H&N19 - Anatomy of the Larynx

Question 1

4 functions of the larynx

Answer 1

1. ) Airway Protection - prevents aspiration of food/fluid into the airways
2. ) Cough Reflex - rapidly expel anything inadvertently entering the airway
3. ) Ventilation - movement of air into and out of the lungs
4. ) Phonation - role in production of sound

Question 2

4 anatomical features of the larynx

Answer 2

1. ) Begins at the laryngeal inlet and ends at the lower border of the cricoid cartilage (C6)
2. ) Suspended from and lies below the hyoid bone
3. ) Continues as the trachea
4. ) Anterior to the laryngopharynx

Question 3

cartiliages, membranes and ligaments of the larynx

Epiglottis
Arytenoid Cartilages
Cricoid Cartilage
Cricothyroidotomy

Answer 3

1. ) Epiglottis - leaf shaped flap attached to the inner surface of the thyroid cartilage
   - closes during swallowing to prevent food aspiration
2. ) Arytenoid Cartilages - pair at the back of the larynx
   - position in cricoid determines position of the true vocal cords therefore the size of the rima glottidis
3. ) Cricoid Cartilage - surrounds the trachea
   - complete ring unlike the thyroid cartilage
   - cricothyroid membrane separates the thyroid and cricoid cartilage
4. ) Cricothyroidotomy - incision through the cricothyroid membrane to provide emergency access to the airway
   - perfomed when a patient cannot be intubated or ventilated e.g. due to swelling of vocal cords

Question 4

3 divisions of the larynx

Answer 4

1.) Supraglottis - from the laryngeal inlet to the false vocal cords

2. ) Glottis - narrowest part from the false vocal cords to and including the true vocal cords
   - contains the ventricle and saccule of larynx

3.) Infraglottis - from the true vocal cords into the trachea (lower border of the cricoid cartilage, C6)

Question 5

Actions of the intrinsic muscles of the larynx during…

Swallowing
Inspiration and Expiration
Phonation
Coughing

Answer 5

1.) Swallowing - close the vocal cords and laryngeal inlet to protect the respiratory tract

2. ) Inspiration and Expiration - open the vocal cords and laryngeal inlet allowing movement of air
   - posterior cricoarytenoid is the only intrinsic muscle that acts to open (abduct) the vocal cords
3. ) Phonation - closely adduct the vocal cords
   - expired air is forced through closely adducted vocal cords causing vibration which creates sound waves
   - the higher pitch the sound, the more taut the VCs are
   - cricothyroid muscle contracts to increase VC tension
4. ) Cough - explosion of compressed air
   - inspire and fill lungs with air and then the VCs close
   - expiratory muscles contract to increase intrathoracic pressure and the the VCs then suddenly open (abducted)
   - this causes explosive outflow of air

Question 6

3 vagus nerve branches supplying the larynx

Answer 6

1. ) Internal Branch of Superior Laryngeal Nerve - CN X
   - general sensory to the supraglottis and glottis
2. ) External Branch of Superior Laryngeal Nerve - CN X
   - motor to the cricothyroid muscles
   - nerve injury causes hoarseness of voice, especially when attempting higher pitch sounds
3. ) Recurrent Laryngeal Nerve - CN X
   - general sensory to the infraglottis
   - motor to the rest of the intrinsic muscles of the larynx

Question 7

3 features of recurrent laryngeal nerve (RLN) palsies

Anatomical Relations to the RLN x5
Unilateral RLN Lesions
Bilateral RLN Lesions

Answer 7

1. ) Anatomical Relations - can damage the RLN
   - inferior thyroid artery: injured during thyroid surgery
   - aortic arch: aneurysm can damage the left RLN
   - apex of lung: cancer can damage RLN
   - larynx or oesophagus: disease or surgery
2. ) Unilateral RLN Lesions –> unilateral VC palsies
   - both VCs have to adduct for phonation and cough so if only one is impaired, both actions will be impaired
   - hoarse voice and ineffective cough
   - often the contralateral side compensates by crossing the midline to meet VC on affected side
3. ) Bilateral RLN Lesion - both vocal cords paralysed and in paramedian position, narrowing the glottis
   - causes significant airway obstruction and requires emergency surgical intervention

Question 8

4 features of swelling of the larynx

Signs and Symptoms x7
Causes x6
Epiglottitis
Croup

Answer 8

1. ) Signs and Symptoms - threatens the airway
   - stridor, raised RR, hypoxia +/- cyanosis, distress
   - may also have hoarse voice and ineffective cough
2. ) Causes
   - laryngitis (inflammation of the VCs), epiglottitis
   - laryngeal nodules, cancer or oedema (allergic reaction)
   - croup
3. ) Epiglottitis - inflammation of the epiglottis
   - life-threatening if complete airway obstruction
   - symptoms: sore throat, painful swallowing, difficulty swallowing fluids, muffled voice, fever
   - should not have throat manually examined or bloods taken as pain and interference can cause the epiglottis to snap shut causing laryngeal obstruction
   - need laryngoscopy (ready w/ equipment if epiglottis does shut)
4. ) Croup - common childhood viral infection causing inflammation of the larynx and trachea
   - symptoms: harsh barking cough, hoarse voice, stridor

Question 9

4 features of the vocal cords

False Vocal Cords
True Vocal Cords
Ventricle
Saccule of Larynx

Answer 9

1. ) False Vocal Cords - vestibular ligament (fixed)
   - free lower border of the quandrangular membrane
2. ) True Vocal Cords - vocal ligament (mobile)
   - free upper border of the cricothyroid membrane
   - the rima glottidis is the gap between the 2 vocal cords
   - lined w/ stratified squamous epithelium
3. ) Ventricle - small recess between the vestibular and vocal folds that leads into the saccule of the larynx
4. ) Saccule of Larynx - contains mucous glands that keep the true vocal cords moist