Flashcards in H&N 11.1 The larynx Deck (48):
What are the main functions of the larynx?
-air conduction for respiration
What is the epiglottis?
a leaf shaped cartilaginous structure which changes position to close of the larynx when food passes.
What are the 2 surfaces of the epiglottis?
-the lingual surface-covered in stratified squamous epithelium
-The under side which is covered in respiratory epithelium.
What are the connections of the epiglottis?
-thyroepiglottic ligament connects the glottis to the thryoid cartilage anteriorly
-hyoepiglottis ligament- connects to the hyoid bone anteriorly.
How does the epiglottis close?
Elevation of the hyoid bone during swallowing (due to suprahyoid muscles, pharyngeal muscles etc) causes the flap of the epiglottis to close- moving from a verticle to a horizontal position.
The upper third of the epiglottis then moves below horizontally, to cover the laryngeal inlet.
During swallowing, what is the aim of pulling down the epiglottis?
-prevents aspiration of food
-directs food into piriform fossae
what is the clinical relevance of the piriform fhossae?
They are a common site for things to get stuck (particulalry sharp things)
Damage here leads to the feeling of something being lodged in larynx.
What symptoms would epiglottitis cause?
What are the main cartilages of the larynx?
Give some features of the thyroid cartilage.
It is the largest cartilage in the larynx.
It is an incomplete ring, it doesn't cover the posterior larynx
It has superior and infeiror horns for articulation with the hyoid superiorly, and the cricoid inferiorly.
The voice box is found within the thyroid cartilage.
consists of 2 lamina connected in the middle via the laryngeal prominence.
Give some features of the arytenoid cartilages.
They are found between the tyroid and cricoid cartilages.
They rotate on the cricoid to control tension, length and position of the vocal cords, therefore producing sound.
What anatomical structures attach to the thyroid cartilage?
Give some features of the cricoid cartilage.
It's the only full ring of cartilage found within the larynx
larger posteriorly (signet ring shaped)
It is fixed to the trachea (via criotracheal ligament)
It articulates with the thyroid cartilage and the arytenoid cartilages.
Clinically, how can you make use of the full ring of the cricoid cartilage?
If someone needs emergency surgery (no preparation) you can press on the anterior cartilage when they've been put to sleep, and this will compress the posterior aspect against the oesophagus, preventing reflux of oesophageal contents, and therefore aspiration.
Name the important membranes of the larynx.
What is the significance of the membranes of the larynx?
They form the vestibular and the vocal cords, therefore are responsible for speach.
Name the important ligaments of the larynx.
-median cricothyroid ligament
What is another name for the quadrangular membrane?
Where would you insert a tracheostomy?
Just below the thyroid and cricoid cartilages, by piercing the cricothyroid ligament.
When looking at a view from a laryngoscope, how do you orientate yourself?
-the epiglottis may or may not be visible, if it is, this indicates the anterior side
-The vocal cords come closer together anteriorly.
Where do the vocal folds run from and to?
-from the thyroid cartilage
-To the arytenoid cartilages.
What is the lining of the vocal folds?
Stratified squamous epithelium, non-keratinised.
What are the false vocal cords made of?
The lower border of the quadrangular membrane
What are the true vocal cords made of?
The free upper border of the crico-thyroid membrane.
What is the space between the vocal cords called?
How is the size of the rima Glottidis changed?
By Abducting and adducting the vocal cords,
This is achieved by the actions of the intrinsic laryngeal muscles.
Which muscle is the only muscle to abduct the vocal cords?
Posterior cricoarytenoid muscle
Generally, what nerve innervates the intrinsic laryngeal constrictors?
Recurrent laryngeal nerve (a branch of the vagus)
What is special about the cricothyroid muscle, with regards to other laryngeal constrictors?
It's the only intrinsic laryngeal constrictor to lie outside of the thyroid cartilage.
What is the action of the cricothyroid muscle?
It acts to increase vocal pitch.
What position must the vocal cords be in to breath?
What position must the vocal cords be in to swallow?
Fully adducted (further protection on top of the closure of the epiglottis)
What position must the vocal cords be in to allow for phonation?
How can the larynx be divided up into regions?
supraglottis (from the epiglottis to the vestibular folds)
Glottis (from the vestibular folds, containing the vocal cords, to 1cm below the true vocal cords)
subglottis (down to the lower border of the cricoid)
What is the sensory innervation of the different regions of the larynx?
Supraglottis- internal branch (from the superior laryngeal nerve)
Subglottis- recurrent laryngeal nerve
glottis is a mixture of the 2.
What is the motor innervation of the laryngeal muscles?
All innervated by the recurrent laryngeal nerve except the cricothyroid which is innervated by the external branch of the superior laryngeal nerve.
How does the superior laryngeal nerve enter the larynx?
By piercing the thyrohyoid membrane.
Where does the recurrent laryngeal nerve loop under?
Right- subclavian artery
Left- Arch of aorta
Why are the laryngeal nerves at risk of damage?
Due to their long course, pathology anywhere along that course can affect the nerves.
Which arteries accompany the superior laryngeal nerves?
Superior thyroid artery.
Which arteries accompany the recurrent laryngeal nerves?
Inferior thyroid artery.
What pathologies can cause recurrent laryngeal nerve palsy?
-apical lung tumours
who is most at risk of developping laryngeal cancer?
-people who live in the west
With regards to laryngeal cancer, which type is favourable?
Laryngeal cancer in the supraglottis, it is easier to remove and has a better prognosis.
The lymphatic drainage is minimal here so it is less likely to have spread.
What factors in someones history might lead you towards laryngeal cancer?
-hoarseness of voice
-feeling of a FB in the larynx
-otalgia (due to referred pain of the vagus nerve)
What is the result of a unilateral complete injury of the recurrent laryngeal nerve?
The corresponding vocal cord will assume the paramedian position, somewhere between adducted and abducted.
Breathing will be ok due to compensation of the other vocal cord.
speach may be hoarse, and coughing will be weaker.
What is the result of a bilateral complete injury to the recurrent laryngeal nerves?
both vocal cords will assume the paramedian position,
Rima glotidis will become much narrower, making breathing difficult- may cause stridor
Phonation wont be able to happen