11.1 LArynx

Question 1

What are the borders of the larynx

Answer 1

Laryngeal Inlet, through which it communicates with the Laryngopharynx to the level of the inferior border of the cricoid cartilage, where it is continuous with trachea.

Question 2

Fucntion fo larynx?

Answer 2

Guard the air passages, especially during swallowing when it serves as the sphincter/valve of the lower respiratory tract, thus maintaining the airway.
Phonation
Cough reflex.

Question 3

Where is the larynx located? Vertebral level?

Answer 3

Anteiror compartment of neck, suspended from hyoid

C3-C6

Question 4

Describe the structure of the larynx?

Answer 4

The larynx is formed by a cartilaginous skeleton, which is held together by ligaments and membranes.

Question 5

What are the 3 sections of the larynx?

Answer 5

• Supraglottis
o From the inferior surface of the epiglottis to the vestibular folds (false vocal cords)

• Glottis
o Contains vocal cords and 1cm below them
o The opening between the vocal cords is known as rima glottides, the size of which is altered by the muscles of phonation.

• Subglottis
o From the inferior border of the glottis (+1cm) to the inferior border of the cricoid cartilage.

Question 6

What is the epithelium lining the larynx?

Answer 6

Ciliated columnar epithelium

Question 7

What makes up the laryngeal skeleton?

Answer 7

Hyoid and 9 cartilages:
3 unpaired:
Epiglottis
Thyroid
Cricoid
1 set of unpaired:
Arytenoid

Question 8

What is the pie glottis made of?
What is ti attached to?
How does it move in swallowing?

Answer 8

Fibro cartilage – elastic cartilage
Marks the entrance to the larynx

Attached by ligaments to the back of the hyoid bone and thyroid cartilage

During swallowing the epiglottis moves towards the arytenoid cartilages to close off the larynx and prevent aspiration.

Question 9

What is the upper level of the thyroid cartilage used to make.
Describe its structure.

Answer 9

• Upper surface used to Mark C4 Level
o Bifurcation of common carotid artery
o Level of carotid body
• Composed of 2 laminae, which join together anteriorly to form the laryngeal prominence.
• The posterior border of each sheet project superiorly and inferiorly to form the superior and inferior horns (cornu).

Question 10

What are the attachments of the thyroid cartilage?

Answer 10

horns
o Superior Thyroid Horns → Ligament → Hyoid Bone
o Inferior Thyroid Horn → Synovial Joint with Cricoid

Question 11

Describe the cricoid cartilage structure.
Attachements?
Vertebral level

Answer 11

•	Most inferior cartilage
•	Complete ring of hyaline cartilage
•	Consists of a broad sheet posteriorly and a much narrower arch anteriorly.
•	Completely encircles airway
•	2 Articular facets on each side
o	Inferior horn of thyroid cartilage
o	Arytenoid Cartilage
•	Surface marking for C6 Level, inferior level of the larynx

Question 12

Describe the shape and location of arytenoid cartilages.

Answer 12

• Pyramid shaped

* Sit on the cricoid cartilage

Question 13

What are the apex, base and sides of arytenoid cartilage?

Answer 13

Apex – corniculate cartilage
Base – superior border of cricoid cartilage
Vocal process – vocal ligament
Muscular process – posterior and lateral cricoarytenoid muscles

Question 14

describe the borders of the cricovocal membrane/ligament.

Answer 14

• Lower border attached to cricoid cartilage
• Upper, Free Border = Vocal Ligament
o Attached to the deep surface of the angle of the thyroid cartilage
o Vocal process of arytenoid cartilage

Question 15

What are the internal divisions of the larynx?

Answer 15

• Supraglottic space
o Laryngeal Inlet →
• Vestibular folds (false vocal cords)

• Glottis
o Vocal Cords and Rima Glottis (space between vocal cords)

• Subglottic Space
o Below vocal cords →
Lower border of Cricoid Cartilage

Question 16

Give the external laryngeal muscles.

Answer 16

•	Infrahyoid muscles
o	Depress larynx
•	Suprahyoid muscles
o	Elevate larynx
•	Stylopharyngeus (muscle of the pharynx)

Question 17

What are the functions of the internal laryngeal muscles.

Answer 17

•	Vocal folds
o	Open and close glottis
o	Control the length and tension of the vocal folds
•	Aryepiglottic folds
o	Help to close the laryngeal inlet

Question 18

What is the innervation of the intrinsic laryngeal msuces?

Answer 18

Inferior laryngeal branch of RLN
Except
Cricothyroid = external laryngeal branch of superior laryngeal nerve.

Question 19

Describe the attachment, function and innervation of cricothyroid.

Answer 19

• Cricoid cartilage → inferior horn of thyroid cartilage
• Stretches and tenses the vocal ligaments.
• Important for the creation of forceful speech.
• External laryngeal nerve

Question 20

Describe the attachment, function and innervation of thyroarytenoid.

Answer 20

• Thyroid cartilage → Arytenoid cartilage
• Relaxes the vocal ligament, allowing for a softer voice
• Inferior laryngeal nerve

Question 21

Describe the attachment, function and innervation of posterior cricoarytenoid.

Answer 21

• Cricoid cartilage → Arytenoid cartilage muscular process
• Abducts vocal folds – only muscle capable of widening the rima glottidis.
• Inferior laryngeal nerve

Question 22

Describe the attachment, function and innervation of lateral cricoarytenoid.

Answer 22

• Cricoid cartilage → Arytenoid cartilage (muscular process)
• Adducts the vocal folds, narrowing the tima glottidis, modulating the tone and volume of speech.
• Inferior laryngeal nerve

Question 23

Describe the attachment, function and innervation of transverse and oblique arytenoids.

Answer 23

• Span across from arytenoid cartilage to arytenoid cartilage
• Adducts the arytenoid cartilages, closing the posterior portion of the rima glottidis.
• Inferior laryngeal nerve

Question 24

What are the larders of the vocal cords?

Answer 24

• Stratified Squamous Epithelium
• Vocal Ligament
• Vocalis Muscle

Question 25

Significance of no submucosa in vocal cords?

Answer 25

The mucosa is firmly adherent to the vocal ligament, with no submucosa. This lack of a submucosa means that:
• Vocal cords look pearly white on laryngoscopy
• No oedema during infections
• Delayed spread of carcinoma of vocal cords

Question 26

What are the movements of the vocal cords?

Answer 26

Abduction and adduction

Question 27

What muscle abducts vocal cords?

Answer 27

Posterior cricoarytenoid.

Question 28

What muscles adduct the vocal cords?

Answer 28

Lateral cricoarytenoid

Cricothyroid increase vocal cord tension.

Question 29

What is the sensory innervation of the larynx above and below the vocal cords?

Answer 29

Above = Superior laryngeal nerve - internal laryngeal nerve
Below = RLN

Question 30

Describe the path of the RLN

Answer 30

Right:
Descends to T2 and curves around the subclavian artery

Left:
Descends to T4 and curves around arch of aorta.

Back up to larynx between trachea and oesophagus.

Question 31

What causes hoarseness of voice?

Answer 31

Unilateral RLN palsy.

Question 32

What happens in bilateral palsy of RLN?

Answer 32

Vocal cords paralysed in position between adduction and baduction.
Breathing is impaired and phonation cannot occur.

Question 33

What happens in partial damage of nerves?

Answer 33

Depending on the cause, nerve damage can be bilateral or unilateral.
In unilateral palsy, one vocal cord is paralysed.
The other vocal cord tends to compensate and speech is not affected to a great degree although the patient may experience hoarseness of voice.

Question 34

Give some causes of hoarseness of voice.

Answer 34

• Infection
o Laryngitis – Viral, Streptococcal
• Overuse of the voice
• GORD – Gastro Oesophageal Reflux
• Benign nodules on vocal cords (Singers)
• Apical Lung Tumour
o Recurrent Laryngeal Nerve Palsy (Both sides)
• Bronchial Carcinoma
o Left Recurrent Laryngeal Nerve Palsy (right doesn’t go low enough)

Question 35

Give the blood supply to the larynx.

Answer 35

External Carotid Artery → Superior Thyroid Artery → Superior Laryngeal Artery

Subclavian Artery → Inferior Thyroid Artery → Inferior Laryngeal Artery
(Follows the recurrent laryngeal nerve into the larynx)

Question 36

Give the venous drainage of the larynx.

Answer 36

superior laryngeal vein + superior thyroid vein –> IJV

Inferior laryngeal vien + inferior thyroid vein –> LEft brachiocephalic vein

Question 37

What can cause laryngeal obstruction? How is this treated in emergency?

Answer 37

• Laryngeal Oedema
o Infection – Acute epiglottitis, croup, anaphylaxis
• Inhalation of foreign body
• Tumours

In an emergency situation an airway is opening through the Cricothyroid Membrane (Cricothyroidotomy). If less urgent, a Tracheostomy is performed (opening into the trachea).