Exam 2 - Equine Upper Respiratory Anatomy, Function, & Diagnostics

Question 1

what nerve provides sensory to the face & mucosa?

Answer 1

trigeminal nerve - cn V

Question 2

what nerve provides motor function to the muscles of facial expression?

Answer 2

facial nerve - cn VII

Question 3

what is the action of the levator nasolabialis muscle?

Answer 3

lifts lips & nares up

Question 4

what is the action of the dilator naris lateralis muscle?

Answer 4

pulls nares out to the side

Question 5

what is the action of the transversus nasi muscle?

Answer 5

pulls nares up & forward

Question 6

what anatomic structure defines the nasopharynx? how?

Answer 6

nasal septum

nasopharynx begins at the nasal septum & ends at the level of the ethmoid turbinates

Question 7

the infraorbital canal runs between what 2 sinuses? is there any communication?

Answer 7

rostral maxillary sinus & ventral conchal sinus

rostral maxillary sinus communicates with the ventral conchal sinus over the infraorbital canal

Question 8

what are the circled structures?

Answer 8

purple - rostral maxillary sinus

yellow - infraorbital canal

green - ventral conchal sinus

Question 9

how does the dorsal conchal & frontal sinus communicate with the caudal maxillary sinus?

Answer 9

frontomaxillary aperture

Question 10

what does the maxillary septum divide?

Answer 10

the rostral maxillary sinus from the caudal maxillary sinus

bulla of the maxillary septum walls off the little compartment dorsally

Question 11

what is the direct opening between the frontal & caudal maxillary sinuses called?

Answer 11

frontomaxillary aperture

Question 12

what is the name of the structure that is a natural opening of the maxillary sinuses into the nasal cavity through the middle meatus?

Answer 12

nasomaxillary opening

Question 13

T/F: there is no direct communication between the frontal sinus & nasal cavity

Answer 13

true

Question 14

what is included in the ‘big’ compartment of the paranasal sinuses of the horse?

Answer 14

dorsal conchal sinus

frontal sinus - frontomaxillary aperture - caudal maxillary

sphenopalatine

Question 15

what is included in the ‘little’ compartment of the paranasal sinuses of the horse?

Answer 15

ventral conchal & rostral maxillary

Question 16

label all:

orange, light blue, green, yellow, red, purple, & dark blue

Answer 16

orange - rostral maxillary & ventral conchal

light blue - maxillary septum

yellow - caudal maxillary

dark blue - dorsal conchal

purple - frontal sinus

green - bulla & frontomaxillary aperture

red - sphenopalatine

Question 17

what is the action of the intrinsic muscles of the nasopharynx?

Answer 17

supports the wall

dilation during respiration

contraction during swallowing

Question 18

what is the action of the extrinsic muscles of the nasopharynx?

Answer 18

associated with the hyoid apparatus

indirectly maintains patency - laryngeal & oropharyngeal position

Question 19

what defines the floor of the nasopharynx?

Answer 19

soft palate - tight seal with the epiglottis

Question 20

what structures make up the nasopharynx?

Answer 20

intrinsic & extrinsic muscles

soft palate

salpingopharyngeal plicae

dorsopharyngeal recess

Question 21

what is located in the medial compartment of the guttural pouches?

Answer 21

pharyngeal branch of the vagus n

cn 9-12

cervical sympathetic trunk

internal carotid a

Question 22

what is located in the lateral compartment of the guttural pouches?

Answer 22

cn 7 & 8

external carotid artery - becomes maxillary artery

Question 23

how do the paired arytenoids articulate with the cricoid?

Answer 23

corniculate process

muscular process

vocal process

Question 24

what does they thyroid cartilage articulate with?

Answer 24

cricoid - cricothyroid membrane is palpable

Question 25

what muscle is responsible for opening the larynx during breathing?

Answer 25

cricoarytenoideus dorsalis - opens arytenoids

Question 26

what muscle is responsible for closing the larynx during swallowing?

Answer 26

cricoarytenoideus lateralis - closes arytenoids

Question 27

what is the function of the extrinsic muscles of the larynx?

Answer 27

stabilize the hyoid apparatus & larynx some function in rima glottis area

Question 28

what is the neural input/output of the larynx?

Answer 28

internal & external branches of the cranial laryngeal n - branch of the vagus recurrent laryngeal nerve - branch of the vagus

Question 29

what is the structure of the trachea regarding the location of hyaline cartilage, smooth muscle, & annular ligaments?

Answer 29

hyaline cartilage rings ventrally smooth muscle dorsally - stabilization during respiration & relaxation during swallowing annular ligaments between rings

Question 30

what are the general mechanics of normal respiration in a horse?

Answer 30

active expansion of the thorax lowers pressure within the airway tension of the upper airway provides dilation & stabilization air moves down its pressure gradient gas exchange occurs at the alveoli only passive exhalation with active contraction at the end

Question 31

what is the formula for minute ventilation?

Answer 31

breath volume * respiratory rate

Question 32

what is the minute ventilation of a horse at rest? at exercise?

Answer 32

at rest - 67 L/min exercise - 1800 L/min

Question 33

what is poiseulle's law?

Answer 33

reduction of the radius by 1/2 increases the resistance by a factor of 16

Question 34

how does the bernoulli effect work in horses?

Answer 34

makes everything want to collapse into the airway lumen

Question 35

why not use sedation when doing upper airway diagnostics?

Answer 35

affects muscles & clouds clinical judgement

Question 36

what are some differentials for right-sided RLN?

Answer 36

arytenoid chondritis iatrogenic 4th brachial arch deficiency - fusion of cricothyroid naturally occuring RLN

Question 37

how can you differentiate between left & right RLN?

Answer 37

slap test & ultrasound evaluation

Question 38

what are the disadvantages of using endoscopy for dynamic lesions?

Answer 38

up to 85% false negative rate

Question 39

what are some indications for doing a dynamic endoscopy exam?

Answer 39

problem is only present during exercise suspicion of UA disease but normal resting see something - lymphoid hyperplasia, diffuse or focal hyperemia, or grade 2 RLN poor performance work up PPE - respiratory noise heard during exam, high value animal doing high intensity work, or abnormal findings on physical exam (assymetrical slap test)

Question 40

when is CT useful in upper airway disease?

Answer 40

sinuses, teeth, ethmoids, & luminal laryngeal problems

Question 41

when is MRI useful for evaluating upper airway disease?

Answer 41

intrinsic laryngeal musculature assessment

Question 42

inhalation results in lower airway ______ & upper airway ______

Answer 42

expansion collapse