S10 - Larynx Flashcards
What epithelium lines the larynx?
pseudostratified ciliated epithelium (part of the respiratory tract)
What is the main function of the larynx?
To provide a protective sphincter for the lower respiratory tract
Which paired cartilage moves the vocal cords?
Arytenoid cartilages (just on top of the cricoid cartilage)
What is the function of the superior laryngeal nerve?
Internal branch - sensory above the vocal cords
External branch - motor for cricothyroid muscle
It is a branch off of the vagus nerve and pierces through the thyrohyoid membrane
What is the significance of the common carotid bifurcation?
Located at the superior border of the thyroid cartilage.
It is a common site of atheroma
Through which membrane would you perform a cricothyroidotomy?
Cricothyroid membrane - to provide emergency access to airway
Which ligament forms the false vocal cords?
Free lower border of quadrangular membrane - vestibular ligament
From which ligament are the true vocal cords derived from?
Thickened upper border of the cricothyroid ligament
State the anatomical position of the larynx in relation to the laryngopharynx
The larynx is located anteriorly - the epiglottis closes over the laryngeal inlet during swallowing to prevent food in the airway (aided by the soft palate rising)
How are vocal cords kept moist?
Mucous glands located in the small recess (ventricle) located in between the two vocal cords
What are the main actions of the laryngeal muscles?
- change the size and shape of the laryngeal inlet
- move and alter tension of vocal cords in phonation (and cough reflex)
What is the main function of the intrinsic muscles of larynx?
Move vocal cords
Which muscles does the recurrent laryngeal nerve innervate?
Intrinsic muscles of the larynx
- the nerve is a branch off of vagus nerve
Describe the position of the vocal cords during breathing and phonation
Breathing: open (abducted)
Phonation: closed (adducted) - taut if high pitched, relaxed if low pitched
State the importance of the cricothyroid muscle
The only muscle outside of larynx
- bilateral contraction increases length and tension in the vocal cords
(Innervated by the external branch of the superior laryngeal nerve of the vagus nerve)
What is the effect of injuring the superior laryngeal nerve?
Loss of cricothyroid muscle function = hoarseness of voice especially when attempting high pitched sounds
Which muscles elevate the larynx during swallowing?
Suprahyoid muscles and pharyngeal muscles
State the anatomical course of the recurrent laryngeal nerve
Right side: under subclavian artery
Left side: under the arch of the aorta
Up the tracheo-oesophageal groove
Close relationship with the inferior thyroid arteries
Why could a thyroidectomy cause hoarseness of voice?
Cutting the inferior thyroid gland - close relationship with the recurrent laryngeal nerve
What is the purpose of the recurrent laryngeal nerve?
Sensory to below the vocal cords
Motor to all intrinsic muscles of the larynx (except cricothyroid muscle)
How else could the recurrent laryngeal nerve be damaged?
- apical cancer of the lungs
- aortic arch aneurysm
What happened in a unilateral vocal cord palsy?
- damaged cord in the paramedian position
- ineffective cough and hoarseness of voice
- the contralateral side compensates in time (could cross the midline to meet the vocal cord on the affected side)
Why is a bilateral vocal cord palsy a medical emergency?
- both vocal cords are stuck in the middle
- narrowed glottis = airway obstruction
How would someone with a compromised upper airway present?
- present of strider
- raised respiratory rate
- distress
- hypoxia
- possible cyanosis
