Lecture 6 - Upper Airways

Question 1

What is the nasopharynx?

Answer 1

Region of pharynx dorsal to the soft palate

Auditory tubes open into nasopharynx

Question 2

How can an animal breathe whilst chewing?

Answer 2

• presence of palate allows breathing whilst chewing without aspiration of food

Question 3

What is the normal position of the soft palate during

Answer 3

Free edge of sp rostral to epiglottis
Soft palate v long in horse, hang beneath epiglottis = horse unable to breathe through mouth
Soft palate rest over epiglottis in bracheocephlic dogs

Soft palate raised during deglutition = stop food entering nasopharynx

Question 4

What is the function of auditory tubes and where do they lead from?

Answer 4

Equitation of pressure b/w middle ear cavity and external environment

Lead from middle ear cavity to open into lateral wall of nasopharynx
–> entrance opens during swallowing

Question 5

what are guttural pouches, what species are they found in and where are the anatomical positions of the guttural pouches?

Answer 5

Only in horses
Air filled diverticula of auditory tubes
Paired structure (2) meet in the mid line ventrally and separated by rectus capitus
1 = medial to mandible between skull and atlas dorsally
2 = b/w pharynx and proximal oesophagus ventrally

Question 6

What facial nerves, artery and lymph nodes are associated with the guttural pouches

Answer 6

Facial - CNVII
Glossopharyngeal - CNIX
Vagal - CNX
Accessory - CNIX
Hypoglossal - CNXII
And sympathetic trunk 
Internal carotid artery 
Medial retropharyngeal lymph nodes

Question 7

What is the function of the guttural pouches

Answer 7

Function unknown
Possibly: buffering pressure changes around middle ear
Cooling of blood to brain

Question 8

Where to the guttural pouches drain?

Answer 8

Drain via auditory tubes into nasopharynx

Question 9

What is the surgical approach to get to a guttural pouch?

Answer 9

Through viborgs triangle
Causal border of mandible
Sternocephslicus tendon
Linguofacial vein

Question 10

Describe the wall and suspension of the larynx

Answer 10

Wall formed by laryngeal cartilage and muscles
Lined by mucous membranes
Suspended from skull by hyoid apparatus

Question 11

What is the function of the larynx?

Answer 11

Connection between pharynx and trachea
Protection of the resp tract - closure during swallowing, sensory innervation (coughing reflex)
Vocalisation - vocal and vestibular folds
X2 components 1.phonation, 2.articulation

Question 12

What are the unpaired laryngeal cartilages?

Answer 12

Epiglottis
Thyroid
Cricoid

Question 13

What is the paired laryngeal cartilage?

Answer 13

Arytenoid

Question 14

what are the two major processes on the arytenoid cartilage?

Answer 14

vocal process - vocal folds

muscular process - cricoarytenoideus dorsals and cricoarytenoideus lateralis

Question 15

what is the function of movement of the arytenoid cartilages

Answer 15

responsible for closure of larynx

Question 16

what cartilage is the arytenoid cartilage composed of

Answer 16

part hyaline

part elastic

Question 17

describe the anatomical location of the arytenoid cartilage

Answer 17

medial to thyroid cartilages dorsally

caudal aspect articulates with rostral margin of cricoid

Question 18

describe the anatomical location of the cricoid cartilage

Answer 18

enlarged dorsally to form roof of larynx
forms a ring
caudal and partly medial to thyroid cartilage

Question 19

what cartilage is the cricoid cartilage composed of?

Answer 19

hyaline cartialge

Question 20

what is the epiglottis cartilage composed of, where is it positioned anatomically?

Answer 20

composed of elastic cartilage

most rostral

Question 21

what is the thyroid cartilage composed of and what boarder of the larynx does it form?

Answer 21

hyaline cartilage

form floor of the larynx

Question 22

what are the 5 laryngeal cavities

Answer 22

laryngeal vestibule
glottis
vocal fold
vestibular fold 
laryngeal ventricle

Question 23

what is the laryngeal vestibule?

Answer 23

open rostral part of larynx

Question 24

where is the glottis?

Answer 24

where the lumen narrows at the caudal end of the laryngeal vestibule.

Question 25

what muscle is the vocal folds composed of?

Answer 25

m. vocalis and mucosal covering

Question 26

what does the position of the vocal folds control?

Answer 26

the diameter of the glottis

Question 27

how does phonation occur?

Answer 27

air passing over vocal folds

Question 28

where is the vestibular fold located?

Answer 28

parallel to vocal folds - more rostral

Question 29

what is the larygenal ventricle?

Answer 29

pocket of mouse between vestibular and vocal folds (particularly deep in horses)

Question 30

what are the extrinsic muscles controlling the larynx?

Answer 30

pharyngeal constrictors - forming walls and roof of pharynx
muscles that move the larynx:
- throhyoideus
- sternothyroideus - draws larynx caudally
- hyoepiglotticus - draw ventrally

Question 31

what are the intrinsic muscles that move the cartilages relative to each other?

Answer 31

cricothyroideus - moves cricoid cartilage dorsally,tensing vocal folds
cricoarytenoideus dorsalis - abduct vocal folds
thyroarytenoideus - composed of m. vocals, m.ventricularis
arytenoideus transversus

Question 32

how is the larynx innervated?

Answer 32

vagus nerve CNX - provides sensory intro to larynx and motor innervation to all INTRINSIC MUSCLES OF larynx

Question 33

what does the cranial laryngeal muscle innervate?

Answer 33

motor to cricothyroideus

sensory to mucosa cranial to the vocal folds

Question 34

what does the caudal laryngeal nerve innervate?

Answer 34

motor to all intrinsic muscles except cricothyroideus
sensory to mucosa caudal to the vocal folds
damage to caudal laryngeal nerve = v serious

Question 35

describe the larynx in birds

Answer 35

• not used for vocalisation
• occupies laryngeal mound on floor of pharynx
• no epiglottis only cricoid and arytenoid cartilages
• glottis formed by arytenoids, no vocal folds.
  glottis closed by reflex action during swallowing