Session 11 - The Larynx Flashcards
What does the larynx connect?
The oropharynx to the trachea
What does the larynx contain?
The voice box
Where does the larynx extend to and from?
Laryngeal inlet (communicates with laryngopharynx) to the level of the inferior border of the cricoid cartilage, at which point it is ocntinous with trachea.
Give three functions of the larynx
- Protective sphincter – Open during respiration, closed during swallowing
- Required for effective cough reflex
- Phonation – Vibration of vocal cords as air flows through the narrowed glottis in expiration
What does articulation require?
Lips, tongue, pharynx and larynx
What does resonance require?
Larynx, pharynx, oral and nasal cavities and sinuses
What is the overall structure of the larynx?
Hyoid bone and 9 cartilages
What are the cartilages of the larynx?
o 3 Unpaired Cartilages Epiglottis Thyroid Cartilage Cricoid Cartilage o 1 important set of Paired Cartilages Arytenoid Cartilage(s) o 2 other sets of Paired Cartilages Corniculate Cartilage(s) Cuneiform Cartilage(s)
What is the epiglottis?
Fibrocartilage
What is epiglottis attached to and from?
By ligaments to back of bhyoid bone and thyroid cartilage
Where the thyroid cartilage located?
C4 level
What is the use of the location of the thyroid cartilage
C4 is point of bifurcation of common carotid and the level of the carotid body
What is the structure of the thyroid cartilage?
Two large lamina
2 horns
What are the two horns of the thyroid cartilage connected to respectively?
Superior Thyroid Horns Ligament Hyoid Bone
Inferior Thyroid Horn Synovial Joint with Cricoid
What is thyroid cartilage suspended by?
Thyrohyoid membrane
What is the shape of the cricoid cartilage?
Signet ring shape
What is the anatomical significance of cricoid cartilage?
Surface marking for C6 level (carotid pulse)
What are the arytenoid cartilages used for?
Vocal cord movement
What is anterior and what is lateral to the arytenoid cartilage?
o Anterior – Vocal process
o Lateral – Muscular process
What is the cricovocal membrane?
Made up of elastic fibres
Upper free border is the vocal ligament
What are the three spaces of the laryngeal cavity?
Supraglottic space
Glottis
Subglottic space
What is the supraglottic space?
Laryngeal inlet -> Vestibular folds (false vocal cords)
What is the glottis?
Vocal cords and rima glottis (space between vocal cords)
What is the subglottic space
Below vocal cords -> lower border of cricoid cartilage
What are the extrinsic muscles of the larynx and what is there function?
o Infrahyoid muscles
Depress larynx
o Suprahyoid muscles
Elevate larynx
What are the intrinsic muscles of the larynx and what is there function?
o Vocal folds
Open and close glottis
o Aryepiglottic folds
Help to close the laryngeal inlet
What supplies the intrinsic muscles?
Recurrent laryngeal nerve, except for the cricothyroid which is supplied by external laryngeal nerve
What are the layers of the vocal cords?
o Stratified Squamous Epithelium
o Vocal (cricothyroid) Ligament
o Vocalis Muscle
Why do vocal cords look pearly white?
Mucosa firmly adhered to vocal ligament and has no sub mucosa.
Give two positives of the firmly adhered mucosa of vocal ligament
No oedema during infection
Delayed spread of carcinoma of vocal cords
Give two movements of the vocal cords
Abduction (open)
Adduction (closed
What muscle controls true vocal cords?
Posterior cricoarytenoid (only abductor! REMEMBER)
What causes abduction of vocal folds?
Posterior cricoarytenoid
What causes adduction of vocal cords?
Lateral cricoarytenoid
What is the function of the cricothyroid, and why is it odd?
Only intrinsic muscle on the outside, increases vocal cord tension
What supplies posterior cricoarytenoid?
Reccurent laryngeal nerve
What supplies cricothyroid?
External larygeal nerve
What supplies lateral cricoarytenoid?
Recurrent laryngeal
What is the innervation of larynx derived from?
Branches of vagus
What is superior laryngeal nerve made up of? Give functions
Internal laryngeal nerve
- Sensory to larynx above true vocal cord
External laryngeal nerve
- Motor to cricothyroid
What is the recurrent laryngeal nerve? Functins?
Sensory below true vocal cord
Motor to all intrinsic laryngeal muscles
What is the path of the right recurrent laryngeal nerve?
Descends to T2
Curves around the Subclavian Artery
What is the path of the left recurrent laryngeal nerve?
Descends to T4
Curves around the Arch of the Aorta
Where do recurrent laryngeal nerves go?
Up neck, between trachea and oesophagus
What is hoarseness of voice caused by?
Intrinsic laryngeal muscle weakness for >3 weeks can be due to recurrent laryngeal nerve palsy and is called “hoarseness”
Give 6 causes of hoarseness
Infection Overuse of voice GORD Benign nodules on vocal cords Apical lung tumour Bronchial carcinoma Aortic aneurysm
What do you to assess larynx?
Indirect laryngoscopy
Flexible rhinolaryngoscopy
Look for abnormalities of larynx and check movements
What would an apical lung tumour effect?
Recurrent laryngeal nerve on both sides
What is unilateral RLN palsy?
Affected vocal cord does not move
Its position is paramedian
Cannot narrow glottis during speach
What would a bronchial carcinoma effect?
Left recurrent laryngeal nerve palsy (right does not go low enough)
Outline blood supply to larynx?
External Carotid Artery Superior Thyroid Artery Superior Laryngeal Artery
Subclavian Artery Inferior Thyroid Artery Inferior Laryngeal Artery
Give three causes of laryngeal obstruction
Laryngeal oedema
Inhalation of foreign body
Tumour
Give three causes of laryngeal oedema
Acute epiglottitis
Croup
Anaphylaxis
Why does laryngeal cancer have a good prognosis?
Presents with hoarseness of voice quickly
How does you treat laryngeal obstruction?
Emergency cricothyroidotomy (opening into airway through the cricothyroid membrane)
Why is thyroid artery significant during thyroidectomy?
Superior thyroid artery ligation may damage superior laryngeal nerve
Inferior thyroid artery is ligated, recurrent laryngeal nerve may be damaged
ADD IN LARYNGOSCOPY
