The Larynx Flashcards
Label the relations of the larynx
Lies under strap muscles
Which strap muscles connect to the larynx?
Stenrothyroid and thyrohyoid
Function of the larynx?
Phonation
Larynx composed of?
Significance?
Pieces of hyaline cartilage which articulate with eachother via tiny plane synovial joints
Allows small gliding movements between thyroid and cricoid cartilages + arytenoid and cricoid cartilages
What forms the laryngeal prominence (Adam’s apple)?
Thyroid cartilage - largest cartilage of the larynx
Label the thyroid cartilage
Attachments of thyroid cartilage?
Attaches to hyoid bone via thyrohyoid membrane - ensures muscles that elevate hyoid also elevate laryx
Articulates cricoid cartilage inferiorly
Muscle attachments thyroid cartilage?
Provides attachment for 2 muscles of anterior triangle - sternothyroid + thyrohyoid
And inferior constrictor of pharynx
Shape cricoid cartilage?
The cricoid cartilage forms a signet ring shape, with the thin band of the ring anterior and the signet gemstone part facing posteriorly
Label cricoid cartilage
Attachments of cricoid cartilage?
It articulates with the thyroid and arytenoid cartilages.
It also provides an area of attachment for several intrinsic muscles of the larynx – for example posterior cricoarytenoid.
The trachea sits inferior to the cricoid cartilage and is attached to it by a thickened membrane – the cricotracheal ligament
What’s this?
Arytenoid cartilage
Label arytenoid cartilage features
muscular process = attachment of the posterior and lateral cricoarytenoid muscles which act to move the vocal folds
Vocal process = attachment for vocal folds
Label the larynx
+ function
Epiglottis composed of?
Communicates with larynx?
Odd one out - elastic cartilage
The other cartilages of the larynx are hyaline
Sits over opening of larynx + communicates with it via aryepiglottic folds
Label
Attachments of epiglottis?
muscles?
Anterior = to body of hyoid bone and posterior surface of thyroid cartilage
Lateral = to arytenoid cartilages via aryepiglottic folds
Mucous membrane covering reflected onto posterior surface of tongue – median glossoepiglottic fold and lateral pharyngoepiglottic folds
There are no muscles that move the epiglottis, it passively bends over the opening of the larynx when a food bolus pushes on its surface
Label
Ligaments of the larynx?
Arytenoid cartilages to epiglottis = quadrangular ligament – free edge is vestibular ligament (false vocal fold)
Cricoid, thyroid + arytenoid = cricothyroid membrane – free upper border is the vocal ligament (true vocal cord)
Label
Upper/lower borders?
The lower free edge of the quadrangular ligament forms the false vocal fold.
The upper border of the quadrangular ligament is called the aryepiglottic fold.
Purpose of false vocal fold?
True vocal fold?
Most posterior space between the vocal folds?
The vestibular (false) fold protects the true vocal fold beneath it
The true vocal folds are adduct + abduct to disrupt the flow of air through the larynx. This movement combined with the tension in the vocal folds creates sound.
Rima glottidis – the most posterior space between the vocal folds
Label
Label
you can see the vestibular fold most superior and the true vocal fold inferior
What muscle is this?
Label
It’s cricothyroid
Attachments cricothyroid?
Function?
Innervation?
Attach from cricoid cartilage to –> lamina + inferior cornu of thyroid cartilage
Tense + elongate vocal folds (i.e. increase distance between thyroid cartilage + vocal processes of arytenoid - thyroid forward and cricoid tilted backward) —> changes pitch
Innervation = external laryngeal branch of vagus
What muscle is this?
Whats the smaller muscle (label)?
It’s thyroarytenoid
Attachments thyroarytenoid?
Upper fibres?
Function?
Innervation?
Inner surface of angle of thyroid cartilage to —> anterolateral surface of arytenoid cartilages
Upper fibres run alongside vocal ligament = and are called vocalis
Function = opposite to cricothyroid. Pulls arytenoids closer to thyroid cartilage so relaxes vocal cords (changes pitch)
Innervation = recurrent laryngeal nerve
What muscle is this?
posterior cricoarytenoid
attachments cricoarytenoid?
function?
innervation?
Posterior lamina of cricoid cartilage to
–> muscular process of arytenoid cartilage
Pulls muscular process of arytenoid backwards – rotating vocal process laterally = abduction of vocal fold (opens airway)
innervation = recurrent laryngeal branch of vagus (CN X)
What muscle is this?
posterior cricoarytenoid
What muscle is this
Lateral cricoarytenoid
attachments lateral cricoarytenoid?
Function?
Innervation?
Upper edge of arch of cricoid cartilage to
—> muscular process of arytenoid cartilages
Function is opposite to posterior cricoarytenoid. Pulls muscular process forwards – rotate vocal process medially = adduction of vocal fold
Recurrent laryngeal branch of vagus (CN X)
What muscle is this?
Oblique arytenoid
Attachments oblique arytenoid?
Function?
Innervation?
From muscular process of arytenoid cartilage to —> apex of opposite arytenoid cartilage
(some fibres also form aryepligottic muscles in aryepiglotic fold)
Function = sphincter of laryngeal inlet. Pulls arytenoid cartilages closer together + also edges of quadrangular membrane
Recurrent laryngeal branch
What muscle is this?
Transverse arytenoid
Transverse arytenoid attachments?
Function?
Innervation?
from posterior + medial surfaces of arytenoid cartilages to opposite arytenoid cartilage
function = closes rima glottidis
recurrent laryngeal nerve
Intrinsic muscles of larynx summary table
- muscle, action, innervation
Label
Label
Blood supply to the larynx?
Originate from thyroid arteries, which come from external carotid (superior) and subclavian arteries (inferior)
Label veins of the larynx
where do they drain?
The veins follow a similar pathway to the arteries, draining into the superior and inferior thyroid veins.
The superior veins drain into the internal jugular vein on both sides, and both of the inferior veins drain into the left brachiocephalic vein
lymph drainage larynx?
paratracheal and deep cervical nodes
Label
Photograph A shows the basic features of the larynx. The thyroid cartilage forms the laryngeal prominence (Adam’s apple). The cricoid cartilage forms a complete ring of cartilage immediately distal to the thyroid cartilage. The hyoid bone lies proximal to the thyroid cartilage. The larynx permits phonation – the creation of sounds for speech. To achieve this the larynx uses vocal folds, small intrinsic muscles and moveable cartilages. Photographs B (anterior view) and C (lateral view) show cricothyroid, one of the intrinsic muscles of the larynx. Cricothyroid passes between the cricoid cartilage and the lower border of the thyroid cartilage (one each side). Cricothyroid acts to tense the vocal folds and is innervated by the external laryngeal branch of the vagus nerve (CN X).
Photograph A shows the posterior surface of the pharynx. If the muscles of the posterior wall of the pharynx are sectioned and reflected, then the structures shown in photograph B are revealed. The surfaces of the epiglottis and cartilages of the larynx are covered in mucosa.
Photograph C shows the positions of the arytenoid cartilages (also covered with mucosa).The mucous membrane from the epiglottis passes towards the arytenoid cartilages – this is the aryepiglottic fold (the superior edge of the quadrangular membrane). The thickened inferior margins of the quadrangular membranes form the vestibular ligaments (the internal parts of the vestibular folds).
Photograph A shows the posterior surface of the cricoid cartilage and posterior cricoarytenoid. Posterior cricoarytenoid attaches to the posterior lamina of the cricoid cartilage and inserts into the posterior surface of the muscular process of the arytenoid cartilage (one each side).
Posterior cricoarytenoid acts to abduct the vocal cords and is innervated by the recurrent laryngeal nerve.
Photograph B also shows the posterior surface of the cricoid cartilage but with more mucosa reflected to show the transverse and oblique arytenoid muscles. Oblique arytenoid passes from the muscular process of one arytenoid cartilage to the apex of the opposite arytenoid cartilage. It acts to narrow the laryngeal inlet and is innervated by the recurrent laryngeal nerve.
Transverse arytenoid passes from the posterior and medial surface of one arytenoid cartilage to the same places on the opposite arytenoid cartilage. It acts to close the posterior part of the rima glottidis and is innervated by the recurrent laryngeal nerve.
Photograph A shows the posterior surface of the cricoid cartilage and a white dotted line to indicate where to section the cartilage to reveal its internal structures.
Photograph B shows the internal surface of the larynx. The vestibular (false) and true vocal folds are highlighted by the blue circle. Photograph C shows a closer view of this area. The vestibular fold is the inferior edge of the quadrangular membrane and acts to protect the true vocal folds. The true vocal folds contain the vocal ligaments (cords) which are moved by the intrinsic muscles of the larynx to produce sound. The vocal cords are the upper border of the cricothyroid ligament.
This slide shows an internal view of the larynx and the final two intrinsic muscles. Lateral cricoarytenoid arises from the upper border of the cricoid cartilage and inserts into the anterior surface of the muscular process of the arytenoid cartilage (one each side). It acts to adduct the vocal folds and is innervated by the recurrent laryngeal nerve.
Thyroarytenoid arises from the inner surface of the thyroid cartilage and inserts into the arytenoid cartilage (one each side). The part of thyroarytenoid associated with the true vocal folds is called vocalis. Thyroarytenoid acts to relax the vocal folds and is innervated by the recurrent laryngeal nerve.
