Lecutre 33: Pharynx and Larynx Flashcards
What structure is located at the cranial end of the respiratory system and is composed of several cartilages
Larynx
How does the larynx articulate to temporal bone
Via hyoid apparatus (tympanohyoid cartilages connect stylohyoid)
Developmentally the larynx is an off shoot of what
Digestive tract as they retain relationship with pharynx
What are some important functions of the larynx
Protection/isolation of airway from digestive tract, control of pulmonary air pressure and by extension intra thoracic and intra abdominal pressures, vocalization
What are the 4 cartilages of the larynx
Epiglottis, arytenoid, thyroid, cricoid
Which cartilage is paired
Arytenoid
Which cartilage has a leaf shape, extends from the larynx to a position caudal to the caudal third of the tongue
Epiglottis
What is the stalk of the epiglottis
Articulates with they thyroid cartilage on the ventral midline
Which cartilage is composed of two broad laminae fused ventrally but open dorsally and contain a cranial and caudal horn
Thyroid cartilage
What does the cranial horn of the thyroid cartilage articulate with
Thyrohyoid element of the hyoid apparatus
What does the caudal horn of the thyroid cartilage articulate with
Cricoid cartilage
What cartilage of the larynx contains a complete ring of cartilage with a broad dorsal lamina, contains a facet for articulation with thyroid cartilage
Cricoid cartilage
What cartilage of the larynx is irregularly shaped, articulates with cricoid cartilage on either side of rostral edge of lamina
Arytenoid cartilage
What type of joint is between the cricoid and arytenoid cartilage
Synovial
The synovial joint between the cricoid and arytenoid cartilage is very loose and permits what types of movements
Rotation, medial-lateral sliding, limited dorsal ventral sliding
What two processes provide important function to the arytenoid
Muscular process and vocal process
What process of the arytenoid cartilage is laterally directed
Muscular process
What process of the arytenoid is directed ventrally
Vocal process
What two ligaments connect the cartilages of the larynx together
Vestibular ligament and vocal ligament
Which ligament of the larynx is on the caudal edge of the membrane that connects the lateral sides of the epiglottis to the cranial end of the arytenoid
Vestibular ligament
What ligament of the larynx is on the cranial edge of the membrane that connects the cricoid, thyroid, and vocal process of the arytenoid
Vocal ligament
What is the vestibular fold
Contains the vestibular ligament plus overlying mucosa
What is the vocal fold
Contains the vocal ligament and overlying mucosa
What is the laryngeal ventricle
Pocket of mucosa formed between the vestibular and vocal folds
What muscle is visible to the external larynx
Cricothyroideus
What is the function of the cricothyroideus
Causes the thyroid cartilage to rotate at the cricothyroid joint
What are the four basic effects of the laryngeal muscles on vocal folds
Addiction, abduction, lengthening, shortening
What does the action of adduction of laryngeal muscles result in
Brings vocal folds closer together to restrict airflow to produce phonation
What does abduction of the laryngeal muscles result in
Separates vocal folds to increase airflow
What does lengthening of the laryngeal muscles result in
Tightens them to raise the pitch of the sound produced
What does shortening of the laryngeal muscles result in
Loosens them to lower the pitch of sound produced
How does the orientation of the arytenoid cartilages and muscular process change during adduction of the vocal folds
Slides the arytenoid cartilages together and pulls the muscular process of the arytenoid ventrally
How does the orientation of the arytenoid cartilages and muscular process change during abduction of the vocal folds
Pull the muscular process of the arytenoid dorsally and slides arytenoid cartilages away from each other
OINA for dorsal cricoarytenoid
O: dorsal lamina of cricoid cartilage
I: muscular process of the arytenoid
N: caudal laryngeal nerve
A: ONLY muscles that abducts the vocal folds
What are the 5 main nerves of the larynx
Cranial laryngeal, external laryngeal, internal laryngeal, recurrent laryngeal, and caudal laryngeal
What nerve is a branch off the vagus nerve and gives off the internal and external laryngeal nerves
Cranial laryngeal nerve
What nerve provides motor to the cricoid
External laryngeal nerve
What nerve provides sensation from the larynx cranial to the vocal folds including the hypersensitive vestibular folds
Internal laryngeal nerve
What nerve runs cranially throughout the neck to approach the larynx caudally
Recurrent laryngeal nerve
What nerve is a terminal branch of the recurrent laryngeal nerve carrying motor to all other muscles of the larynx and sensation from the caudal half of the larynx
Caudal laryngeal nerve
What is the cough reflex
Prevents objects from getting into trachea, when an object hits the vestibular fold the vocal folds are tightly adducted to prevent further passage
What nerves are involved in the cough reflex
Internal laryngeal and caudal laryngeal nerve
What nerve provides motor and what nerve provides sensation in the cough reflex
Internal laryngeal provides sensation and caudal laryngeal provides motor to expel object
Left recurrent Hemiplegia, a common neuropathy in horses can result in what
Compromised function of the cricoarytenoid muscles and loss of function on the left side
Results in impairment to respiration and produces “roaring sound”
Congenital in 3-5% of thoroughbreds
What are the three sections of the pharynx
Nasopharynx, oropharynx and laryngopharynx
What pharynx region is dorsal to the pharynx and caudal to nasal cavity
Nasopharynx
What region of the pharynx is caudal to the palatoglossal fold
Oropharynx
What pharynx region is dorsal to larynx
Laryngopharynx
The auditory tube provides important communication between what two structures
Nasopharynx and middle ear cavity
What are the important gutters on either side of the laryngeal opening
Piriform recess
What are the two functional groups of pharyngeal muscles
Pharyngeal constrictors and pharyngeal movers
Where do all pharyngeal constrictors insert
Dorsal midline connective tissue line (raphe)
What is the function of the pharyngeal constrictors
Produce peristaltic movements that push food to the esophagus
Where do all pharyngeal movers originate
Outside the pharyngeal wall and pass into the pharynx
What nerve innervates all pharyngeal muscles (except 1)
Vagus
What 3 muscles are pharyngeal constrictors
Hyopharyngeus, thyropharyngeus, cricopharyngeus
OINA for Hyopharyngeus
O: thyrohyoid and ceratohyoid elements of hyoid apparatus
I: dorsal midline CT (raphe)
N: vagus
A: produce peristaltic movements that push food to the esophagus
OINA for thyropharyngeus
O: lateral side of the thyroid lamina
I: dorsal midline CT (raphe)
N: vagus
A: produce peristaltic movement that push food to esophagus
OINA for cricopharyngeus
O: originate from the pterygoid hammulus
I: midline raphe
N: vagus
A: peristaltic movement that push food to esophagus
OINA for stylopharyngeus
O: stylohyoid
I: pharynx
N: GLOSSOPHARYNGEAL
A: put pharynx into position to begin swallowing
What artery provides the major blood supply to the pharynx
Ascending pharyngeal artery
What does the ascending pharyngeal artery branch off of
External carotid artery and runs cranially into foramen lacerum
In dogs, what does the ascending pharyngeal artery anastomose with
Loop of internal carotid artery that protrudes from foramen lacerum
In animals without an internal carotid artery (ex: cows) where does the ascending pharyngeal artery go
Passes through the foramen lacerum ands is one possible route of blood supply to cerebral arterial circle
What two cranial nerves contribute to the plexus that innervates the pharynx and its muscles
Glossopharyngeal (CN IX) and vagus (CN X)
Which cranial nerve contributes mostly sensory axons to pharyngeal plexus
Glossopharyngeal
Which cranial nerve contributes mostly motor axons to pharyngeal plexus
Vagus
The gag reflex prevents swallowing of unexpected food or foreign objects, describe the steps and players involved
Touching of the pharyngeal mucosa of oropharynx which is innervated by glossopharyngeal , which triggers a wave of pharyngeal contraction that runs from caudal to cranial and expels the object from the pharynx
