Anatomy and Disorders of the Larynx Flashcards
Where is the larynx located?
Between the hyoid bone above and the trachea below
C4-C6
What is the function of the larynx?
Ventilation
Airway protection = prevents aspiration
Allows us to cough
Sound prod = phonation
Name the 3 zones of the larynx
Supraglottis= from epiglottis to false vocal cords
Glottis = between false and true vocal cords
Infraglottis = between the true vocal cords and first tracheal ring
What makes up the structural framework of the larynx?
Epiglottis cartilage
Thyroid cartilage
Cricoid cartilage
Arytenoid cartilage
How is the thyroid cartilage attached to the hyoid bone?
Thyrohyoid membrane
How is the thyroid cartilage attached to the cricoid cartilage?
Cricothyroid membrane
What connects the cricoid cartilage to the first ring?
Cricotracheal membrane
Why is the cricoid cartilage special?
Only complete cartilage ring in the resp tract
How is the epiglottis attached to the inner surface of the thyroid cartilage?
Ligaments
Describe the arytenoid cartilages
Paired
Sit atop the cricoid cartilage
Determine the position of the true vocal cords
How does the thyroid cartilage articulate with the cricoid cartilage?
Synovial joint = movement
Trough what membrane is the airway accessed during emergency?
Cricothyroid mem
Between the cricoid cartilage and thyroid cartilage
Describe the location of the quadrangular mem and what it forms
Connects epiglottis to arytenoid cartilage and inner surface of the thyroid cartilage
Superior border forms = aryepiglottic folds = margins of oval inlet of larynx
Inferior border forms = vestibular ligament = false vocal cords
What does the larynx lie anterior to?
Laryngopharynx
What does the aryepiglottis fold form?
Margins of oval inlet of the larynx
What name is given to the entrance of the larynx?
Aditus
What forms the vocal ligament (true vocal cord)?
Thickening of the upper edge of the cricothyroid membrane
What forms the false vocal ligament?
Vestibular ligament
What forms the true vocal ligament?
Vocal ligament
Name the space between the true vocal cords
Rima glottidis
Outline the functions of the muscles of the larynx
Inspiration = open glottis
Swallowing = close vestibule and vocal cords
Phonation = alter tone of true vocal cords
Where is the cricothyroid muscle located?
Only intrinsic muscle of the larynx found outside of the larynx
Outline the nervous supply of the cricothyroid muscle
External laryngeal nerve = branch of the superior laryngeal nerve (branch of CN X).
Which nerve innervates the laryngeal mucosa?
Internal laryngeal N = mucosa above the vocal cords
Recurrent laryngeal N = mucosa below the vocal cords
Having a horse voice is a cardinal sign of what?
Laryngeal disease
Why does damage of the laryngeal nerve cause a horse voice?
Unilateral complete injury = affected side takes up neutral position (paramedian), unaffected partially compensates, resulting in some horseness
Both sides completely damaged = both vocal cords assume paramedian position = rima glottidis extremely narrow, resulting in diff breathing, speaking, coughing
What type of ep lines the larynx?
Pseudostratified ciliated columnar ep
What type of ep lines the true vocal cords?
Stratified squamous ep
In what direction does the rima glottidis point?
Anterior
When do the vocal cords ABduct?
Inspiration/expiration
When do the vocal cords ADduct?
Phonation
What structure determines the position of the true vocal cords?
Position of the arytenoids
What is the function of the cricothyroid muscle?
Bilateral contraction increases length and tension in vocal cords = important in high pitch noise
Tilts thyroid cartilage forward on cricoid = increasing tension in vocal cords = ADducting the vocal cords
Why does damage to the external laryngeal nerve cause a horse voice?
No nervous supply to the cricothyroid = no contraction of the vocal cords = especially hard to make high-pitched sounds
Outline the nerve supply to the larynx
Superior laryngeal nerve (branch of vagus)
1) Internal branch = sensory to supraglottic
2) External branch = motor to cricothyroid
Recurrent laryngeal N (branch of vagus) = all intrinsic muscles of larynx + sensory to infraglottic
What muscle contracts during swallowing and what does this result in?
Contraction of aryepiglottic muscles = narrow laryngeal inlet + pulls down epiglottis
What can cause vocal cord palsies?
Aortic arch aneurysm = L RLN
Cancer involving the apex of the lung (pancoast tumour) = R RLN
Disease/surgery involving larynx, oesophagus, thyroid
What nerve innervates the intrinsic muscles of the larynx?
Recurrent laryngeal nerve
One exception = cricothyroid muscle (external laryngeal N)
Describe croup
Parainfluenza = 80% of cases
Viral upper resp tract infection = nasopharynx inflam
Inflam may spread to the larynx and trachea = subglottal inflam
Harsh barking cough
What is epiglottitis
Inflam of the epiglottis
Life-threatening if complete obstruction of the airway occurs
Streptococcus
Present = sore throat, pain/diff swallowing, fever, tachycardia
Outline the location of the cervical plexus
posterior triangle of the neck, halfway up the SCM, and within the prevertebral layer of cervical fascia
anterior rami (divisions) of cervical spinal nerves C1-C4
Outline the relationship between the blood supply of the thyroid gland and the nerves supplying the larynx
Superior thyroid A runs next to the external branch of the superior laryngeal N
recurrent laryngeal runs behind the thyroid gland
both can be damaged due to surgery of the thyroid
