The larynx and hyoid apparatus

Question 1

What are the functions of the larynx

Answer 1

• Voice Box
• connection of nasopharynx and trachea
• breathing
• Protection of lower airway
• swallowing

Question 2

Describe the location of the larynx

Answer 2

Suspended by hyoid bones
Ventral to laryngopharynx
Caudal to tongue

Question 3

What is the hyoid apparatus

Answer 3

Bones which hold larynx in place

Question 4

Name the bones of the hyoid apparatus

Answer 4

Tympanohyoid 
Stylohyoid
Thyrohyoid
Basihyoid
Ceratohyoid
Epihyoid

Question 5

What is different about the stylohyoid bone in a horse

Answer 5

A lot longer in the horse

Less flexible- keeps it in place

Question 6

Name the different cartilages of the larynx

Answer 6

Hyaline:
- Thyroid= U-shaped 
- Cricoid = signet ring 
- Paired arytenoids= triangular 
Elastic:
- Epiglottis= leaf shaped

Question 7

What type of mucosa line the larynx

Answer 7

• Strtified squamous at the entrance (epiglottis)

- Pseudostratified ciliated in other areas

Question 8

What 3 types of structures connect the larynx cartilages to each other and to the trachea and hyoid bones

Answer 8

• Joints (cartilaginous or synovial)
• Collagenous and elastic ligaments
• Straited musculature

Question 9

What are the 2 important synovial joints in the larynx

Answer 9

• Cricoarytenoid joint

- Cricothyroid joint

Question 10

What does the Cricoarytenoid joint of the larynx allow

Answer 10

Allows rotation about both sagittal and transverse axis as well as sliding movements that bring the 2 arytenoid cartilages together or carry them farther apart

Question 11

What does the Cricothyroid joint of the larynx allow

Answer 11

allows rotation about the transverse axis

Question 12

What are the 2 ligaments in the larynx that move when the arytenoids move

Answer 12

• Vestibular ligament / fold

- Vocal ligament / fold

Question 13

Where are the intrinsic muscles of the larynx located and what are they involved in

Answer 13

• Located between the laryngeal cartilages

- Involved in respiration and phonation

Question 14

Where are the extrinsic muscles of the larynx located and what are they involved in

Answer 14

Connect the larynx to hyoid bones, pharynx and sternum

Involved in swallowing

Question 15

What is the only muscle that widens the glottis- what innervates it

Answer 15

Cricoarytenoideus dorsalis- innervated by the recurrent laryngeal nerve

Question 16

What are the 2 most important muscles that narrow/close the glottis

Answer 16

• Cricothyroideus

- Cricoarytenoideus lateralis

Question 17

What does the cranial laryngeal nerve innervate in the larynx

Answer 17

• Sensory innervation of the laryngeal mucous membrane

- Motor innervation of the cricothyroideus

Question 18

What does the recurrent laryngeal nerve innervate in the larynx

Answer 18

Innervation of all laryngeal muscles except the cricothyroideus muscle

Question 19

How is the laryngeal entrance protected upon swallowing

Answer 19

• Larynx is drawn rostrally and moved dorsally
• Epiglottis tilts backwards and partially covers the laryngeal entrance
• Arytenoid cartilages approach each other
• Main seal is the closure of the glottis

Question 20

What are 4 situations in which the glottis is closed

Answer 20

• During swallowing
• To allow pressure to build up before coughing
• During straining
• Closure is important during eructation and rumination in ruminants

Question 21

What is idiopathic laryngeal hemiplegia more commonly known as

Answer 21

Roaring

Flaccid arytenoid cartilage is sucked into the laryngeal lumen

Question 22

What structure is responsible for sound production in birds

Answer 22

Syrinx