vocal cord
Symptoms of injury to unilateral recurrent laryngeal nerve
Hoarse voice
Weak/ineffective cough
Complication of bilateral recurrent laryngeal nerve injury
- Both vocal cords assume paramedian position
- Narrows rima glottis
- Significant airway obstruction
What is laryngitis?
Inflammation of larynx
Often involves vocal cords
What is croup?
- common childhood infection
- causes barking cough + rasping sound when breathing
A child presents with a barking/seal like cough, what is the most likely diagnosis?
Croup
What is epiglottitis?
Inflammation of the epiglottis + supraglottis
Significant risk to airway
What conditions can affect the larynx?
- laryngitis
- croup
- epiglottis
- laryngeal oedema
- laryngeal nodule
- laryngeal cancer
Sensory innervation to the larynx
- internal branch of superior laryngeal nerve: supraglottis + glottis
- recurrent laryngeal nerve: infraglottis
What type of cartilage is the epiglottis composed of?
Elastic
What is the most common cause of epiglottitis?
Haemophilus influenzae B
What is the valleculae?
The space between the posterior tongue + epiglottis
