Session 11

Question 1

What are the 3 functions of the larynx?

Answer 1

Respiration, phonation, swallowing

Question 2

Describe the features of the epiglottis

Answer 2

2 surfaces, 2 epithelial types
Attached to the thyroid cartilage by the thyroepiglottic ligament and to the body of the hyoid. The sides are connected to the arytenoids by aryepiglottic folds that run backwards to form the margins of the entrance of the larynx
Elastic fibrocartilage

Question 3

What is the vallecula?

Answer 3

Depression between tongue base and epiglottis

Question 4

Describe the changes involving the larynx during swallowing

Answer 4

Epiglottis pulled down, larynx pulled up and forward, food bolus directed lateral to epiglottis into piriform fossae

Question 5

What are the 3 areas of the larynx?

Answer 5

Supraglottis/vestibule - above false vocal cords
Glottis - between false and true vocal cords
Subglottis - between true vocal cords and first tracheal ring

Question 6

What forms the structural framework of the larynx?

Answer 6

Epiglottis, thyroid, cricoid and arytenoid cartilages

Question 7

What is the thyroid cartilage attached to?

Answer 7

Superiorly to the hyoid bone by the thyrohyoid membrane, and inferiorly to the cricoid cartilage by the cricothyroid membrane

Question 8

Describe the structure of the thyroid cartilage

Answer 8

Made up of two lateral plates meeting in the midline as a prominent ‘V’ called the laryngeal prominence.

Question 9

Describe the structure of the cricoid cartilage and its attachments

Answer 9

Signet-ring shaped and the only complete ring of cartilage throughout the respiratory tract. Inferiorly, it is attached to the trachea by the cricotracheal membrane.

Question 10

Where do the arytenoids sit?

Answer 10

On top of the cricoid cartilage posteriorly, one on each side

Question 11

Where do the vestibular folds (false vocal cords) and true vocal cords attach?

Answer 11

From thyroid cartilage to arytenoids. Vestibular folds are more superior

Question 12

What do the true vocal cords contain?

Answer 12

The vocal ligament - a thickening of the cricotraceal membrane

Question 13

What is the name of the space between the vocal cords?

Answer 13

Rima glottidis

Question 14

What is the general function of the intrinsic muscles of the larynx

Answer 14

open the glottis in inspiration, close the vestibule during swallowing and alter the tone of the true vocal cords in phonation

Question 15

What is the only intrinsic muscle of the larynx to be found outside of the larynx and what is its function?

Answer 15

Cricothyroid - tensing the vocal cords by its tilting action of the thyroid cartilage on the cricoid cartilage to allow higher pitched sounds can be made

Question 16

Describe the innervation of the intrinsic muscles of the larynx

Answer 16

Cricothyroid - external laryngeal nerve (a branch of superior laryngeal nerve - CNX)
Rest - recurrent laryngeal nerve (CNX)

Question 17

Describe the action of the intrinsic muscles of the larynx on the cricoarytenoid joint

Answer 17

The posterior cricoarytenoid on each side, rotates the arytenoids abducts the vocal cords.
The rest adduct

Question 18

What muscles ensure that the laryngeal inlet is safely covered by the epiglottis

Answer 18

A number of the intrinsic muscles attach to the
epiglottis, and their contraction pulls down on the sides of the epiglottis so that it covers over the laryngeal inlet. The contraction of the suprahyoid muscles and pharyngeal muscles pull the larynx upwards,
helping tilt the epiglottis further.

Question 19

Describe the neurovascular supply to the larynx and what is the relevance of the relationship between the nerves and arteries

Answer 19

The superior laryngeal nerve innervates the laryngeal mucosa above the vocal cords, while the recurrent laryngeal nerve innervates the mucosa below the vocal cords. These nerves are accompanied by arterial branches from the superior and inferior thyroid arteries. This relationship is important when operating on the thyroid gland (e.g. thyroidectomy), to avoid causing a vocal cord paralysis.

Question 20

Describe the effects of a unilateral complete injury to the recurrent laryngeal nerve

Answer 20

The vocal cord on the affected side will become immobile and take up a neutral position between abduction and adduction. As the opposite cord is unaffected, it is able to compensate quite well, though there may be some hoarseness and a weaker cough

Question 21

Describe the effects of a bilateral complete injury to the recurrent laryngeal nerve

Answer 21

Both vocal cords assume the paramedian position, with the rima glottidis becoming extremely narrow but not completely closed. Aphonia and stridor

Question 22

Why can lesions that progressively involve both the recurrent laryngeal nerves, or only bruise the nerves present a greater threat to the airway than a complete division of the nerves?

Answer 22

In partial injury to the recurrent laryngeal nerve the abductor muscles are paralysed before the adductors.
Therefore the vocal cords are adducted together causing a significant obstruction to air moving in and out of the trachea

Question 23

What procedure should be performed should the two vocal cords significantly impede air flow?

Answer 23

Emergency tracheostomy

Question 24

What can cause recurrent laryngeal nerve palsy?

Answer 24

Idiopathic, laryngeal cancer, thyroid disease, trauma (including iatrogenic - thyroidectomy), cervical lymphadenopathy, oesophageal cancer, apical lung cancer, aortic aneurysm

Question 25

Which carcinomas of the larynx have a poorer prognosis and why?

Answer 25

Those involving the supra and infra glottic regions because the lymph drains to neck and paratracheal lymph nodes respectively. Glottis doesn't have much lymphatic drainage.

Question 26

What are the clinical features of laryngeal cancer?

Answer 26

``` Smoking and alcohol Hoarseness Dysphagia Weight loss Coughing ```

Question 27

What forms the cervical plexus and where does it lie?

Answer 27

The anterior primary rami of the first four cervical nerves. It lies on the surface of scalenus medius and levator scapulae muscles, deep to the internal jugular vein and emerges from the posterior border of sternocleidomastoid, to lie within the posterior triangle

Question 28

Describe the sensory and motor functions of the cervical plexus

Answer 28

Sensory - skin of the neck, part of the scalp and ear, and the superior part of the thorax. Muscular - a number of the muscular branches form a loop known as the ansa cervicalis, which gives rise to nerves supplying most of the four paired infrahyoid muscles. Also gives off the phrenic nerve, which carries nerve roots from C3-5 (diaphragm)