18 - The Larynx Flashcards
Where is the larynx found and what are it’s functions?
- Between the hyoid bone (laryngeal inlet) and the end of the cricoid cartilage at C6
- Ventilation
- Airway protection from food and fluid
- Cough reflex
- Phonation
What are the three divisions of the larynx?
Where are the two synovial joints in the larynx?
- Between the arytenoid cartilage and cricoid
- Between thyroid and cricoid cartilage
Label the different parts of the larynx.
What is a cricothyroidotomy?
- In acute laryngral obstruction, e.g due to tongue swelling or laryngospasm, the cricothyroid membrane can be punctured to get below the vocal areas
- Used when cannot intubate or ventilate and temporary solution to hypoxic damage being caused to brain and tissues
Label the following parts of the larynx.
- Aryepiglottic folds are the upper part of the quadrangular membrane
- Aditus = laryngeal inlet
Where do the vocal ligaments (cords) form from?
What is the structure of the thyroid, cricoid and arytenoid cartilages?
- Thyroid: shield like. two lateral plates that meet in the middle to form a laryngeal prominence
- Cricoid: only complete ring of cartilage. Attached to trachea by cricotracheal membrane
- Artyenoid: sit on posterior cricoid
What is the rima glottis?
- Space between the vocal cord, yellow star on the diagram
- Subglottis is true vocal cords to first tracheal ring
What type of epithelium lines the larynx?
All pseudostratified columnar apart from the true vocal cords that are lined with stratified squamous
Label the following view down the laryngoscope?
Can put down ET tube with small balloon past abducted vocal cords
What procedure might you carry out if someone has a change in voice that becomes hoarse?
What are the functions of the intrinsic laryngeal muscles and what nerve are they supplied by?
- Open glottis and vocal cords in inspiration
- Phonation and cough refelx
- Close cords and glottis when swallowing
All recurrent laryngeal from vagus, apart from cricothyroid that comes from superior laryngeal
What is the only intrinsic muscle of the larynx that abducts the vocal cords, and how does it work?
Posterior cricoarytenoid
Moves the arytenoids position on cricoid to change the aperture (rima glottidis)
How do the vocal cords look when speaking and coughing?
Coughing: inspire and fill lungs with air, adduct cords, contract expiratory muscles, abduct cords
If recurrent laryngeal nerve damage then phonation and cough will be affected
What is the function of the cricothyroid muscle?
It stretches the vocal cords making them taut, allowing high-pitched sounds to be made
Supplied by external branch of superior laryngeal
How does the larynx change during swallowing to protect the airways?
- Tongue pushes the epiglottis down along with aryepiglottic muscles contracting
- Vocal cords (glottis) adduct
- Larynx moves anterior to pull off pharynx and moves upwards as hyoid moves upwards
What is the sensory and motor function of the larynx?
Autonomics delivered via CN X to mucosal glands within the larynx
What happens if there is a lesion to the superior laryngeal nerve?
- Often damage external branch when thyroidectomy as associated with superior thyroid artery
- Cricothyroid will be paralysed so hoarseness or issue making high pitched noises
What is the course of the recurrent laryngeal nerve, and how can it be injured?
- Comes from vagus nerve and associated with thyroid and inferior thyroid arteries
- Sensory to all areas below vocal cords and all motor apart from cricothyroid
- Injury: thyroid surgery, aortic arch aneurysm, cancer of apex of the lung, larynx/oesophagus surgery
How does a recurrent laryngeal nerve palsy present?
- Hoarseness of voice and ineffective cough
- Unilateral lesion then vocal cord in paramedian position on affected side between adduction and abduction
- If bilateral then there is a narrow glottis and this is an emergency as really narrow airway
What are some conditions that affect the larynx and how do they present?
Most present with hoarse voice
- Laryngitis
- Singer’s nodules
What is the innervation of the infrahyoid muscles?
- Branches of C1 to C3 from the cervical plexus
- Move and stabilise the hyoid bone during speaking, swallowing, chewing
What is the prognosis for carcinomas in different parts of the larynx?
Glottis: if caught early good prognosis as minimal lymphatic drainage so less likely to spread
Infra/Supraglottis: drain to neck and paratracheal nodes so poorer prognosis
Which recurrent laryngeal nerve is more at risk of being damaged?
Left as goes under the arch of the aorta and back up a groove between the oesophagus and trachea
What is the presenting symptoms of epiglottitis, what is it caused by and how do you treat it?
- Inflammation of the epiglottis, usually due to H.Influenzae B but rare as Hib vaccine
- Usually in children 2-6, stridor, difficulty breathing, difficulty swallowing so may dribble, high fever, sore throat, sitting up in ‘sniffing’ position
- Do not examine as epiglottis may snap shut, refer to ENT and intubate or do a tracheostomy
What is croup caused by and what are the presenting symptoms?
- Usually viral, parainfluenza virus, affecting larynx and trachea
- Common in 6 months to 3 years
- Barking cough made worse on agitation and at night
- Stridor can also occur when upset and cyanosis
How can we treat croup?
- Can often be dealt with at home by giving single dose corticosteroid, calming them down and sitting them up
- If respiratory distress or stridor at rest can give nebulised oxygen and adrenaline with corticosteroids
Why can a hoarse voice be a red flag?
Could be a sign of laryngeal, lung or thyroid cancer
What is the vallecula?
- Recess between root of the tongue and the epiglottis
- When using laryngoscope can put blade in vallecula and push the tongue foward, lifting the epiglottis making it easier to view vocal cords
