Lecture 33: Pharynx-Larynx Flashcards by Morgan Reich

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

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Developmental origin of larynx and bronchial tree (and effect on anatomical relationship with another structure)

Offshoots of digestive tract
Retain relationship with pharynx

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3 functions of larynx

Protection/isolation from digestive tract
Control of pulmonary air pressure (and intra thoracic and intra abdominal pressures)
Focalization

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4 main cartilages of larynx

Epiglottis
Artyenoid
Thyroid
Cricoid

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Which laryngeal cartilage is paired

arytenoid

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Which laryngeal cartilages are unpaired

Epiglottis
Thyroid
Cricoid

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Epiglottis: definition, location

Leaf shaped cartilage that extends from larynx to position caudal to last 1/3 of tongue

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Which part of epiglottis articulates with thyroid cartilage on ventral midline

Stalk

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Thyroid cartilage is composed of (2)

2 broad laminae fused ventrally but open dorsally = cranial and caudal horns

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Cranial horn of thyroid cartilage articulates with

Thyrohyoid element of hyoid

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Caudal horn of thyroid cartilage articulates with

Cricoid cartilage

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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

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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

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What type of joint exists between cricoid and each arytenoid cartilage

Synovial

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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

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2 processes (muscle attachments) important for arytenoid functions

Muscular process
Vocal process

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2 ligaments of larynx

Vestibular
Vocal

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Vestibular ligament: location, function

Caudal edge of membrane that connects lateral sides of epiglottis to cranial end of arytenoid

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Vocal ligament: location, function

Cranial edge of membrane that connects cricoid, thyroid and vocal processes of arytenoid

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Vestibular fold definition

Vestibular ligament + overlying mucosa

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Vocal fold

Vocal ligament + overlying mucosa

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laryngeal ventricle

Pocket of mucosa formed between vestibular and vocal folds

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What happens if you add mucosa layer to vestibular/vocal ligaments

Become folds

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Only Laryngeal muscle that is visible external to larynx

Cricothyroideus

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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