The Larynx Flashcards
What is the larynx and where is it found
Larynx is a tube created by a series of ligaments/membranes, cartilages and muscles
It lies below and attaches to the hyoid bone
It forms part of the respiratory system
What are the functions of the larynx
Airway protection
Ventilation
Cough reflex
Production of phonation
What structures form the larynx
Thyroid, cricoid and epiglottis cartilages
Arytenoid cartilage (+ corniculate and cuneiform)
Thyrohyoid, cricothyroid, cricotracheal and quadrangular membranes
What forms the true vocal cords
True vocal cords/vocal ligament is formed by the free upper border of the cricothyroid membrane which thickens to form the ligament
What do the free borders of the quadrangular membrane form
Upper border of quadrangular membrane forms the aryepiglottic folds
Lower border of membrane forms vestibular ligament and the false vocal cords
What procedure is undertaken if a patient cannot be ventilated or intubated
Cricothyroidotomy
Provides emergency access to airway to allow short term breathing for patient until another breathing pathway can be found
Access gained via cricothyroid membrane
What epithelium line larynx
Larynx is lined with respiratory epithelium - pseudostratified ciliated columnar
True vocal cords lined with squamous epithelium
What gap is found between the true vocal cords
Rima glottidis
What are the functions of the laryngeal muscles
Close laryngeal inlet and vocal cords during swallowing
Open vocal cords and allow movement of air during inspiration and expiration
Move vocal cords for phonation and cough relfex
How is the laryngeal inlet closed during swallowing
Muscles attached to epiglottis contract and pull down sides of epiglottis so it covers laryngeal inlet
Aryepiglottic muscles contract to narrow laryngeal inlet and help pull down epiglottis so it closes over inlet
Contraction of suprahyoids and longitudinal pharyngeal muscles ensures laryngeal inlet is covered by epiglottis
Elevation of larynx by pharyngeal muscles and suprahyoids pulls larynx up and forward to direct food/fluid down oesophagus
How are the vocal cords opened
Posterior cricoarytenoid muscles rotate the arytenoids outwards to abduct the cords and open the inlet
Describe the movement of the vocal cords during a cough
Vocal cords powerfully adduct
Intrathoracic pressure builds
Cords suddenly abduct -> have cough
How are different pitches of sounds created by the vocal cords
Vocal cords are taut in high pitched sounds
Vocal cords are relaxed in low pitched sounds
Which muscle controls the length and tension of the vocal cords, and how does it achieve this
Cricothyroid muscle contraction increases length and tension in the vocal cords
Cricothyroid is found outside of larynx, supplied by external branch of superior laryngeal nerve
Acts by tilting thyroid cartilage forward, onto cricoid, increasing tension in vocal cords
What is the nerve innervation to the larynx
All nerve supply is by the vagus nerve
Superior laryngeal:
- Internal - purely sensory. Sensory to supraglottic
- External - motor. Motor to cricothyroid. Nerve closely related to superior thyroid artery
Recurrent laryngeal - sensory to subglottic and motor to intrinsic muscles.
- Loops under right SCA or under arch of aorta -> ascends in tracheo-oesophageal groove
- Close relationship with thryoid gland and inferior thyroid arteries
Name some pathologies of the larynx
Vocal cord palsies
Laryngitis
Laryngeal nodules
Laryngeal cancer
Croup
Epiglottitis
Laryngeal oedema
What is a vocal cord palsy and what are the symptoms
Injury to the recurrent laryngeal nerve
Unilateral lesions result in hoarse voice +/- ineffective cough
Bilateral lesions present as emergency due to significant airway obstruction
In vocal cord palsies, what position does the paralysed vocal cord assume
Vocal cord takes up a paramedian position between abducted and adducted
Vocal cord palsies are usually due to the RLNs close relation to other structures in the neck, what are these
Inferior thyroid artery - damaged during thyroid surgery
Aortic arch - aortic arch aneurysm
Lung apex - cancer involving lung apex affecting right RLN
Disease or surgery involving larynx, oesophagus or thyroid
Describe croup
Common condition in children. Caused by inflammation of the upper resp tract as a result of a viral infection
Vocal cords are impaired -> cough and hoarse voice
Symptoms: harsh barking cough, hoarse voice, stridor
Treatment: relieve symptoms/fever, ensure adequate fluid intake
What is epiglottitis
Inflammation of the epiglottitis - may involve tissues surrouding epiglottis
Symptoms: sore throat, odynophagia, inability to swallow secretions, muffled voice, fever
Treatment: conservative with IV or PO antibiotics. Intubation may be needed
Why would you not examine a child with epiglottitis
Tests and examinations can lead to children becoming stresses
This causes the epiglottis to close further and it can become fully obstructed -> life-threatening
What do patients with a compromised airway present with
Stridor
Raised resp rate
Distress
Hypoxis
+/- cyanosis
