Lecture 33: Pharynx-Larynx Flashcards
Larynx: definition, articulates with, location
Structure at end of cranial end of respiratory system
Complex of several cartilages
Articulates with temporal bone via hyoid apparatus
Developmental origin of larynx and bronchial tree (and effect on anatomical relationship with another structure)
Offshoots of digestive tract
Retain relationship with pharynx
3 functions of larynx
Protection/isolation from digestive tract
Control of pulmonary air pressure (and intra thoracic and intra abdominal pressures)
Focalization
4 main cartilages of larynx
Epiglottis
Artyenoid
Thyroid
Cricoid
Which laryngeal cartilage is paired
arytenoid
Which laryngeal cartilages are unpaired
Epiglottis
Thyroid
Cricoid
Epiglottis: definition, location
Leaf shaped cartilage that extends from larynx to position caudal to last 1/3 of tongue
Which part of epiglottis articulates with thyroid cartilage on ventral midline
Stalk
Thyroid cartilage is composed of (2)
2 broad laminae fused ventrally but open dorsally = cranial and caudal horns
Cranial horn of thyroid cartilage articulates with
Thyrohyoid element of hyoid
Caudal horn of thyroid cartilage articulates with
Cricoid cartilage
Cricoid cartilage: definition, articulates with
Complete ring of cartilage with broad dorsal lamina
Articulates with thyroid cartilage at junction of lamina and vertebral arch = Cricothyroid joint
Arytenoid cartilage: definition, location, articulates with
Irregularly shaped cartilages with smaller fused cartilages
Articulates with cricoid cartilage on either side of cranial/Rostral edge of lamina
Within space bounded by thyroid cartilage
What type of joint exists between cricoid and each arytenoid cartilage
Synovial
What 3 movements are permitted at synovial joint between cricoid and arytenoid cartilages
Rotation around axis from cricoid to arytenoid
Medial lateral sliding
Limited dorsal ventral sliding
2 processes (muscle attachments) important for arytenoid functions
Muscular process
Vocal process
2 ligaments of larynx
Vestibular
Vocal
Vestibular ligament: location, function
Caudal edge of membrane that connects lateral sides of epiglottis to cranial end of arytenoid
Vocal ligament: location, function
Cranial edge of membrane that connects cricoid, thyroid and vocal processes of arytenoid
Vestibular fold definition
Vestibular ligament + overlying mucosa
Vocal fold
Vocal ligament + overlying mucosa
laryngeal ventricle
Pocket of mucosa formed between vestibular and vocal folds
What happens if you add mucosa layer to vestibular/vocal ligaments
Become folds
Only Laryngeal muscle that is visible external to larynx
Cricothyroideus
Cricothryoideus: function
Causes thyroid cartilage to rotate at cricothyroid joint
4 possible effects of laryngeal muscles on vocal folds
Adduction
Abduction
Lengthening
Shortening
adduction of vocal folds
Bring folds closer together to restrict airflow or produce phonation
Abduction of vocal folds
Separating folds to increase airflow
Lengthening of vocal folds
Tightens folds to raise pitch of sound produced
Shortening of vocal folds
Loosens folds to lower pitch of sound produced
2 ways to adduct vocal folds
Sliding arytenoid cartilages together
Pull muscular process of arytenoid ventrally
How to abduct vocal folds
Pull muscular process of artyenoid dorsally
What is the only laryngeal muscle that abducts the vocal folds
Dorsal cricoarytenoid
Dorsal cricoarytenoid: OINA
O - dorsal lamina of cricoid cartilage
I - muscular process of arytenoid
N - caudal laryngeal nerve
A - abduct vocal folds to bring in more air
5 nerves of larynx
Cranial laryngeal
External laryngeal
Internal laryngeal
Recurrent laryngeal
Caudal laryngeal
First branch off vagus nerve
Cranial laryngeal
Cranial laryngeal nerve splits into (2)
External and internal laryngeal nerves
External laryngeal nerve: innervates
Motor to cricothryoideus
Internal laryngeal nerve innervates (and function)
SENSATION from larynx cranial to vocal folds
Includes hyper sensitive vestibular folds
2nd line of defense after epiglottis
Recurrent laryngeal nerve path
Cranially through neck to approach larynx caudally
Recurrent laryngeal nerve continues as (once entering what structure)
Caudal laryngeal
Larynx
Caudal laryngeal nerve innervates
Motor to all other muscles and sensation from caudal 1/2 of larynx
Cough reflex: function, how it works
Prevent objects from getting into trachea
When object touches vestibular fold —> vocal folds tightly addicted to prevent further passage —> cough to expel object from larynx
2 nerves involved in cough reflex (and their relationship)
Sensory from internal laryngeal nerve —> sends into to caudal laryngeal nerve which provides motor to coughing muscles
Left recurrent hemiplegia: species, cause, effects, intervention
Horses
Loss of function on left side of larynx
Impairment of respiration —> intolerance to exercise —> roaring = typical sound heard
Surgically repaired by fixing/tie back affected arytenoid out of the way
3 regions of pharynx
Nasopharynx
Oropharynx
Laryngeopharynx
Nasopharynx, oropharynx, laryngopharynx: locations
Nasopharynx = dorsal region of pharynx caudal to nasal cavity
Oropharynx = caudal to palatoglossal fold
Laryngopharynx = dorsal to larynx
Which pharynx region has important communication with middle ear cavity via auditory tube
Nasopharynx
2 groups of pharyngeal muscles
Pharyngeal constrictors
Pharyngeal movers
3 pharyngeal constrictors
Hyopharyngeus
Thyropharyngeus
Cricopharyngeus
Pharyngeal constrictors: insertion and action
I - dorsal midline connective tissue line (raphe)
A - produce peristaltic movements that push food to esophagus
Hyopharyngeus: origin
Thyrohyoid and ceratohyoid elements of hyoid
Thyropharyngeus: origin
Lateral side of thyroid lamina
Cricopharyngeus: origin
Lateral aspect of ventral arch of cricoid
Most caudal
3 pharyngeal movers
Pterygopharyngeus
Stylopharyngeus
Palatopharyngeus
Pharyngeal movers: action
Pull pharynx into position to begin swelling —> shifted toward oral cavity for more space
Innervation of all 3 pharyngeal constrictors + pterygopharyngeus + Palatopharyngeus
Vagus
Innervation exception: pharyngeal muscles
Stylopharyngeus = glossopharyngeal
Pterygopharyngeus origin
Pterygoid hammulus
Stylopharyngeus: origin, innervation
Stylohyoid
CN IX
Palatopharyngeus origin
Soft palate
Major blood supply to pharynx
Ascending pharyngeal artery
Ascending pharyngeal artery: parent artery, path, what it Anastamoses with in dogs
External carotid
Runs cranially to foramen lacerum
Anastomose with loop of internal carotid artery that protrudes from foramen lacerum
Alternative route of blood supply to cerebral arterial circle in ruminants (no internal carotid)
Ascending pharyngeal passes through foramen lacerum
2 cranial nerves that innervates pharynx and muscles
CN IX
CN X
Which cranial nerve contributes mostly sensory axons to pharyngeal plexus
CN IX
Which cranial nerve contributes mostly motor axons to pharyngeal plexus
CN X
Gag reflex: function, how it works
Prevents swallowing of unexpected food or foreign objects
Touching pharyngeal mucosa of oropharynx —> sensory innervation by CN IX triggers wave of pharyngeal contraction that runs from caudal to cranial —> expels object from pharynx
