Lecture 31 - Pharynx and Larynx Flashcards
What are the larynx and bronchial tree developmentally related to?
Digestive tract - see this with the pharynx
What part of the larynx articulates with the temporal bone?
Hyoid apparatus
What are the three functions of the larynx?
Protection/isolation of the airway from the digestive tract
Control pulmonary air pressure
Vocalization
What are the four cartilages of the larynx?
Epiglottis - Arytenoid - Thyroid - Cricoid
What is the paired set of cartilages in the larynx?
Arytenoid
What is the positioning of the epiglottis?
Extends from the larynx to a position caudal third of the tongue
What does the stalk of the epiglottis do?
Articulates with the thyroid cartilage on ventral midline
What does the cranial horn of the thyroid cartilage articulate with?
Thyrohyoid element of the hyoid appratus
What does the caudal horn of the thyroid cartilage articulate with?
Cricoid cartilage
What function does the cricoid cartilage provide?
Facet for articulation with the thyroid cartilage at the junction of the lamina and ventral arch
What types of movements can the arytenoid cartilage do?
Rotation
Medial-lateral
Dorsal-ventral (limited)
What are the two processes of the arytenoids?
Muscular and vocal
What direction are the muscular process of the arytenoids directed?
Laterally
What way are the vocal processes directed?
Ventrally
What are the two membranes of the larynx?
Vestibular and Vocal
Where is the vestibular ligament located?
Caudal edge of a membrane connects lateral sides of the epiglottis to the cranial end of the arytenoid
Where are the vocal ligaments located?
Cranial edge of a membrane that connects the cricoid, thyroid, and vocal processes of the arytenoid
What is the action of the cricothyroideus m.?
Thyroid cartilage rotates at the cricothyroid joint
What are the four effects of the laryngeal muscles on the vocal folds?
Adduction - Abduction
Lengthening - Shortening
What does adduction of the vocal folds cause?
restricts airflow or produce phonation
What does abduction of the vocal folds cause?
Increase airflow
What does lengthening of the vocal folds cause?
Raise pitch of sound produced
What does shortening of the vocal folds cause?
Lower the pitch of the sound
What is the only muscle that abducts the vocal folds?
Dorsal Crucoarytenoid
Where does the dorsal cricoarytenoid articulate?
Dorsal lamina of cricoid cartilage
Where does the dorsal cricoarytenoid muscle insert?
Muscular process of the arytenoid
What nerve innervates the dorsal cricoarytenoid?
Caudal laryngeal n.
What occurs in regards to the muscles when abduction of teh vocal folds occur?
Pull muscular process of arytenoid dorsally
What are the five major nerves to the Larynx?
Cranial - External - Internal - Recurrent - Caudal
What does the cranial laryngeal nerve come off of?
Branch of the vagus nerve
What does the cranial laryngeal nerve give rise to?
External and internal laryngeal n.
What does the external laryngeal n. do?
Motor to the cricothyroid
What does the internal laryngeal nerve do?
Sensation from the larynx cranial to the vocal folds
Vestibular folds
Where is the recurrent laryngeal n.?
Runs cranially through the neck to approach larynx caudally
What does the caudal laryngeal n branch from?
Recurrent laryngeal n.
What does the laryngeal n. do?
Carry motor to all other muscles and sensation from caudal half of larynx
What is the function of the cough reflex?
Prevent objects from getting into the trachea
How is the cough reflex intiated?
Object touches vestibular fold
What happens when the cough reflex is initiated?
Vocal folds are tightly ADDucted to prevent further passage
What two nerves are involved in the cough reflex?
Internal and caudal laryngeal
What function does the internal laryngeal n. provide in the cough reflex?
Sensation from the larynx cranial to the vocal folds, senses the object
What happens in horses that causes problems with the dorsal cricoarytenoid muscle?
Left recurrent hemiplegia
What animal, specifically, does left recurrent hemiplegia occur in?
3-5% of thoroughbreds
What happens with left recurrent hemiplegia?
Impairment of respiration produces an intolerance to exercise
Roaring occurs
What is deglutition?
Swallowing
What structures are involved in swallowing?
Tongue - Palate - Pharynx
What function does the soft palate have in swallowing?
Elevates to close off the nasal cavity
What function does the pharynx have in swallowing?
Approaches oral cavity and widens to receive food
What ellicits peristalsis in swallowing?
Food making contact with the pharyngeal wall
What are the three regions of the pharynx?
Nasopharynx - Oropharynx - Laryngopharynx
Where is the oropharynx?
Caudal to the palatoglossal fold
What does the auditory tube do?
Connects middle ear to nasopharynx
What are the two muscle groups in regards to the pharynx?
Constrictors and movers
Where do the pharyngeal constrictors insert?
Dorsal midline connective tissue line
What do the pharyngeal constrictors do?
Produce peristaltic movements that push food to the esophagus
What do the pharyngeal movers do?
Put pharynx into position to begin swallowing
Where do the pharyngeal movers originate?
Put the pharynx into position to being swallowing
What are almost all the pharyngeal muscles innervated by?
CN X - vagus
Where do the pharyngeal movers originate?
Outside the pharyngeal wall and pass into the pharynx -
What are the pharyngeal constrictors?
Hyopharyngeus - Thyropharyngeus - Cricopharyngeus
Where does the hyopharyngeus originate?
On thyrohyoid and ceratohyoid elements of the hyoid apparatus
Where does the thyropharyngeus originate?
Originates on the lateral side of the thyroid lamina
Where does the cricopharyngeus originate?
On the lateral aspect of the ventral arch of the cricoid
What are the pharyngeal movers?
Pterygopharyngeus - Stylopharyngeus - Palatopharyngeus
Which mover is innervated by the Glossopharyngeal nerve?
Stylopharyngeus
Where does the pterygopharyngeus originate?
Pterygoid hammulus
Where does the stylopharyngeus originate?
Stylohyoid
What else does the stylopharyngeus do?
Pharyngeal dilator
What artery supplies most of the pharynx?
Ascending pharyngeal artery
What does the ascending pharyngeal artery come off of?
External carotid
What does the ascending pharyngeal artery anastomose with in dogs?
Internal carotid artery
Where does the internal carotid come from?
Foramen lacerum
What happens with the ascending pharyngeal artery in animals without internal carotid artery?
becomes a possible alternate route of blood supply to the cerebral arterial circle
What two cranial nerves contribute to the plexus of the pharynx?
Glossopharyngeal N.
– and –
Vagus N.
What nerves are part of the gag reflex?
CN IX - X
What is the function behind the gag reflex?
Prevents swallowing of unexpected food or foreign objects
What starts the gag reflex?
Touching the pharyngeal mucosa of oropharynx
What provides the sensory innervation to the oropharynx?
CN IX - Glossopharyngeal
What happens when the gag reflex is started?
Wave of pharyngeal contraction that runs caudal to crainal
What does the CN IX contribute to?
Mostly sensory oxons to the pharyngela plexus
What does the vagus nerve contribute to?
Motor axons to the pharyngeal plexus
