Larynx Flashcards
Where is the larynx?
Between the hyoid bone above, and trachea below
What vertebral level is the pharynx at?
C4-6
What are the functions of the larynx?
Ventilation
Airway protection
Allows us to cough
Production of sound
How is the larynx involved in ventilation?
Allow movement of air into and out of the lungs
How is the larynx involved in airway protection?
Preventing food and liquid that we swallow from entering the airway
Why is coughing important?
Important protective mechanism to expel rapidly any substances that have inadvertently found their way into the lower airways
What modifies the production of sound?
Pharynx Oral cavity Lips Teeth Tongue
What does the pharynx consist of?
Series of cartilages and bones
What is the structural framework of the larynx formed by?
Epiglottis
Thyroid cartilage
Cricoid cartilages
Arytenoid cartilages
What is the epiglottis?
A leaf shaped plate of fibroelastic cartilage
What is the function of the epiglottis?
Safety flap over larynx
What are the surfaces of the epiglottis?
Lingual
Underside
What epithelium does the lingual surface of the epiglottis have?
Stratified squamous epithelium
Why does the lingual surface of the epiglottis have stratified squamous epithelium?
Resistant to abrasion of bolus
What epithelium does the underside of the epiglottis have?
Columnar epithelium
What is the epiglottis attached to anteriorly?
Hyoid
What is the epiglottis attached to posteriorly?
Back of the thyroid cartilage
How is the epiglottis attached to the thyroid cartilage?
Thyroepiglottic ligament
What are the sides of the epiglottis attached to?
Arytenoids
How are the arytenoids attached to the sides of the epiglottis?
Aryepiglottic folds
What happens to the aryepiglottic folds?
Run backwards to form margins of entrance of larynx
What is the vallecula?
A depression between the tongue base and epiglottis
What is the significance of the vallecula?
It is where a laryngoscope is put
What is the thyroid cartilage attached to superiorly?
Hyoid bone
How is the thyroid cartilage attached to the hyoid bone?
Thyrohyoid membrane
What is the thyroid cartilage attached to inferiorly?
Cricoid cartilage
How is the cricoid cartilage attached to the thyroid cartilage?
Cricothyroid membrane
What is the significance of the cricothyroid membrane?
In acute laryngeal obstruction, can be punctured to enable the patient to breathe
What is the thyroid cartilage made up of?
Two lateral plates meeting in midline as a prominent V called laryngeal prominence
What vertebral level is the thyroid cartilage at?
Superior pole level with C4
What does the thyroid cartilage have attachments for?
Epiglottis and vocal cords
What shape are the cricoid cartilages?
Signet-ring shaped
How is the cricoid cartilage unique?
It is the only complete ring of cartilage throughout the respiratory tract
What does the cricoid cartilage articulate with?
Thyroid and arytenoid cartilages
What is the cricoid cartilage attached to inferiorly?
Trachea
How is the cricoid cartilage attached to the trachea?
Cricotracheal membrane
What is the clinical significance of the cricoid cartilage?
Cricoid pressure can be used during intubation
How is cricoid pressure used during intubation?
Press from front, flap compresses oesophagus and stops anything from coming up
Where do the arytenoid cartilages sit?
On top of the cricoid cartilage posteriorly, one on each side
What is found passing forwards from arytenoids to the back of the thyroid cartilages, just below epiglottic attachment?
Two folds of mucosa lining the interior of larynx
What are the names of the folds of mucosa lining the interior of the larynx?
Vestibular fold
True vocal cord
What is the vestibular fold also known as?
The false vocal cord
Where does the vestibular fold form?
On each side
What does the true vocal cord contain?
Vocal ligament
What is found between the vocal cords?
A space called the rima glottides
What do the mucosal folds demarcate?
The three zones of the larynx
What are the three zones of the larynx?
Supraglottic compartment, or vestible
Glottis compartment
Subglottic compartment
Where is the supraglottic compartment?
Above false vocal cords
Where is the glottis compartment?
Between false and true vocal cords
Where is the subglottic compartment?
Between true vocal cords and first tracheal ring
What connects all the cartilages of the larynx together?
Cricotracheal membrane
What happens to the upper edge of the cricotracheal membrane?
Its upper edge is slightly thickened to form the vocal ligament
What do the vocal cords consist of?
Vocal folds
Vocalis muscle
Stratified squamous epithelium
Where do the vocal cords attach?
Inner surface of thyroid cartilage anteriorly
Arytenoids posteriorly
What is the fixed attachment of the vocal cords?
Inner surface of thyroid cartilage
What is the importance of the attachment of the vocal cords to the arytenoids?
Moveable to open and close the vocal cords
How are the arytenoids involved in the movement of the vocal cords?
They pivot on cricoid cartilage when pulled by intrinsic laryngeal muscles to move cords
What are the functions of the muscles of the larynx?
Open glottis in inspiration
Close vestibule in swallowing
Alter tone of true vocal cords in phonation
What are the muscles of the larynx collectively called?
Intrinsic muscles of the larynx
What is true of one of the intrinsic muscles. the cricothyroid muscle?
It actually lies externally
What is the function of the cricothyroid muscle?
Tensing and slightly adducting the vocal cords
How does the cricothyroid muscle achieve its function?
By the tilting action of the thyroid cartilage on the cricoid cartilage
What is the effect of tensing the vocal cords?
Higher pitched sounds can be made
What is the cricothyroid innervated by?
The external laryngeal nerve
What is the external laryngeal nerve a branch of?
The superior laryngeal nerve, a branch of CN X
What are the intrinsic muscles of the larynx, apart from the superior laryngeal nerve, innervated by?
Recurrent laryngeal nerve
What do the rest of the intrinsic muscles, other than the cricothyroid, constitute?
An encircling sheet
What do many of the intrinsic muscles of the larynx act to do?
Move the arytenoid cartilage at the cricoarytenoid joint
What is the result of the movement of the arytenoid cartilage at the cricoarytenoid joint?
Allows opening and closing of the vocal cords, either directly or indirectly
What are the movements of the vocal cords important in?
Allowing the passage of air in and out of the lungs
Phonation
Protecting the airways during swallowing
What does the cricoarytenoid on each side do posteriorly?
Rotates the arytenoids outwards
What is the function of the outward rotation of the arytenoids?
Seperates (abducts) the vocal cords
What would happen without the cricoarytenoid action?
The vocal cords would resume a permanent adducted position, and block passage of air
What do the aryepiglottis and thyroepiglottis muscles attach to?
The epiglottis
What is the action of the aryepiglottis and thyroepiglottis?
Ensure laryngeal inlet is safely covered by the epiglottis
What does the aryepiglottis and thyroepiglottis work in conjunction with in ensuring that the laryngeal inlet is safety covered by the epiglottis?
The contraction of the suprahyoid muscles and pharyngeal muscles, which pull the larynx upwards, helping tilt the epiglottis further
What is the importance of ensuring the laryngeal inlet is safety covered by the epiglottis?
It ensures fluids/food directed away from laryngeal opening
What supports the larynx in its function?
Infrahyoid and suprahyoid muscles
How do the infra- and suprahyoid muscles support the larynx in its function?
They depress and elevate the hyoid
What provides innervation to the larynx?
Branches of the vagus nerve
What branches of the vagus nerve supply innervation to the larynx?
Superior laryngeal branches and recurrant laryngeal nerve
What does the superior laryngeal nerve branch into?
The internal and external laryngeal
What does the internal laryngeal nerve supply?
Sensory to the supraglottic compartment
What does the external laryngeal nerve supply?
Motor to cricothyroid
What does the cricothyroid do?
Moves thyroid for phonation
What does the recurrent laryngeal nerve innervate?
Laryngeal mucosa above vocal cords
Sensory to subglottic
Motor to intrinsic muscles
What are the superior and recurrent laryngeal nerves accompanied by?
Arterial branches from superior and inferior thyroid arteries
Why is knowledge of the relationship between the superior and recurrent laryngeal nerves, and the superior and inferior thyroid arteries, very important?
Important when operating on thyroid gland to avoid causing a vocal cord paralysis
What happens to the larynx during swallowing?
The epiglottis is pulled down to cover larynx. and the larynx is pulled up and forwards
What is the purpose of pulling the larynx up and forwards in swallowing?
Directs the bolus lateral to the epiglottis into the piriform fossae
What is the cervical plexus formed by?
Anterior pituitary rami of first four cervicla nerves
Where does the cervical plexus lie?
On surface of scalenus medius and levator scapulae muscles, deep to internal jugular vein
What does the cervical plexus emerge from?
The posterior border of the sternocleidomastoid
What does the cervical plexus lie within?
The posterior triangle
What do the sensory branches of the cervical plexus innervate?
Skin of neck
Part of scalp
Ear
Superior part of thorax
What do the muscular branches of the cervical plexus form?
A loop known as ansa cervicalis
What does ansa cervicalis give rise to?
Nerves supply most of the four paired infrahyoid muscles
What is one of the important nerves of the ansa cervicalis?
Phrenic nerve
What nerve roots does the phrenic nerve carry?
C3 and C4, and roots from ventral ramus of C5
