The Larynx

Question 1

What is the larynx and where is it found

Answer 1

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

Question 2

What are the functions of the larynx

Answer 2

Airway protection

Ventilation

Cough reflex

Production of phonation

Question 3

What structures form the larynx

Answer 3

Thyroid, cricoid and epiglottis cartilages

Arytenoid cartilage (+ corniculate and cuneiform)

Thyrohyoid, cricothyroid, cricotracheal and quadrangular membranes

Question 4

What forms the true vocal cords

Answer 4

True vocal cords/vocal ligament is formed by the free upper border of the cricothyroid membrane which thickens to form the ligament

Question 5

What do the free borders of the quadrangular membrane form

Answer 5

Upper border of quadrangular membrane forms the aryepiglottic folds

Lower border of membrane forms vestibular ligament and the false vocal cords

Question 6

What procedure is undertaken if a patient cannot be ventilated or intubated

Answer 6

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

Question 7

What epithelium line larynx

Answer 7

Larynx is lined with respiratory epithelium - pseudostratified ciliated columnar

True vocal cords lined with squamous epithelium

Question 8

What gap is found between the true vocal cords

Answer 8

Rima glottidis

Question 9

What are the functions of the laryngeal muscles

Answer 9

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

Question 10

How is the laryngeal inlet closed during swallowing

Answer 10

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

Question 11

How are the vocal cords opened

Answer 11

Posterior cricoarytenoid muscles rotate the arytenoids outwards to abduct the cords and open the inlet

Question 12

Describe the movement of the vocal cords during a cough

Answer 12

Vocal cords powerfully adduct

Intrathoracic pressure builds

Cords suddenly abduct -> have cough

Question 13

How are different pitches of sounds created by the vocal cords

Answer 13

Vocal cords are taut in high pitched sounds

Vocal cords are relaxed in low pitched sounds

Question 14

Which muscle controls the length and tension of the vocal cords, and how does it achieve this

Answer 14

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

Question 15

What is the nerve innervation to the larynx

Answer 15

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

Question 16

Name some pathologies of the larynx

Answer 16

Vocal cord palsies

Laryngitis

Laryngeal nodules

Laryngeal cancer

Croup

Epiglottitis

Laryngeal oedema

Question 17

What is a vocal cord palsy and what are the symptoms

Answer 17

Injury to the recurrent laryngeal nerve

Unilateral lesions result in hoarse voice +/- ineffective cough

Bilateral lesions present as emergency due to significant airway obstruction

Question 18

In vocal cord palsies, what position does the paralysed vocal cord assume

Answer 18

Vocal cord takes up a paramedian position between abducted and adducted

Question 19

Vocal cord palsies are usually due to the RLNs close relation to other structures in the neck, what are these

Answer 19

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

Question 20

Describe croup

Answer 20

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

Question 21

What is epiglottitis

Answer 21

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

Question 22

Why would you not examine a child with epiglottitis

Answer 22

Tests and examinations can lead to children becoming stresses

This causes the epiglottis to close further and it can become fully obstructed -> life-threatening

Question 23

What do patients with a compromised airway present with

Answer 23

Stridor

Raised resp rate

Distress

Hypoxis

+/- cyanosis