004 anatomy of larynx and supra laryngeal vocal slides Flashcards
what are the functions of the larynx?
- protects airway, especially during swallowing by closing it with the epiglottis
- controls airflow through respiratory tract e.g. intense exercise, coughing, abdominal pressure in defecation, childbirth
- controls airflow during phonation (singing, speaking ,shouting)
what is the anatomical location of the larynx?
- anterior neck, suspended below the hyoid bone
- C3-6
- continuous with the trachea, opens superiorly into the laryngopharynx
- covered anteriorly by infrahyoid muscles and laterally by lobes of thyroid gland
- visible as ‘Adams apple
what are the 2 regions of the larynx?
- superior ( vestibule)
- inferior (atrium)
- divided by the vocal folds
what are the 4 main components of the larynx?
- cartilaginous skeleton
- ligaments
- muscles (intrinsic and extrinsic)
- mucous membranes (lines with respiratory epithelium)
describe the overall structure of the larynx
- cartilaginous skeleton, held together by ligaments, muscles and membranes
- 3 parts = supraglottis, glottis and subglottis
what is the membrane inside the larynx?
- ciliated columnar respiratory epithelium
what is the supraglottis of the larynx?
- epiglottis and vestibular folds
what is the glottis of the larynx?
- contains vocal cords
- space between vocal cords = rima glottidis
what is the subglottis of the larynx?
- below the vocal cords down to the inferior border of the cricoid cartilage
what are the different types of cartilage in the larynx?
- 9 types
- 3 unpaired (thyroid, cricoid, epiglottis), 6 paired (arytenoid, corniculate, cuneiform)
what are the 3 unpaired cartilages of the larynx?
- thyroid, cricoid, epiglottis
describe the structure of the thyroid cartilage
- large prominent = makes adams apple
- composed of 2 sheets/laminae that join to form laryngeal prominence (adams apple)
- posterior inferior and superior horns (cornu)
= superior horns articulate with hyoid bone
= inferior horns articulate with cricoid cartilage
what is the name of the structure that forms the Adams apple?
- laryngeal prominence on the thyroid cartilage
what do the superior and inferior horns of the thyroid cartilage articulate with?
- superior = hyoid bone
- inferior = cricoid cartilage
describe the structure of the cricoid cartilage
- inferior to the thyroid cartilage
- complete ring of hyaline cartilage (looks like signet ring, thinner at the front, thicker at the back)
- inferior border of the larynx at C6
- articulates with paired arytenoid cartilages posteriorly
describe the structure of the epiglottis
- a leaf-shaped plate of elastic cartilage
- marks entrance of larynx
- ‘stalk’ is attached to anterior part of thyroid cartilage
- during swallowing, it moves towards arytenoid cartilages to close off larynx
describe the structure of the arytenoid cartilage
- paired pyramidal shaped structures that sit on cricoid cartilage posteriorly
- apex = articulates with corniculate cartilage
- base = articulates with cricoid cartilage
- vocal process = provides attachments for vocal ligament
- muscular process = provides attachment for posterior and lateral cricoarytenoid muscles
describe the structure of the corniculate cartilages
very small minor cartilaginous structures
- sit on the apices of arytenoid cartilages
what are the extrinsic ligaments of the larynx?
- thyrohyoid membrane
- hypo-epiglottic ligament
- cricotracheal ligament
- cricothyroid ligament
what is the thyrohyoid membrane?
- extrinsic ligament between superior aspect of thyroid cartilage and hyoid bone
- median and lateral thickenings
what is the hypo-epiglottic ligament?
- extrinsic ligament connects hyoid bone to the anterior aspect of epiglottis
what is the cricothyroid membrane/ligament?
- extrinsic and intrinsic ligament
- connects cricoid to thyroid and arytenoid cartilages
- antero-medial thickening = extrinsic
- originating from the cricoid ligament and extends superiorly to form vocal ligament = intrinsic
- also attaches anteriorly to thyroid cartilage and posteriorly to arytenoids
what is the cricotracheal ligament?
- extrinsic ligament
- connects cricoid cartilage with the first cartilage of the trachea
what are the intrinsic ligaments of the larynx?
- quadrangular membranes –> vestibular ligament
- cricothyroid ligament –> cricovocal membrane –> vocal ligament
what is the cricovocal ligament?
- intrinsic ligament originating from the cricothyroid ligament
- free superior border thickens to form the vocal ligaments/folds
what is the quadrangular membrane?
- intrinsic ligament
- connects epiglottis lateral margins to arytenoid and thyroid cartilages
- lower margin thickens and forms the vestibular ligaments/folds
what are the vestibular ligaments/folds
- thickened part of quadrangular membranes
- forms vestibular recesses which are glands that secrete mucus to lubricate folds
what are the different types of intubation and reasons why?
- usually just use intubation tube through the mouth into the larynx to intubate/help with breathing
- if intubation is not possible e.g. obstructions, tumours, swellings, fractures or if long-term access is needed, it is gained through the cricothyroid membrane (coniostomy) or through the trachea (tracheostomy)
what are the intrinsic muscles of the larynx used for?
- act on individual components of the larynx
- control inlet to the larynx, for swallowing
- control size of rima glottidis (space between vocal folds) to control airflow in swallowing and phonation
- control tension/length of vocal folds to control pitch of sound
what are the intrinsic muscles of the larynx innervated by?
- all innervated by inferior laryngeal nerve except from cricothyroid = external branch of superior laryngeal nerve
( but all derived from vagus nerve)
what are the names of the intrinsic larynx muscles?
- cricothyroid, thyroartenoid, posterior, lateral cricoarytenoids, transverse and oblique arytenoids, aryepiglottic, thyroepiglottic, vocalis muscles
what muscles are used in closing the sphincter/inlet of the larynx?
- aryepiglottic muscle
- oblique arytenoid muscles (cross between arytenoid cartilages, posterior)
what muscle is used to open the sphincter/inlet of the larynx?
- thyroepiglottic muscle = very small and hard to see
- doesn’t need to do much as larynx is pretty much open in relaxed state
what muscles relaxes the vocal folds?
thyroartyenoid muscles
= slows down vibrations = opening rima glottidis = deeper sounds
what muscles tenses the vocal folds?
- cricothyroid muscles
- increase vibrations = higher pitch sounds
what muscles adjust the tension in the vocal folds?
- vocalis muscle (between the thyroid cartilage and cricoid cartilage, follows path of thyroarytenoid muscles)
what do the posterior cricoarytenoids do?
- abduct and externally rotate vocal folds (open rima glottidis)
what do lateral and transverse cricoarytenoids do?
- adduct and internally rotate vocal folds (close rima glottidis)
what is a?
epiglottis
what is b?
aryepiglottic muscle
what is c?
oblique arytenoid muscle
what is d?
transverse arytenoid muscle
what is e?
posterior cricoarytenoid muscle
what is f?
cricoid cartilage
what is g?
cricothyroid muscle
what is h?
aryepiglottic muscle
what is i?
oblique and transverse arytenoid muscles
what is j?
posterior cricoarytenoid muscle
what is k?
cricothyroid muscle
what is l?
thyroepiglottic muscle
what is m?
thyroarytenoid muscle
what is n?
lateral cricoarytenoid muscle
what is o?
arytenoid cartilage
what is p?
cricoid cartilage
what is q?
posterior cricoarytenoid muscle
what is r?
lateral cricoarytenoid muscle
what is s?
transverse and oblique arytenoid muscles
what is t?
cricothyroid muscles
what is u?
thyroarytenoid muscle
what is v?
vocalis muscle
what is w?
vocal ligament
what is x?
thyroid cartilage
what are the extrinsic muscles of the larynx and what are their functions?
suprahyoid muscles = stylohyoid, digastric, mylohyoid, geniohyoid, styloglossus (all raise hyoid/larynx)
infrahyoid muscles = sternohyoid, sternothyroid, thyrohyoid, omohyoid (all lower/depress hyoid/larynx)
what is the sensory innervation of the larynx?
- branches of the vagus nerve (CNX)
- recurrent laryngeal nerve = sensory innervation of subglottis (below vocal folds)
- superior laryngeal nerve = sensory innervation of supraglottis (above vocal folds)
what is the motor innervation of the larynx?
- branches of the vagus nerve (CNX)
- recurrent laryngeal nerve = motor innervation to all muscles except cricothyroid
- superior laryngeal nerve = motor innervation to cricothyroid
what is the arterial supply to the larynx?
- external carotid artery –> superior thyroid artery –> superior laryngeal artery = supplies supraglottis
- thyrocervical trunk –> inferior thyroid artery –> inferior laryngeal artery = supplies subglottis
what is the venous drainage of the larynx?
- superior laryngeal vein –> superior thyroid vein –> internal jugular vein
- inferior laryngeal vein –> inferior thyroid vein —> left brachiocephalic vein
how is speech produced from the larynx?
- a source of acoustic energy (air stream from the lungs) is shaped by the vocal folds
- it is then modulated by the filter, supralaryngeal vocal tract, to form speech elements e.g. vowels, consonants
- to produce different speech elements, the supralaryngeal vocal tract changes in length/shape/diameter
how does the vibrations of the vocal folds change depending on the pitch of sound?
- higher pitch of sound = faster flapping/vibrations of vocal folds
- lower pitch of sound = slower flapping/vibrations of vocal folds
what is the clinical relevance if there is damage to the recurrent laryngeal nerves?
- unilateral or bilateral palsy (1 or both damaged)
- can be damaged due to cancer, aortic aneurism, cervical lymphadenopathy, neck surgery (especially thyroid surgery)
- unilateral = 1 vocal cord paralysed = other compensates, minor symptoms e.g. hoarseness of voice
- bilateral = both vocal cords paralysed = no speech/phonation and breathing and swallowing is impaired
