17 - Head + Neck - Larynx

Question 1

What are the superior and inferior boundaries of the larynx?

Answer 1

Sup: Hyoid bone (C4)
Inf: Trachea (C6)

Question 2

What are the functions of the larynx?

Answer 2

• Phonation
• Respiration
• Protection of airways
• Cough reflex

Question 3

What are the zones of the larynx, and their corresponding sensory innervation:

Answer 3

Supraglottis = Internal laryngeal nerve
Glottis
Subglottis = Recurrent laryngeal nerve

Question 4

What are the cartilages of the larynx?

Answer 4

• Epiglottis
• Thyroid
• Cricoid
• Arytenoids

Question 5

Which membrane of the larynx is can be punctured to establish an emergency airway?

Answer 5

Cricothyroid membrane

Question 6

What is the name of the point where the 2 lateral plates of the thyroid cartilage meet?

Answer 6

Laryngeal prominence ‘adam’s apple’

Question 7

Name the only complete ring of cartilage in the respiratory tract:

Answer 7

Cricoid cartilage

Question 8

Broadly, how do the intrinsic laryngeal muscles affect the arytenoids?

Answer 8

The muscles cause the arytenoids to pivot on the cricoid cartilage, causing the vocal cords to abduct/adduct/tense

Question 9

Name the 2 mucosal folds lining the interior of the larynx:

Answer 9

Most superior = vestibular fold (false vocal cord)

Inferior = true vocal cord (contains vocal ligament)

Question 10

Name the 5 intrinsic muscles of the larynx:

Answer 10

1) Cricothyroid
2) Post. cricoarytenoid
3) Lat. cricoarytenoid
4) Thyroarytenoid
5) Transverse + Oblique arytenoids

Question 11

Which muscle is responsible for changing pitch during phonation (particularly high pitch sounds)? What is its nerve supply?

Answer 11

Cricothyroid

Ext. superior laryngeal (CN X)

Question 12

Which muscle can abduct the vocal cords, therefore required for respiration? What is its nerve supply?

Answer 12

Post. cricoarytenoid

Recurrent laryngeal (CN X)

Question 13

Which nerve innervates all (except one) of the intrinsic muscles of the larynx? What is the exception?

Answer 13

Recurrent laryngeal nerve

Exception = Cricothyroid = Ext. superior laryngeal

Question 14

Describe the position of the vocal cords during:

• Phonation
• Respiration
• Coughing
• Swallowing

Answer 14

ADDUCTED = phonation, coughing, swallowing

ABDUCTED = respiration

Question 15

What happens to the corresponding vocal cord if the left recurrent laryngeal nerve is cut? How will this present?

Answer 15

• Immobilise in neutral position between abduction and adduction
• Hoarse voice, weaker cough

Question 16

What happens to the vocal cords if both the recurrent laryngeal nerves are cut? How will this present?

Answer 16

• Both vocal cords immobilise in neutral position
  = Rima glottis becomes extremely narrow
• Aphonia, obstructed breathing, unable to protect airway during swallowing

Question 17

Name some concerning causes of a hoarse voice:

Answer 17

• Left apical lung tumour (pancoast)
• Aortic aneurysm
• Enlarged lymph nodes in trachea-oesophageal groove
• Carcinoma of larynx
• Stroke
• MS

Question 18

Which nerves make up the cervical plexus, and in which triangle of the neck is it located?

Answer 18

C1-4

Posterior

Question 19

Name the main 2 motor branches of the cervical plexus, their roots and target:

Answer 19

Phrenic = C3, 4, 5 –> Diaphragm

Ansa cervicalis = C1, 2, 3 –> Infrahyoids

Question 20

Name the main 4 sensory branches of the cervical plexus, and their targets:

Answer 20

• Greater auricular –> Ear
• Transverse cervical –> Anterior neck
• Lesser occipital –> Post-Sup scalp
• Supraclavicular –> Upper thoracic region