Muscles of the Larynx

Question 1

What are the vestibular ligaments ?

Answer 1

It extends from the thyroid cartilage to the arytenoid cartilage
Covered by a mucous membrane
Forms vestibular fold
Protects vocal ligaments
helps close the larynx during swallowing to prevent aspiration

Question 2

What are the vocal ligaments ?

Answer 2

Attach to;
- Internal aspect of Thyroid in midline
- Vocal processes of Arytenoids
Help form true vocal folds

Question 3

Describe the movements of the larynx:

Answer 3

Valsalva manoeuvre - forced expiratory effort against closed vocal folds or closed mouth & nose

Phonation - vibration of vocal ligaments as air passes through rima glottidis allows sound production

Breathing

Prevent entry of food/liquid

Extrinsic and intrinsic muscles move the larynx

Question 4

Describe the cricothyroid muscle

Answer 4

Tilts thyroid anteriorly
Connects cricoid cartilage to thyroid cartilage

2 aspects;
Pars recta - vertical part that tilts the thyroid cartilage downward
Pars obliqua - oblique part that slides the thyroid cartilage forward

Stretching the vocal ligaments increases the pitch of the voice

Innervated by superior laryngeal nerve

Question 5

Describe the Cricoarytenoid muscles:

Answer 5

Posterior cricoarytenoid;
- originates from the posterior surface of the cricoid cartilage
- inserts onto the muscular process of the arytenoid cartilage
- innervated by the recurrent laryngeal nerve
- abducts vocal folds

Lateral cricoarytenoid;
- originates from lateral surface of cricoid
- inserts muscular process of arytenoid cartilage
- innervated by recurrent laryngeal nerve
- adducts vocal folds

Question 6

Describe the Interarytenoids:

Answer 6

Oblique and transverse aspects
Join the arytenoids together
Adduct Arytenoids closing posterior part of rima glottidis
innervated by the recurrent laryngeal nerve

Question 7

Describe the vocalis:

Answer 7

Attaches along the length of the vocal ligament & modulates its tension
Forms part of the thyroarytenoid muscle
Innervated by the recurrent laryngeal nerve
Extends from inner thyroid cartilage to arytenoid cartilage

Question 8

Describe the Thyroarytenoid

Answer 8

Pulls thyroid & arytenoids closer together relaxing vocal ligament & reducing pitch
innervated by the recurrent laryngeal nerve
paired intrinsic muscle

Question 9

Describe the Aryepiglotticus:

Answer 9

pulls epiglottis inferiorly over laryngeal inlet during swallowing

Question 10

Describe the thyroid gland

Answer 10

Endocrine gland
Located inferior to thyroid cartilage and deep to infrahyoid muscles

Secretes;
- thyroid hormones regulating metabolism & growth
- calcitonin, decreases serum calcium

Left & Right Lobes connected by a narrow isthmus

Some people have a
pyramidal lobe
extending superiorly

4 Parathyroid glands are associated with & lie posteriorly to the thyroid gland
Secretes: Parathyroid hormone (increases serum calcium)

Question 11

Describe the structures entering the pharynx

Answer 11

Superior constrictor;
- Levator veli palatine
- Eustachian tube

Middle constrictor;
- Stylopharyngeus
- Glossopharyngeal nerve

Inferior constrictor;
- Internal laryngeal nerve
- Superior laryngeal vessels

Oesophagus;
- Recurrent laryngeal nerve
- Inferior laryngeal vessels

Question 12

What is Goiter and its causes ?

Answer 12

Enlarged thyroid gland

Causes;
- iodine deficiency, needed for thyroid hormone production so thyroid enlarges to increase production
- autoimmune disease (Grave’s) that damage thyroid
- Benign or Malignant tumours

Question 13

What are the extrinsic supra hyoid muscles ?

Answer 13

Digastric
Mylohyoid
Stylohyoid
Geniohyoid

Elevate hyoid/larynx

Question 14

What are the extrinsic Infrahyoid muscles ?

Answer 14

Omohyoid
Sternohyoid
Sternothyroid
Thyrohyoid

Depress hyoid/larynx

Question 15

Describe the nervous innervation to the larynx:

Answer 15

Innervated by branches of the vagus nerve (cranial nerve X), which provides motor and sensory innervation through the superior laryngeal nerve and recurrent laryngeal nerve, renamed as the inferior laryngeal nerve upon entering the larynx

Question 16

Describe the superior laryngeal nerves;

Answer 16

Internal laryngeal nerve;
- pierce the thyrohyoid membrane
- supply sensation to the laryngeal mucosa above the true vocal folds

External laryngeal nerve;
- Motor innervation to the cricothyroid muscle
- runs inferiorly

Question 17

Describe the recurrent laryngeal nerve;

Answer 17

Loops under the arch of the aorta (left) or the right subclavian artery (right), then ascends lateral to the trachea.

Enters the larynx in the gap between the inferior pharyngeal constrictor muscle

change their name to the Inferior laryngeal nerves after they pass the cricothyroid joint

innervate the laryngeal mucosa inferior to the true folds & all intrinsic laryngeal muscles except cricothyroid