The Larynx

Question 1

Describe the functions of the larynx. (4)

Answer 1

Airway protection when swallowing.
Ventilation
Phonation
Cough reflex role.

Question 2

Describe the location of the larynx. (2)

Answer 2

Suspended from the hyoid bone, begins at the laryngeal inlet, and ends at the lower border of the criocoid cartilage (C6)

Question 3

Explain how food can easily end up in the respiratory tract. (3)

Answer 3

Air: oral cavity/nasopharynx > oropharynx > larynx > trachea
Food: oral cavity > oropharynx > laryngopharynx > oesophagus.
Shared pathway, both pass trough the oropharynx.

Question 4

Describe the cartilages of the larynx. (8)

Answer 4

Three single cartilages:
Thyroid - shield shapes, forms Adam’s apple.
Cricoid - complete ring, signet shaped, beneath the thyroid cart.
Epiglottis - ligamentous attachment to the thyroid cartilage.
One paired cartilage:
Arytenoid - pyramindal, posterior, attached to the large signet bit of cricoid.

Question 5

Describe the membranes/ligaments of the larynx. (9)

Answer 5

They link the cartilages and the hyoid bone.
Thyrohyoid membrane
Cricothryoid membrane - emergency access here.
Cricotracheal membrane
Quadrangular membrane - forms the vestibular ligament which forms the false vocal cords (first set of cords seen)
Cricothyroid ligament - forms the true vocal cords (second set of cords seen).
Aryepiglotic folds - triangular folds of membrane located at the entrance of the larynx, from the epiglottis to the arytenoid cartilages.

Question 6

Describe the position of the larynx in relation to the laryngopharynx. (3)

Answer 6

The larynx lies anterior to the laryngopharynx. The cross over begins at epiglottis and extends to the false vocal cords at the bottom of the aryepiglotic folds.

Question 7

Describe the divisions of the larynx. (3)

Answer 7

Supraglottis - epiglottis to false vocal cords
Glottis - true vocal cords
Infraglottis - below true vocal cords to lower edge of cricoid cartilage.

Question 8

Describe the epithelium of the larynx. (2)

Answer 8

Most is pseudostratified ciliated columnar (respiratory), except true vocal cords which are squamous.

Question 9

Explain the differences between intubation and nasoendoscopy. (2)

Answer 9

Intubation needs a view of the true vocal cords to place a breathing tube in the subglottic region.
Nasoendoscopy is a camera passed nasal cavity > pharynx > larynx to view these structures.

Question 10

Describe the functions of laryngeal muscles. (4)

Answer 10

Can alter size and shape of the inlet, or size and Position of the vocal cords.
Closing the laryngeal inlet when swallowing.
Open vocal cords to allow breathing.
Movements of vocal cords in phonation and cough reflex.

Question 11

Describe the intrinsic muscles of the larynx. (5)

Answer 11

All the intrinsic muscles of the larynx adduct the vocal cords except posterior cricoarytenoid which abducts.
All the intrinsic muscles are supplied by the recurrent laryngeal nerve of vagus except cricothyroid which is supplied by the superior laryngeal nerve.
The muscles generally move the arytenoids on the cricoid cartilage because this changes the rima glottidis - laryngeal inlet.

Question 12

Explain the position of the vocal cords in these actions. (6)
During inspirations and expiration
Phonation
Cough

Answer 12

During inspirations and expiration - abduct to allow lots of air in and out.
Phonation - adduct to allow a thin column of fast-vibrating air
Cough - powerfully adduct then suddenly abduct following an increase in intrathoracic pressure to push the obstruction out.

Question 13

Describe how to change the pitch of the voice. (2)

Answer 13

High pitched: taut vocal cords

Low pitched: relaxed vocal cords

Question 14

Describe the action of the cricothyroid muscle. (2)

Answer 14

Increases both tension and length of the vocal cords because it tilts the thyroid cartilage forwards on the cricoid cartilage.

Question 15

Describe the nerve supply to the larynx. (4)

Answer 15

Sensory infraglottis - recurrent laryngeal nerve
Sensory supraflottis - superior laryngeal.
Motor to intrinsic muscles - recurrent laryngeal
Motor to cricothyroid - superior laryngeal

Question 16

Describe vocal cord palsies and their possible causes. (5)

Answer 16

Paralysis to the recurrent laryngeal nerves leaves vocal cords in a paramedian position.
This is fine if unilateral (hoarseness of voice and ineffective cough) but life threatening if bilateral (airway obstruction).
Can be caused by thyroid surgery (both), aortic arch aneurysm (left), pancoast tumour(right)

Question 17

Explain two reasons to have a weak cough. (4)

Answer 17

One vocal cord paralysed, so assumes a paramedian position. This cannot powerfully adduct to allow for the build up of pressure behind it, so the cough is ineffective.
Weak expiratory muscles due to eg a spinal cord lesion, means the muscles can’t contract to produce the high pressure so the cough is weak.

Question 18

Describe 6 conditions of the larynx.

Answer 18

Laryngitis - inflammation of the vocal cords
Laryngeal nodules
Laryngeal cancer
Croup - viral URTI leading to cough and stridor.
Epiglottitis - infection of the epiglottis.
Laryngeal oedema - allergic reaction