Chapter 101 - Larynx

Question 1

Where do the cranial laryngeal nerves and arteries pass though?

Answer 1

Through the rostral thyroid notches.

Question 2

The extrinsic muscles of the larynx constrict the caudal part of the pharynx. Name them?

Answer 2

Cricopharyngeus and thyropharyngeus

Question 3

Where does cricoarytenoideus dorsalis insert?

Answer 3

On the muscular process of the arytenoid cartilage which is lateral to the cricoarytenoid articulation.

Question 4

Thyropharyngeus - function, insertion and innervation?

Answer 4

• Covers the outside of the larynx, extends from lateral surface of thyroid cartilage and inserts on the median raphe of dorsal pharynx
• innervated by glossopharyngeal and vagal nerves
• constrict caudal part of the pharynx

Question 5

Cricopharyngeus - function, insertion and innervation?

Answer 5

-caudal to the thyropharyngeus muscle - arising from the lateral surface of cricoid cartilage and inserting on medial raphe of pharynx
- on caudal margin some fibers blend with the esophagus
- innervated by glossopharyngeal and vagal nerves
- constrict caudal part of the pharynx

Question 6

What is the most important intrinsic muscle of the larynx?

Answer 6

Cricoarytenoideus dorsalis

Abducts the arytenoid cartilage to open the glottis.

Question 7

The intrinsic muscles are responsible for laryngeal function. What are the 6 intrinsic muscles of the larynx?

Answer 7

• CAD
• CAL
• Thyroarytenoideus
• Arytenoideus transversus
• Hyoepiglotticus
• Cricothyroideus

Question 8

What nerves innervate the larynx?

Answer 8

Cranial and caudal laryngeal nerves, which arise from the vagus.

The caudal laryngeal nerve is the terminal segment of the recurrent laryngeal nerve.

The cranial laryngeal has an internal branch that anastomoses with the caudal, and an external branch that is the afferent limb of the cough reflex.

Question 9

The caudal laryngeal nerve supplies all the intrinsic laryngeal muscles except for which muscle?

Answer 9

Cricothyroideus

Question 10

Which arteries are the primary blood supply to the larynx?

Answer 10

Cranial and caudal thyroid arteries.

Question 11

How does feline laryngeal anatomy differ from dogs?

Answer 11

• The arytenoid cartilages lack a cuneiform and corniculate process
• true aryepiglottic folds are absent
• vocal cords are thick and rounded
• ventricles are absent

Question 12

Name the (4) processes of the arytenoid cartilages:

Answer 12

• Cuneiform
• Corniculate
• Vocal
• Muscular

Question 13

What are three functions of the larynx?

Answer 13

Block laryngeal opening during swallowing
control airway resistance
voice production

Question 14

What are the three stages of laryngeal collapse?

Answer 14

• Stage I - Everted laryngeal saccules
• Stage II - Cuneiform process loses its rigidity and becomes medially displaced
• Stage III - Corniculate process collapse, resulting in loss of dorsal arch of rima glottidis

Question 15

What lymph nodes drain the larynx?

Answer 15

Medial retropharyngeal lymph nodes

Question 16

What is doxapram?

Answer 16

CNS stimulant which causes an increased respiratory rate and tidal volume. Used in laryngoscopy if respiration is weak/anesthesia too deep and need to verify normal function/lack thereof.

Question 17

Rapid narrowing and widening of the glottis by the laryngeal muscles and fast twitching of the diaphragm causes what in cats?

Answer 17

Purring (vibrations of respiratory air)

Question 18

Name the (6) cartilages of the larynx:

Answer 18

Epiglottic
Thyroid
Cricoid
Sesamoid
Interarytenoid
Arytenoid

Question 19

Pathway of the left caudal laryngeal nerve?

Answer 19

The left recurrent laryngeal nerve from the left vagus arches around the aorta, ascends along the trachea, and gives off the pararecurrent laryngeal nerve before terminating as the left caudal laryngeal nerve.

Question 20

Which intrinsic laryngeal muscle is solely responsible for arytenoid abduction during inspiration?

Answer 20

Cricoarytenoideus dorsalis — originates from dorsolateral cricoid and inserts on muscular process of arytenoid; opens glottis.

Question 21

Which nerve provides motor innervation to all intrinsic laryngeal muscles except the cricothyroideus?

Answer 21

Caudal laryngeal nerve (terminal recurrent laryngeal nerve).

Question 22

Which branch of the cranial laryngeal nerve provides motor innervation to the cricothyroideus muscle?

Answer 22

External branch of the cranial laryngeal nerve.

Question 23

Damage to the left recurrent laryngeal nerve most commonly occurs where due to its anatomic course?

Answer 23

As it arches around the aortic arch before ascending along the trachea.

Question 24

Which cartilage forms a complete ring and articulates synovially with both the thyroid and arytenoid cartilages?

Answer 24

Cricoid cartilage.

Question 25

Which arytenoid process serves as the insertion site for the cricoarytenoideus dorsalis muscle?

Answer 25

Muscular process of the arytenoid cartilage.

Question 26

What structure separates the ventricular and vocal folds and can evert in laryngeal disease?

Answer 26

Laryngeal ventricle (laryngeal saccule).

Question 27

Which intrinsic muscle relaxes the vocal cords by drawing the arytenoid cartilage downward?

Answer 27

Vocalis portion of the thyroarytenoideus muscle.

Question 28

Which intrinsic muscle increases vocal cord tension by pivoting the cricoid cartilage on the thyroid articulation?

Answer 28

Cricothyroideus muscle.

Question 29

Which extrinsic muscle constricts the caudal pharynx and is innervated by glossopharyngeal and vagal nerves?

Answer 29

Thyropharyngeus muscle.

Question 30

Which feline laryngeal structures are absent compared to dogs?

Answer 30

Cuneiform and corniculate processes; true ventricles/saccules.

Question 31

During swallowing, what coordinated movement prevents aspiration?

Answer 31

Cranial movement of larynx and hyoid apparatus positioning rima glottidis under epiglottis.

Question 32

What is the primary physiologic mechanism for decreasing airway resistance during inspiration?

Answer 32

Abduction of arytenoid cartilages widening the rima glottidis.

Question 33

Which cartilage is the largest laryngeal cartilage and forms lateral laminae?

Answer 33

Thyroid cartilage.

Question 34

Which nerve branch serves as the afferent limb of the cough reflex?

Answer 34

Internal branch of the cranial laryngeal nerve.

Question 35

Which blood vessels primarily supply the larynx?

Answer 35

Cranial and caudal thyroid arteries.

Question 36

Which lymph nodes receive lymphatic drainage from the larynx?

Answer 36

Medial retropharyngeal lymph nodes.

Question 37

Which intrinsic muscle assists with glottic constriction by inserting on the interarytenoid cartilage?

Answer 37

Arytenoideus transversus.

Question 38

Which feline physiologic mechanism explains purring?

Answer 38

Rapid narrowing/widening of glottis plus fast diaphragmatic contractions causing airflow vibration.

Question 39

What type of joint exists between cricoid–thyroid and cricoid–arytenoid articulations?

Answer 39

Synovial joints enclosed in articular capsules.