Lecture 16 - Applied Anatomy Of The Larynx Flashcards
What are the functions of the larynx?
Ventilation
Airway protection (main function)
Cough reflex
Phonation (production of sound)
Go the last slide and label image 1:
1 = nasopharynx
2 = oropharynx
3 = soft palate
4 = Laryngopharynx
5 = trachea
Where does the larynx begin?
Where does the larynx end?
Start = where laryngeal inlet communicates with Laryngopharynx
Ends = at C6 vertebral level at cricoid cartilage
What are the piriform fossa?
The point in pharynx where food particles can get stuck preventing it from entering the trachea
What bone is the larynx suspended from?
Hyoid Bone
What is the membrane between the hyoid bone that attaches to the thyroid cartilage?
Thyrohyoid membrane
What is the cartilage that attaches inferiorly to the thyroid cartilage?
Cricoid cartilage
What si the name of the name of the membrane connecting the thyroid cartilage to the cricoid cartilage?
Cricothyroid cartilage
What is the name of the membrane joining the cricoid cartilage to the trachea?
Cricotracheal membrane
What is the order of structures from the hyoid bone inferiorly?
Hyoid bone
Thyrohoid membrane
Thyroid cartilage
Cricothyroid membrane
Cricoid cartilage
Cricotracheal membrane
What special cartilages sit superiorly on the cricoid cartilage?
Arytenoid cartilages
How can you palpate/determine where the Cricothyroid membrane is?
Palpate the Adam’s apple (laryngeal prominence of the Thyroid cartilage)
Its the soft and squishy area immediately inferior to it
Why may you need to rapidly identify the Cricothyroid membrane?
For front of neck access for a Cricothyroidotomy
What is a cricothryoidotomy?
Where a hole is made in the Cricothyroid membrane for emergency access to the airways underneath the vocal cords
What cartilage does the epiglottis connect to?
Throid cartilage
What i the joint called between the cricoid cartilage and the arytenoid cartilage called?
Cricoid-arytenoid cartilage
What is the synovial joint which allows the thyroid cartilage to tilt forwards?
Thyroid-Cricothyroid joint
What structure does the true vocal cord run from and to?
Runs from arytenoid cartilage to the inner surface of the thyroid cartilage
What is the laryngeal inlet?
The start of the larynx
What forms the margins of the laryngeal inlet?
The 2 aryepiglottic folds either side and the upper edge of the epiglottis
What structures does the quadrangular membrane form?
Aryepiglottic fold
False vocal cord/vestibular fold
What border of the quadrangular ligament forms the aryepiglottic fold?
Upper border
What border of the quadrangular ligament forms the vestibular ligament/false vocal cord?
Lower border
The upper border of what membrane forms the true vocal cord?
What cartilage does this have an edge running deep to?
Cricothyroid membrane
Thyroid cartilage
What type of eof membrane lines the larynx?
Mucous membrane
What are the 3 named regions of the larynx?
Supraglottis
Glottis
Infraglottis
What is the Supraglottis of the larynx?
Most superior section
From epiglottis to the false vocal cords/vestibular ligament
What is the glottis of the larynx?
The narrowest part
Where the true vocal cords can be found
Between false cords and 1cm below true cords
What is the Infraglottis of the larynx?
Below the glottis to lower boundary of the cricoid cartilage
Go to the last slide and label image 2:
(Larynx)
1 = Supraglottis
2 = glottis
3 = Infraglottis
4 = false cords/vestibular ligament
5 = true vocal cords
6 = epiglottis
What type of epithelium lines most of hte larynx?
Pseudostratified Ciliated columnar epithelium
(Respiratory epithelium)
Which part of the larynx is NOT line by Pseudostratified Ciliated columnar epithelium?
True vocal cords
What cells line the true vocal cords?
Why?
Stratified squamous epithelium
Exposed to lots of abrasive forces from the air
How can we visualise the larynx?
Flexible nasendoscopy
Endotracheal tube during intubation
What is the name of the depression anterior to the epiglottis in the larynx?
Valecula
What is the name of the depressions/fossae towards the posterior wall of the Laryngopharynx?
Piriform fossae
Go to the last slide and label image 3:
1 = valecula
2 =aryepiglottic folds
3 = false vocal cords/vestibular folds
4 = true vocal cords
5 = arytenoid cartilage location
6 = Piriform fossae
7 = Rima glottidis
What is the rima glottidis?
The opening between the true vocal cords
How can you determine anatomical position from the rima glottidis?
The point of the rima glottidis points anterior
Broadly what can we do to the larynx to prevent food entering the trachea during swallowing?
Alter shape and position of larynx in swallowing
What are the 2 main functions of the intrinsic laryngeal muscles?
Alter size and shape of laryngeal inlet
Alter tension and position of the true vocal cords
What do the intrinsic laryngeal muscles act on to vary the position of the true vocal cords to control pitch of voice/tension in cords?
Arytenoid cartilages
Where are the intrinsic laryngeal muscles which contract narrowing the laryngeal inlet and flattening the epiglottis?
Aryepiglottic folds
What nerves supply the majority of the intrinsic laryngeal muscles?
What cranial nerve is this a branch of?
Recurrent laryngeal nerves
Branch from the Vagus Nerve (X)
During swallowing, how does the larynx act to protect the airways from food and fluid?
Epiglottis flattens
Aryepiglottic folds contract narrowing laryngeal inlet
Food caught in the piriform fossae
What bone moving is important in protecting the airways in swallowing?
Hyoid Bone
What muscles move the hyoid bone during swallowing?
What muscle stabilises the hyoid bone?
Suprahyoid muscles
Infrahyoids
How do the suprahyoid muscels move the hyoid bone?
Move antero-superiorly
How does movement of the hyoid bone Antero-superiorly by the suprahyoid muscles help protect the airway from food and fluid?
Hyoid moves the larynx up and off the pharynx this directs any food/fluid collected in the piriform fossa into the open pharynx
The movement of what cartilage opens and closes the true vocal cords/rima glottidis?
Arytenoid cartilage
What action would a person be doing if their true vocal cords were firmly adducted and the laryngeal inlet narrowed?
Swallowing
(Protecting the trachea)
What action would a person be doing if their true vocal cords were abducted and the laryngeal inlet open?
Breathing/ventilating
What is the position of the true vocal cords during phonation/speech?
How does this produce speech?
They are closely adducted but expired air can be forced through
Vocal cords vibrate along their length setting up vibrations int he air
What happens to the vocal cords in the cough reflex?
Inspired and fill lungs with air
Vocal cords ADduct
Expiraotry muscles contract
Intra thoracic pressure increases
Vocal cords then suddenly ABduct allowing explosive outflow of air
What muscles control the pitch of the voice/tension in the Vocal cords?
Cricothyroid muscles
How do the Cricothyroid muscels control pitch of the voice?
Controls the tilt of the thyroid cartilage on the cricoid cartilage controlling how taut it is
Vocal cords taut = high pitch
Vocal cords less taut = low pitch
What nerve innervates the Cricothyroid muscles therefore controlling pitch?
What is this a branch of?
External branch of superior laryngeal nerve
Branch of the Vagus nerve (X)
What artery is the external branch of teh superior laryngeal nerve associated with?
Superior thyroid artery
What can happen if the external branch of the superior laryngeal nerve is damaged in a thyroid surgery?
Hoarseness of voice when trying for higher pitched sounds
What are the 2 main nerves branching from the vagus nerve supplying the larynx?
Superior laryngeal nerve
Recurrent laryngeal nerve
What are the 2 branches from the superior laryngeal nerve?
Internal branch
External branch
What is the function of the internal branch of the superior laryngeal nerev?
Sensation to Supraglottis and glottis (+true vocal cords)
What is the function of the external branch of the superior laryngeal nerve?
Motor function to Cricothyroid muscles (control pitch of voice)
What is the function of the recurrent laryngeal nerve?
Motor function to intrinsic laryngeal muscles (moving vocal cords)
Sensory to Infraglottis
What is the route of the left recurrent laryngeal nerve?
Branches from the left vagus nerve and loops under the arch of aorta to where it then ascends upwards to the larynx
What is the route of the right recurrent laryngeal nerve?
Branches from right vagus nerve
It then loops under the right subclavian artery to where it then ascends up to the larynx
What type of surgery puts the external laryngeal nerve at risk?
Thyroid surgery since it runs closely with the superior thyroid artery
What does injury to the recurrent laryngeal nerve cause?
Vocal cord palsy (needed to move the true vocal cords)
How does a unilateral recurrent laryngeal nerve. Injury present?
Hoarse voice
Weak/ineffective cough
Cant fully abduct or Adduction cords
If the right recurrent laryngeal nerve is damaged what would the position of the right vocal cord be?
Halfway between adducted and abducted
(PARAMEDIAN position)
Why is a bilateral recurrent laryngeal nerve injury life threatening?
Both vocal cords assume resign gparamedian position so rima glottis NARROW
Significant airway obstruction
Need emergency surgical airway access below Vocal cords
Cricothryoidotomy
What is laryngitis?
Inflammation of larynx often involving vocal cords
Why do you often lose your voice with laryngitis?
Cant create a full seal of the vocal cords due to the inflammation
How dangerous is epiglottis?
Very dangerous since significant risk to airway
What causes laryngeal oedema?
Allergic reaction or swallowed foreign body
What is a laryngeal nodule?
Benign lump in larynx
What type of tumour are laryngeal cancers normally?
Squamous cell carcinoma on vocal cord
What is Croup?
Viral infection of subglottic region and laryngeal mucosa causing inflammation oedema
Who does croup usually affect?
Young children/infants
What is epiglottitis?
Inflammation/infection of the supraglottis
What are the 3 most likely causative pathogens for epiglottitis?
Haemophilus influenzae B
Streptococcus pneumoniae
Moraxella catarrhalis
Go to the last slide and label the larynx:
(4)
1 = epiglottis
2 = laryngeal inlet
3 = false vocal cord
4 = true vocal cord
5 = infraglottis/subglottic region
6 = trachea
7 = aryepiglottic fold
8 = hyoid bone
9 = thyroid cartilage
10 = cricoid cartilage
11= lateral lobe of thyroid gland
What is the afferent and efferent limb of the gag reflex?
Afferent = Glossopharyngeal
Efferent = vagus
What structure does the left recurrent laryngeal nerve runn close to?
Superior thyroid artery
What symptoms occur if the external branch of superior laryngeal nerve is injured and why?
Hoarseness with high pitch
Innervates the cricothyroid muscles which control tone of vocal cords (angle of thyroid cartilage on cricoid cartilage)
What are a couple causes of voice hoarseness?
Laryngeal cancers
Pancoast tumours
