Week 2 Respiratory Flashcards
Define the nasopharynx. Name one significance
Region of the pharynx dorsal to the soft palate. Auditory tubes open into the nasopharynx (lateral wall)
What is the significance of the soft palate?
Allows animal to breathe while chewing without aspiration of food. Also, stops food from entering the nasopharnynx as it raises during deglutition (swallowing).
What is the normal position of the soft palate in most species?
Free edge rostral to epiglottis in most species
Who has a long soft palate, what does this cause?
Horses and brachycephalic dogs- rests over or hangs down beneath epiglottis- horses unable to breathe through mouth- sometimes displaced over epiglottis during horses exercising
What does the auditory tubes do?
Allow equilization of pressure between middle ear cavity and external environment
When does the auditory tube close and open?
Normally closed but opens during swallowing
What are guttural pouches?
Air filled diverticula of auditory tubes, thin-walled, lined with respiratory mucosa
Where are the guttural pouches separated by?
Rectus capitis ventralis dorsally. Moulded over stylohyoid bone which divides each pouch incompletely into lateral and medial components.
What nerves are guttural pouches associated with?
Facial (CN VII, 7), glossopharyngeal (CNIX 9), vagal (CNX), accessory (CNXI), and hypoglossal (CNXII)
How do guttural pouches drain?
Via auditory tubes into nasopharynx
What is the surgical approach through Viborg’s triangle?
Caudal border of mandible
Sternocephalicus tendon
Linguofacial vein
What are the larynx’s walls formed by?
Laryngeal cartilage and muscle
What is the larynx lined by?
Mucous membrane
What is the larynx suspended from skull by?
Hyoid apparatus
What is the function of the larynx?
Connection between pharynx and trachea, protection of respiratory tract (closure during swallowing), sensory innervation- coughing reflex, vocalization (vocal and vestibular folds)– phonation and articulation
What are the unpaired laryngeal cartilages?
Epilgottis, thyroid, and cricoid
What is the paired laryngeal cartilage?
Arytenoid
What kind of cartilage makes up the arytenoid cartilage?
Part hyaline, part elastic
At what joint and what is the movement of the arytenoids responsible for?
Cricoarytenoid joint responsible for the closure of the larynx
Describe the cricoid cartilage
Forms ring, enlarged dorsally to form roof of larynx, caudal and partly medial to thryoid cartilage, hyaline cartilage
Describe the epiglottis
Most rostral, elastic cartilage
Describe thyroid cartilage
Largest, two lateral planes (walls of larynx) meet ventrally to form floor of larynx, most rostral part thickened (adam’s apple), hyaline cartilage
What is the laryngeal vestibule?
Open rostral part of larynx
What is the glottis?
lumen narrows at caudal limit of vestibule- comprised of arytenoid cartilages and vocal folds
What are the vocal folds?
comprised of m. vocalis and mucosal covering- runs from vocal process of arytenoid cartilage to floor of thyroid cartilage, position dependent on position of arytenoids, position controls diameter of glottis, air passing over vocal folds leads to phonation
What is the vestibular fold?
Parallel to vocal fold but more rostral
What is the laryngeal ventricle?
Pocket of mucosa between vestibular and vocal folds (particularly deep in horses)
What are the muscles that move the larynx?
Thyrohyoideus, sternothyroideus (draws larynx caudally), hyoepiglotticus (draws epiglottis ventrally)
What does the cricothyroideus do?
Moves cricoid cartilage (and arytenoid with it) dorsally thus tensing vocal folds
What does the cricoarytenoideus dorsalis do?
Abducts vocal folds
What does the cricoarytendoideus lateralis do?
Adducts vocal folds
What is the thyroarytenoideus composed of?
M. vocalis and m. ventricularis (occupy vocal and vestibular folds)
What innervates the laryngeal cavity?
Vagus nerve (branches of- CNX) sensory innervation to larynx and motor innervation to all intrinsic muscles of the larynx, cranial laryngeal nerve (motor to cricothyroideus/ sensory to mucosa cranial to vocal folds), caudal laryngeal nerve from recurrent laryngeal nerve (motor to all intrinsic muscles except cricothyroideus/ sensory to mucosa caudal to vocal folds/ damage to caudal laryngeal nerve has serious clinical implications
Where is the trachea located in the neck?
Ventrally
Where does the trachea bifurcate into two principal bronchi?
At the level of the 4th and 5th thoracic vertebrae
What species has complete rings on the trachea?
Birds
What kind of cartilage is in the trachea?
Hyaline
What muscle forms the roof of the trachea?
Trachealis (smooth muscle)
What are annular ligaments?
Connective tissue joining adjacent rings