10 Flashcards
(30 cards)
What are the 4 main functions of the larynx
- airway protection: preventing food/fluid etc. Entering airways
- ventilation: movement of air in/out of lungs
- important role in cough reflex: rapidly expel anything inadvertently entering airway
- role of production in sound: phonation
What structures is the larynx located between?
- hyoid bone above
- trachea below
- C4 to C6
Where does larynx begin and end?
- begins at laryngeal inlet
- ends at lower border of cricoid cartilage (C6)
- continues as trachea
- see session 10 anatomy slide 5
What are the 3 internal subdivisions of the larynx?
- supraglottis: aka vestibule and includes the false vocal cords
- glottis: between the true vocal cords
- infraglottis: between the true vocal cords and the first tracheal ring
- where the mucosal folds internally divide
See session 10 anatomy slide 13
Describe the framework of the larynx (cartilages, membranes and ligaments)
- epiglottis: elastic, leaf-shaped, moves like a trap door
- arytenoid cartilages: pyramid-shaped
- cricoid cartilage: complete signet ring
- synovial joint between the arytenoid cartilages
- synovial joint between thyroid cartilage and cricoid cartilage
- thyrohyoid membrane which suspends thyroid cartilage from hyoid bone
- cricothyroid membrane which is palpable, runs upwards from cricoid cartilage but deep to thyroid cartilage giving it a free upper margin which is thickened and forms the vocal ligament
- laryngeal prominence: Adam’s apple
See session 10 anatomy slide 7-9
What is a cricothyroidotomy?
- provides emergency access to airway, beneath vocal cords
- used during acute laryngeal obstruction (ex. Due to tongue swelling)
- can be punctured enabling a patient to breath as it gives rapid access to the infraglottic area of larynx
- temporary solution until more definitive airway can be established
- used in “cant intubate, can’t ventilate”
See session 10 anatomy slide 10
How are the laryngeal inlet and aryepiglottic folds formed?
- sides of epiglottis are connected to arytenoid by aryepiglottic folds
- quadrangular memberane joins the sides of the epiglottis to the arytenoid giving the shape to these folds
- they form the margins of the entrance
See session 10 anatomy of slide 11
How are the vocal cords formed?
- inferior border of aryepiglottic membrane and superior border of cricothyroid membrane give rise to vocal folds
- free lower border of quadrangular membrane known as vestibular ligament (fixed): false vocal cord
- free upper border of cricothyroid membrane known as vocal ligament (mobile): true vocal cord
See session 10 anatomy slide 12
What is the rims glottidis?
-space in the middle between the true vocal cords
What type of epithelium lines the larynx?
- pseudostratified ciliated columnar epithelium since it Lis part of the respiratory tract
- exception: true vocal cords that are lined with stratified squamous
Describe a laryngoscopic view and intubation
- use a laryngoscopes to view the larynx
- intubation requires an endotracheal tube to be passed through pt’s oral cavity, upper pharynx, into larynx and through vocal cords so that it sits in upper part of trachea
- ET tube has a small ballon at the end which is inflated to ensure the tribe remains securely in place
- ET tube has a lumen which allows for mechanical ventilation and oxygenation of pt’s lungs
- vocal cords will be in a relatively abducted position in preparation for intubation
See session 10 anatomy slide 15-16
What are the functions of the intrinsic laryngeal muscles?
Two main actions
- alter size/shape of laryngeal inlet
- alter tension/position of vocal cords
Swallowing
- close laryngeal inlet and vocal cords
- protect resp tract
Inspiration/expiration
- open vocal cords (and laryngeal inlet)
- allowing movement of air
Phonation and cough reflex
-vocal cords
All innervated by recurrent laryngeal nerve
See session 10 anatomy slide 17
Which intrinsic muscle of the larynx is the only one that abducts the vocal cords?
Posterior cricoarytenoid
See session 10 anatomy slide 18
Which intrinsic muscle is the only one found outside the larynx? What is its function?
- cricothyroid muscle
- function in tensing and slightly adducting the true vocal cords
- does this through tilting the thyroid cartilage on the cricoid cartilage
- by tensing the true vocal cords, higher pitched sounds can be made
- cricothyroid is supplied by external laryngeal nerve which is a branch of the superior laryngeal nerve
See session 10 anatomy of slide 25
What do majority of the intrinsic muscles do?
- these act to move the arytenoid cartilage at the cricoarytenoid joint thus allowing opening and closing of the rima glottidis by abducting and adducting the true vocal cords (the majority adduct the true vocal cords either directly or indirectly).
- These movements are important in allowing the passage of air in and out of the lungs, phonation and in protecting the airway during swallowing
See session 10 anatomy slide 19
What are the vocal cord movements?
Inspiration and expiration
-vocal cord abduct
Phonation
- vocal cord adduct
- expired air forced through closely adducted vocal cords
- vocal cord vibration creates sound waves
See session 10 anatomy slide 20
What happens in the vocal cords during coughing?
- inspire and fill lungs with air
- vocal cords then ADDUCTE
- expiratory muscles contract
- intrathoracic pressure builds
- then cords suddenly ABDUCTED
- explosive outflow of air
- both vocal cords have to meet in midline (adduct) to allow for phonation and cough
See session 10 anatomy slide 21
How is pitch of sound determined by vocal cord tension?
- high-pitched sounds: vocal cords taut
- low-pitched sounds: vocal cords less taut
See session 10 anatomy slide 22
How does the larynx protect the airway during swallowing?
- some intrinsic muscles attach to epiglottis and their contraction pulls down the sides of epiglottis to cover over the laryngeal inlet
- hyoid bone elevated and moved anteriorly by suprahyoid muscles so that it causes the larynx to move up and forward
- tongue pushes epiglottis posteriorly and aryepiglottic muscles contract
- closure of vocal cords (glottis)
See session 10 anatomy slide 27-28
Describe vagus innervation to the larynx
- provides sensory innervation to larynx
- internal laryngeal nerve (branch of superior laryngeal): innervates laryngeal mucosa above the vocal cords and glottis, purely sensory
- recurrent laryngeal nerve: innervates mucosa below the vocal cords
- external: motor to cricothyroid,
See session 10 anatomy of slide 29-30
Why must we be careful of the laryngeal nerves during a thyroidectomy?
- superior and recurrent laryngeal nerves are accompanied by the superior and inferior thyroid arteries
- must be careful so that we can avid a vocal cord paralysis
See session 10 anatomy slide 31
In what ways can the recurrent laryngeal nerve be injured?
- it’s close to inferior thyroid artery so can be injured during thyroid surgery
- aortic arch aneurysm (left RLN)
- cancer involving apex of lung (right RLN)
- left apical lung tumours
- carcinomas of larynx which will present with hoarseness of voice
- disease or surgery involving larynx, Oesophagus or thyroid
- have long courses in the neck (especially left) where it loops under aortic arch b/n oesophagus and trachea so it is susceptible to injury and disease
See session 10 anatomy slide 32
What is a unilateral RLN injury?
- causes the vocal cord on the AFFected side to become immodbil and take up a neutral position between abduction and adduction
- since opposite side is unaffected, it can compensate quite well
- however there may be some hoarseness and weaker cough
- passage of air through glottis is hardly affected so there is no difficulty with breathing
What is a bilateral RLM injury?
- both vocal cords assume the paramedialn position
- rima glottidis is very narrow
- affects pt’s ability to speak and also obstructs movement of air into and out of trachea
- pt’s develop difficulty breathings
See session 10 anatomy slide 33-34
