Larynx Flashcards
What are the functions of the larynx?
Primarily protects the tracheobronchial tree
Prevents ingress of fluids & solids
Enables phonation
Regulation of pressure in thorax & abdomen
What controls speech articulation?
Pharynx
Soft palate
Tongue
Lips
Where from the larynx start and finish?
At hyoid bone (C3)
To cricoid cartilage (C6/7)
What is the larynx made up of?
Multiple cartilages & one bone
What are the cartilaginous aspects of the larynx?
Epiglottis
Thyroid
Arytenoid
Cricoid
How are the structures in the neck named?
From inferior -> superior structure e.g. thyrohyoid membrane goes from the thyroid cartilage -> hyoid bone
What can the cricothyroid membrane be used for in an emergency?
To access airways directly if you cannot go through mouth due to blockage e.g. inflammation, glossitis, trauma
Good place to intubate too as its below the vocal chords
Why might a hyoid bone fracture be fatal?
Instantaneous bleeding & swelling will occur over the top of the airways so you may suffocate quickly
What are the arytenoid cartilages and what do they do?
Pyramidal shaped cartilages that form a mobile attachment point for the vocal ligaments as they articulate with the cricoid cartilage via synovial joints allowing pivoting movements
Also connects to muscles via muscular processes to allow control of movement
Where are the vocal ligaments?
Free upper thickened edge of cricovocal membrane attaching to the thyroid cartilage anteriorly & the arytenoid cartilage posteriorly
What are the 2 strong membranes of the larynx and where are they?
Aryepliglotic: passes from top of arytenoids to epliglottis & extends inferiorly; free lower border forms vestibular ligament
Cricovocal (conus elasticus): passes from cricoid cartilage & vocal process of arytenoid to thyroid cartilage anteriorly & cricoid inferiorly
What are the larynx membranes covered by?
Respiratory mucosa
What type of epithelium covers the vocal ligaments? Why?
Stratified squamous as it needs to resist damage that constant strong movements may cause
What are the ventricle & saccule?
Mucosal pouch between vestibular & vocal ligament allowing vocal ligament to move independently from vestibular fold above
What is another name for the vestibular fold? Why?
False vocal chords as they don’t hit together to make sound, they just allow the vocal fold to do this instead
What is the rima glottides?
Gap between vocal folds allowing air in
What difficulties would vocal nodules cause?
Vocal ligaments would find it harder to hit together = harder to phonate
Where is the aryepiglottic muscle? What does it do?
Found within the aryepiglottic fold (superior part of aryepiglottic membrane) & muscle around the laryngeal inlet
When it contracts, it reduces the size of the laryngeal inlet in a circular fashion
All motor and sensory innervation of the larynx if from __ __?
CN X (vagus)
What is the innervation of the larynx?
Superior laryngeal nerve (SLN) innervates above vocal chords & cricothyroid; above vocal cord it is called internal LN (sensory) & at cricothyroid it called external LN (motor)
Recurrent LN provides sensory below vocal folds & provides motor to every other muscle in the larynx
All nerve supplies are ipsilateral
What is unique about the recurrent laryngeal nerve (RLN)?
It comes off of the vagus down in the thorax, goes round & comes back up into the larynx
What procedure may endanger the superior laryngeal nerve (SLN)? Why?
Thyroidectomy (OR any thyroid op)
Because exterior branch of SLN very close to the superior thyroid artery (STA) which is ligated during thyroid surgery
What is the function of the cricothyroid muscle?
Pulls thyroid cartilage forward & down
Lengthens & tightens vocal ligaments/chords -> raises pitch of voice
What are the functions of the other muscles in the larynx (excluding cricothyroid)?
Posterior cricoarytenoid: abducts (opens) vocal ligaments widening the rima glottides so air can come in e.g. deep inspiration
Lateral cricoarytenoid: adducts (closes) vocal ligaments narrowing the rima glottides increasing pressure e.g. swallowing
Thyroartenoid & vocalis: pull arytenoid cartilage anteriorly & thyroid cartilage posteriorly/superiorly relaxing vocal fold lowering pitch of voice
What can happen if the recurrent laryngeal nerve (RLN) becomes damaged?
Loss of function = vocal fold paralysis
Unilateral injury: hoarse/altered/weakened voice
Bilateral injury: cords paralysed in mid abduction-adduction position so voice initially absent & later weak; floppy cords can block respiratory tract = emergency
How can the recurrent laryngeal nerve (RLN) become damaged?
Surgery on thyroid, anterior neck or thorax
Can be compressed by mediastinal tumours
What would happen if the superior laryngeal nerve (SLN) was damaged?
Paralysis of cricothyroid muscle causing a monotonous voice (especially when singing)
Sensation loss above vocal chords so you can aspirate food as you have no mechanism to protect airways (very dangerous!)
Why is the thyroid cartilage more prominent in males than females?
Anterior tilt
Also called the adams apple
Whereabouts are the vocal ligaments? What do they do to allow up to phonate?
At the level of the thyroid cartilage (C5)
Hit together hard & fast moving past each other to allow us to phonate
What is the epiglottis? What is its function?
Elastic cartilage that closes off the larynx & trachea when swallowing so we don’t aspirate liquid/food
