Larynx Flashcards
What are the functions of the larynx?
Phonation, cough reflex, protection of the lower respiratory tract
What is the larynx suspended by?
Hyoid bone
How is the larynx covered anteriorly?
By infrahyoid muscles
How is the larynx covered laterally?
By lobes of the thyroid gland
What 3 sections can the internal cavity of the larynx be divided into?
Supraglottis - from inferior surface of epiglottis to vestibular folds
Glottis - vocal cords and 1cm below them
Subglottis - from inferior border of glottis to inferior border of the cricoid cartilage
What is the opening between the vocal cords known as?
Rima glottidis
What is the arterial supply to the larynx?
Superior and inferior laryngeal arteries
What is the superior laryngeal artery derived from?
Branch of superior thyroid artery - derived from external carotid
What is the inferior laryngeal artery derived from?
Branch of inferior thyroid artery - derived from thyrocerivcal trunk
Which nerve does the superior laryngeal artery follow into the larynx?
Internal branch of the superior laryngeal nerve
Which nerve does the inferior laryngeal artery follow into the larynx?
Recurrent laryngeal nerve
Describe the sensory innervation to the larynx
Recurrent laryngeal nerve - infraglottis
Internal branch of the superior larngeal nerve - supraglottis
Describe the motor innervation to the internal muscles of the larynx
Recurrent laryngeal nerve - all muscles except cricothyroid
External branch of the superior laryngeal nerve - cricothyroid
What nerve is at risk during thyroid surgery?
Recurrent laryngeal nerve
Which part of cartilages move the vocal cords?
Arytenoid cartilages
Which is the only complete ring of cartilage?
Cricoid cartilage
What is the false vocal cord?
Vestibular ligament
What is the true vocal cord?
Vocal ligament
What type of epithelium lines the larynx?
Pseudostratified ciliated columnar epithelium
What is the gap between the 2 true vocal cords?
Rima glottidis
How do you orient anterior and posterior on a laryngoscopy?
Point of rima glottidis is forward (anterior)
What do the vocal cords do during inspiration and expiration?
Abduct (true vocal cords abduct to greater extent during deep breathing)
What do the vocal cords do during phonation?
Adduct (expired air is forced through closely adducted vocal cords to vibrate a column of air)
What happens to the vocal cords during a cough?
Vocal cords are powerfully adducted, intrathoracic pressure builds, then cords are suddenly abducted
How can the pitch of vocal sounds be altered?
By tension and length of true vocal cords
High pitch - vocal cords taut
Low pitch - vocal cords relaxed
Contraction of which muscle increases length and tension in vocal cords?
Cricothyroid (important for high pitch)
What innervates cricothyroid?
External branch of superior laryngeal nerve
What is seen in an injury to the superior laryngeal nerve?
Innervates cricothyroid
Hoarseness of voice especially when attempting high pitched sounds
What does the larynx do during swallowing?
Contraction of aryepiglottic muscles acts to narrow laryngeal inlet and pull down epiglottis, assisted by elevation of larynx, closure of vocal cords
Which nerve could become compressed as a result of an aortic arch aneurysm?
Left recurrent laryngeal nerve
What position does a paralysed vocal cord assume?
Paramedian position - between fully abducted and fully adducted
What symptoms could be produced as a result of a unilateral vocal cord palsy?
Hoarseness of voice, ineffective cough
note that contralateral side often compensates in time by crossing the midline to meet affected vocal cord
Which vocal cord palsy is an emergency: unilateral or bilateral?
Bilateral
Both vocal cords in paramedian position - narrow glottis - significant airway obstruction
How will a patient with a compromised upper airway present?
Stridor, raised respiratory rate, distress, hypoxia +/- cyanosis
