24 - Larynx Flashcards
What is the function of the larynx?
- allows passage of air to trachea
- protective sphincter of airway
- organ of phonation
Where is the larynx located?
- C3-C6
- tip of epiglottis to cricoid cartilage
Describe the openings of the larynx.
- opens superiorly into larygnopharynx via laryngeal inlet
- opens inferiorly and is continuous with trachea
What are the cartilages of the larynx?
- 9 total
- epiglottis
- thyroid
- cricoid
- arytenoid x2
- cuneiform x2
- corniculate x2
What type of cartilage makes up the larynx?
- all hyaline cartilage
- except for epiglottis made up of elastic
How does the cricoid cartilage differ from the other cartilage of the larynx?
Only complete ring
Where is the superior thyroid notch located?
Sits superior to the laryngeal prominence, formed by the thyroid cartilage
Describe the cricothyroid joint.
- synovial joint formed by the articulation of the cricoid and thryoid cartilage
- allows for gliding and rotation of larynx
- affect pitch of voice
Describe the epiglottis.
- leaf shaped elastic cartilage
- covered in mucosa
- attached to back of thyroid cartilage by thryo-epiglottic ligament
- attached to the hyoid bone by hyo-epiglottic ligament
What is the function of the epiglottis?
- boundary between larynx and laryngopharynx
- protects airway from fluids and bolus
Describe the arytenoid cartilage.
- pyramidal shaped hyaline cartilage
- articulates with corniculate (superiorly) and cricoid cartilage (inferiorly)
- apex forms site for aryepiglottic fold attachment
- sits superior to cricoid cartilage
What are the extrinsic ligaments and membranes of the larynx?
- thyrohyoid membrane
- median and lateral thyrohyoid ligaments
- ligaments are formed by thickening of the membrane anteriorly and posteriorly respectively
What cartilage is found within the lateral thryohyoid ligament?
Triticeal cartilage
What are the intrinsic ligaments and membrane of the larynx?
- quadrangular membrane
- cricothyroid ligament (criciovocal membrane)
- vocal ligament
Describe the quadrangular membrane.
- extends from arytenoid cartilage to thyroid cartilage to the epiglottis
- has free inferior margin which forms vestibular ligament
Describe the cricothyroid ligament.
- membrane extends from cricoid to arytenoid to thyroid cartilage
- thickens anteriorly to form median cricothryoid ligament
Describe the vocal ligament.
- superior free edge of cricothryoid ligament
- forms aryepliglottic fold
What are the laryngeal folds?
- mucosa membrane that forms over the free edges of the intrinsic ligaments of the larynx
- aryepliglottic
- vestibular
- vocal
Describe the aryepligottic fold.
- forms over the superior free edge of the quadrangular membrane
- forms the laryngeal inlet
- protective sphincter of larynx
Describe the vestibular folds.
- forms over inferior free edge of quadrangular membrane (vestibular ligament)
- protective function
Describe the vocal folds.
- true vocal cords
- forms over superior free edge of cricithyroid cartilage (vocal ligament)
What is the rima glottidis?
Opening/space between vocal cords
What are the extrinsic muscles of the larynx?
- infrahyoid muscles
- suprahyoid muscles
- stylopharyngeus
What is the role of the extrinsic laryngeal muscles?
To raise/depress the larynx
What are the intrinsic laryngeal muscles?
- posterior cricoarytenoid
- lateral cricoarytenoid
- transverse arytenoid
- oblique arytenoid
- thryoarytenoid
- cricothryoid
- vocalis
What are the functions of the intrinsic laryngeal muscles?
- open/close rima glottidis
- alter tension of vocal folds
- open close laryngeal inlet
What muscles act to open/close the rima glottidis?
- abductors/adductors
- posterior cricotarytenoid abducts vocal folds (opens)
- transverse arytenoid and lateral cricoarytenoid adduct (closes)
Describe the location of the transverse arytenoid.
Runs transversely across the arytenoid cartilage
Describe the location of the lateral cricoarytenoid muscle.
Attaches from the lateral aspect of the cricoid cartilage to the arytenoid cartilage, running obliquely
Describe the location of the posterior cricoarytenoid muscle.
Runs from the midline of the posterior aspect of the cricoid cartilage to the lateral aspect of the arytenoid cartilage
What muscles act to alter the tension of the vocal folds?
- tensors/relaxers
- cricothyroid lengthens the vocal folds
- thyroarytenoid relaxes vocal folds (vocalis is the upper part)
What effect does lengthening the vocal folds have on phonation?
Increased tension = higher pitch
What effect does shortening the vocal folds have on phonation?
Reduced tension = lower pitch
Describe the location of the thyroarytenoid muscle.
Runs transversely from the posterior of the thyroid cartilage to the arytenoid cartilage
Describe the location of the cricothyroid muscle.
Straight and oblique part on the anterior aspect of the cricoid cartilage which attach to the thyroid cartilage
What muscles act to open/close laryngeal inlet?
- oblique arytenoid muscle, acts a purse string (closure)
- extrinsic muscles also contribute
- opening via descent of larynx and elastic recoil
Describe the location of the oblique arytenoid muscles.
- form a cross as they run obliquely from the lateral aspect of the arytenoid cartilage, cross at the midline and continue to other lateral side
- continue superiorly as the aryepiglottic part
What is the motor innervation of the larynx?
- all muscles supplied by recurrent laryngeal nerve
- EXCEPT cricothyroid supplied by external branch of superior laryngeal nerve
- both are branches of CN X
What is the sensory innervation of the larynx?
- sensation superior to vocal fold supplied by internal branch of superior laryngeal nerve
- sensation inferior to vocal folds supplied by the recurrent laryngeal nerve
- both are branches of CN X
Describe the shape of the rima glottidis during normal breathing.
- quiet respiration
- vocal and vestibular folds abducted (open)
- rima glottidis triangular in shape
- vestibule open
Describe the shape of the rima glottidis during forced inspiration.
- opened wider by the cricoarytenoid muscle, wider based triangular
- vestibule open
Describe the shape of the rima glottidis during phonation.
- vocal cords adducted
- vestibule open
- rima glottidis is closed, air forced through causing vibration
Describe the shape of the rima glottidis during effort closure.
- vocal and vestibular folds adducted (closed)
- rima glottidis and vestibule closed
- valsalva manoeuvre
What is the valsalva manoeuvre used for?
- when lifting weights
- bowel moments
- equalising pressure in the middle ear
