Muscles of the larynx Flashcards
Where are most of the intrinsic muscles of the larynx located?
Within the larynx
deep to the thyroid cartilage
What are the actions of the intrinsic muscles of the larynx?
Move the aretynoid cartilage on cricoid cartilage at the cricoaretynoid joint
moves the true vocal cords
changes the diameter of the rima glottidis
What is the innervations of most of the intrinsic muscles of the larynx?
Recurrent laryngeal nerve
What does the recurrent laryngeal nerve branch off?
CN10 vagus nerve
How does the recurrent laryngeal nerve ascend up the neck?
In the tracheo-oesophageal groove
What is a close anatomical relation of the recurrent laryngeal nerve?
Inferior thyroid artery
Aortic arch
Apex of lung
What does the recurrent laryngeal nerve innervate apart from the intrinsic muscles of the larynx?
Sensory innervation to infraglottis
What are two important intrinsic laryngeal muscles?
Posterior cricoaretynoid muscle
Cricothyroid muscle
What does the posterior cricoaretynoid muscle attach to?
Cricoid cartilage posteriorly
Aretynoid cartilage
What is the innervation of the posterior cricoaretynoid muscle?
Recurrent laryngeal nerve
What is the action of the posterior cricoaretynoid muscle?
Abducts vocal cords
What is special about the posterior cricoaretynoid muscle?
Only intrinsic muscle of the larynx that abducts the vocal cords
What does the cricothyroid muscle attach to?
Cricoid cartilage anteriorly
Thyroid cartilage anteriorly
What is the innervation of the cricothyroid muscle?
Superior laryngeal nerve
external branch
What is the action of the cricothyroid muscle?
Bilateral contraction
tilts the thyroid cartilage anteriorly over the cricoid cartilage
increases tension of vocal cords
higher pitched sound
What is special about the cricothyroid muscle?
Only intrinsic muscle of larynx to be found outside of larynx
Only intrinsic muscle of larynx not innervated by the recurrent laryngeal nerve
How does tension and length of true vocal cords affect pitch of vocal sounds?
Increased tension and length gives high pithced vocal sounds
Decreased tension and length gives low-pitched vocal sounds
What does the superior laryngeal nerve branch off?
CN10 vagus nerve
What are the branches of the superior laryngeal nerve itself?
External branch
Internal branch
What is a close anatomical relation of the external branch of the superior laryngeal nerve?
Superior thyroid artery
What does the internal brach of the superior laryngeal nerve innervate?
Sensory innervation to supraglottis
What happens to the vocal cords during inspiration and expiration?
Abduct
What happens to the rima glottidis when the vocal cords abduct?
Increased diameter
What does the level of abduction of the true vocal cords during inspiration and expiration depend on?
How deep the breathing is
more abduction if deeper breathing
What happens to the vocal cords during phonation?
Adduct
What happens to the rima glottidis when the vocal cords adduct?
Decreased diameter
Why are the vocal cords adducted during phonation?
Expired air forced through closely adducted vocal cords
vocal cords vibrate
gives pitch of voice
What happens to the epiglottis when swallowing?
Aryepiglottic muscles contract
pull down epiglottis over the laryngeal inlet
Why does the epiglottis cover the laryngeal inlet when swallowing?
To prevent aspiration
What happens to the larynx itself during swallowing?
Pharyngeal muscles and suprahyoid muscles contract
pull larynx upwards and forwards
What happens to the vocal cords during swallowing?
Adduct
Why do the vocal cords adduct during swallowing?
To prevent aspiration
What happens to the vocal cords during a cough?
Adducted for a while
then suddenly abduct
What happens when the vocal cords are adducted during a cough?
Intrathoracic pressure builds up
What happens when the vocal cords suddenly abduct during a cough?
Air is expired rapidly and forcefully
