Exam 2 - Equine Upper Respiratory Anatomy, Function, & Diagnostics Flashcards
what nerve provides sensory to the face & mucosa?
trigeminal nerve - cn V
what nerve provides motor function to the muscles of facial expression?
facial nerve - cn VII
what is the action of the levator nasolabialis muscle?
lifts lips & nares up
what is the action of the dilator naris lateralis muscle?
pulls nares out to the side
what is the action of the transversus nasi muscle?
pulls nares up & forward
what anatomic structure defines the nasopharynx? how?
nasal septum
nasopharynx begins at the nasal septum & ends at the level of the ethmoid turbinates
the infraorbital canal runs between what 2 sinuses? is there any communication?
rostral maxillary sinus & ventral conchal sinus
rostral maxillary sinus communicates with the ventral conchal sinus over the infraorbital canal
what are the circled structures?
purple - rostral maxillary sinus
yellow - infraorbital canal
green - ventral conchal sinus
how does the dorsal conchal & frontal sinus communicate with the caudal maxillary sinus?
frontomaxillary aperture
what does the maxillary septum divide?
the rostral maxillary sinus from the caudal maxillary sinus
bulla of the maxillary septum walls off the little compartment dorsally
what is the direct opening between the frontal & caudal maxillary sinuses called?
frontomaxillary aperture
what is the name of the structure that is a natural opening of the maxillary sinuses into the nasal cavity through the middle meatus?
nasomaxillary opening
T/F: there is no direct communication between the frontal sinus & nasal cavity
true
what is included in the ‘big’ compartment of the paranasal sinuses of the horse?
dorsal conchal sinus
frontal sinus - frontomaxillary aperture - caudal maxillary
sphenopalatine
what is included in the ‘little’ compartment of the paranasal sinuses of the horse?
ventral conchal & rostral maxillary
label all:
orange, light blue, green, yellow, red, purple, & dark blue
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
what is the action of the intrinsic muscles of the nasopharynx?
supports the wall
dilation during respiration
contraction during swallowing
what is the action of the extrinsic muscles of the nasopharynx?
associated with the hyoid apparatus
indirectly maintains patency - laryngeal & oropharyngeal position
what defines the floor of the nasopharynx?
soft palate - tight seal with the epiglottis
what structures make up the nasopharynx?
intrinsic & extrinsic muscles
soft palate
salpingopharyngeal plicae
dorsopharyngeal recess
what is located in the medial compartment of the guttural pouches?
pharyngeal branch of the vagus n
cn 9-12
cervical sympathetic trunk
internal carotid a
what is located in the lateral compartment of the guttural pouches?
cn 7 & 8
external carotid artery - becomes maxillary artery
how do the paired arytenoids articulate with the cricoid?
corniculate process
muscular process
vocal process
what does they thyroid cartilage articulate with?
cricoid - cricothyroid membrane is palpable
what muscle is responsible for opening the larynx during breathing?
cricoarytenoideus dorsalis - opens arytenoids
what muscle is responsible for closing the larynx during swallowing?
cricoarytenoideus lateralis - closes arytenoids
what is the function of the extrinsic muscles of the larynx?
stabilize the hyoid apparatus & larynx
some function in rima glottis area
what is the neural input/output of the larynx?
internal & external branches of the cranial laryngeal n - branch of the vagus
recurrent laryngeal nerve - branch of the vagus
what is the structure of the trachea regarding the location of hyaline cartilage, smooth muscle, & annular ligaments?
hyaline cartilage rings ventrally
smooth muscle dorsally - stabilization during respiration & relaxation during swallowing
annular ligaments between rings
what are the general mechanics of normal respiration in a horse?
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
what is the formula for minute ventilation?
breath volume * respiratory rate
what is the minute ventilation of a horse at rest? at exercise?
at rest - 67 L/min
exercise - 1800 L/min
what is poiseulle’s law?
reduction of the radius by 1/2 increases the resistance by a factor of 16
how does the bernoulli effect work in horses?
makes everything want to collapse into the airway lumen
why not use sedation when doing upper airway diagnostics?
affects muscles & clouds clinical judgement
what are some differentials for right-sided RLN?
arytenoid chondritis
iatrogenic
4th brachial arch deficiency - fusion of cricothyroid
naturally occuring RLN
how can you differentiate between left & right RLN?
slap test & ultrasound evaluation
what are the disadvantages of using endoscopy for dynamic lesions?
up to 85% false negative rate
what are some indications for doing a dynamic endoscopy exam?
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)
when is CT useful in upper airway disease?
sinuses, teeth, ethmoids, & luminal laryngeal problems
when is MRI useful for evaluating upper airway disease?
intrinsic laryngeal musculature assessment
inhalation results in lower airway ______ & upper airway ______
expansion
collapse
