1. Anatomy and Physiology of the Larynx
7/15/2012
Dr. Supreet Singh Nayyar, AFMC
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2. Objectives To discuss the basic anatomy of the larynx
To enumerate the main functions of the larynx
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3. Embryology Respiratory system – outgrowth of primitive pharynx
3.5 weeks – laryngotracheal groove, ventral aspect of foregut
3 weeks - Hypobrancial eminence – gives rise to furcula -> epiglottis
5th week – Arytenoid masses
5-7 weeks – laryngeal lumen is obliterated
9 weeks – oval shape lumen reestablished
8-10 weeks – Formation of true and false vocal cords
12th week – ventricles
Laryngeal muscles – derivatives of mesoderm of 4th and 5th arches (CN X)
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4. Laryngeal Cartilages Paired Unpaired: Arytenoid cartilage
Corniculate cartilage
Cuneiform cartilage
Unpaired:
Thyroid cartilage
Cricoid cartilage
Epiglottis
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5. Thyroid Cartilage Hyaline cartilage Largest
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Hyaline cartilage
Largest
Encloses the larynx anteriorly and laterally
Two alae
Ossification
This cartilage has two alae/wing which meet anteriorly, they form a depression called the THYROID NOTCH before meeting at the protruberance of the Adam’s apple or laryngeal prominence. Posteriorly, each wing has a superior cornu (extending upward about 2 cm) and inferior cornu (articulates w/cricoid cartilage below; ONLY DIRECT ARTICULATION, all others being maintained by muscles or ligaments)
Ossifies at years of age, begins in the inferior margin and progress cranially

6. Cricoid Cartilage Hyaline cartilage
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Hyaline cartilage
Directly below the thyroid cartilage
Strongest
Shape: Signet ring
Lamina – flat portion
Only complete annular support of the larynx
Articulates w/ Inferior cornu of the thyroid cartilage
Ossifies after the thyroid cartilage, first part to be calcified being the superior portion (w/c can be mistaken for a foreign body) Calcification progresses caudally.
Lamina – flat portion of the ring llocated posteriorly and extends upward to form the POSTERIOR border of the larynx
Only complete annular support of the laryngeal skeleton; preservation essential to maintain the enclosed airways.
Level: Adult: C6-C7 Children: C3-C4
Posterolaterally, cricoid articulates w/ Inferior cornu of the thyroid cartilage, which forms true synovial joints (permit a ROCKING action of the cricoid cartilage on the thyroid cartilage and a slight anteroposterior SLIDING motion (cricoid cart. Supports the 2 arytenoid cartilages on posterosuperior aspect)

7. Epiglottis Fibroelastic cartilage Leaf-shaped structure
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Fibroelastic cartilage
Leaf-shaped structure
Petiole – small narrow portion of the glottis
Attached to the INSIDE of the thyroid cart. Anteriorly and projects upward and backward above the laryngeal opening.
Petiole – small narrow portion of the glottis that is attached to the thyroid cart.
The epiglottis is attached to the hyoid bone by the hyoepiglottic ligament.
To the posterior part of the tongue by the median glossoepiglottic fold.
To the sides of the pharynx by the lateral glossoepiglottic folds.
To the thyroid cartilage by the thyroepiglottic ligament.
The mucous membrane covering the epiglottis is reflected to the posterior part of the tongue as one medial and two lateral glossoepiglottic folds. Between these folds are depressions called epiglottic valleculae.

8. Arytenoid Cartilage Mostly hyaline cartilage Smaller in size
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Mostly hyaline cartilage
Smaller in size
Responsible for opening and closing of the larynx
Shape: pyramidal
Calcify at the 3rd decade (Hyoid – ossifies fr. 6 centers shortly after brith, complete by 2 years of age)
Arytenoids rest on the upper edge of the cricoid lamina at the posterior border of the larynx

9. Arytenoid Cartilage Anterior Lateral Articulation
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Anterior
Vocal process - receives the attachement of the mobile end of each VC
Lateral
Muscular process
Articulation
Cricoarytenoid joint
Mobile end of VC – posterior
Lateral promincence of each arytenoid cart. Is known as Muscular process, becoz of insertion site of numerous muscles
Articulation of arytenoids with cricoid cart. Is at the CRICOARYTENOID JOINT, w/c permits a WIDE range of motion in 3 directions

10. Corniculate Cartilages
Fibroelastic
Cartilages of Santorini
Small cartilages above the arytenoid and in the aryepiglottic folds
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11. Cuneiform Cartilages Firboelastic cartilages Cartilages of Wrisberg
Elongated pieces of small yellow elastic cartilage in the aryepiglottic folds
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12. Triticeous Cartilage Cartilago triticea
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Cartilago triticea
Small elastic cartilage in the lateral thyrohyoid ligament
When calcified, it can be mistaken as a foreign bidy in soft tissue Xray films

13. Laryngeal Ligaments Intrinsic Extrinsic Elastic membrane
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Intrinsic
Elastic membrane
Quadrangular membrane
Conus elasticus (cricovocal membrane)
Median cricothyroid ligament
Vocal Ligament
Thyroepiglottic ligament
Extrinsic
Thyrohyoid membrane and ligaments
Cricothyroid membrane and ligaments
Cricotracheal ligament
Epiglottis

14. Extrinsic Ligaments Thyrohyoid membrane pierced on each side by:
1. Superior laryngeal vessels
2. Internal branch of superior laryngeal nerve
Median thyrohyoid ligament
– thickened median portion
Lateral thyrohyoid ligament
– thickened posterior border
- where cartilago triticea is often found
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Thyrohyoid m&L –attach thyroid cart. To hyoid bone

15. Extrinsic Ligaments Cricothyroid membrane and ligaments
May be pierced for emergency tracheotomy (cricothyrotomy)
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Obvious from its name, the CT m&L connect the thyroid and cricoid cart.
Cricothyrotomy – little fear of bleeding; however becoz of proximity to the vocal cords, this space shld not be used for prolonged intubation, as scar tissue may be produced.

16. Extrinsic Ligaments Cricotracheal Ligament Epiglottis
Attaches the cricoid cartilage to the first attached ring
Epiglottis
suspended in position by membranous connections to the hyoid bone, thyroid cartilage and base of the tongue
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17. Intrinsic Ligaments Elastic membrane Quadrangular membrane
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Elastic membrane
Divided into upper and lower parts by the ventricle of the larynx
Quadrangular membrane
Upper part of the elastic membrane
Boundaries
Epiglottis , arytenoid, corniculate cartilage, false cord
Forms part of wall between upper pyriform sinus and laryngeal vestibule
Elastic m.-lies beneath the laryngeal mucosa, Fibrous framework of the larynx
Ventricle of the larynx (ventricle of Morgagni)
Quad membrane - Boundaries: extending from LATERAL margin of epiglottis to arytenoid and corniculate cart., and INFERIORLY to the false cord.

18. Intrinsic Ligaments Conus elasticus (cricovocal membrane)
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Conus elasticus (cricovocal membrane)
Lower part of elastic membrane
Composed mainly of yellow elastic tissue
Boundaries
Inferior: superior border of cricoid cartilage
Superoanterior: deep surface of angle thyroid cartilage
Superoposterior: vocal process of arytenoid cartilage
Median cricothyroid ligament – thickened anteior part
Vocal Ligament – free upper edge
Thyroepiglottic ligament
Median cricothyroid ligament – thickened anteior part of conus elasticus
Vocal Ligament – is d free upper edge of the conus elasticus (strongest part), forms the framework of the vocal cord
Thyroepiglottic ligament – ataches epiglottis to the thyroid cartilage

19. Cavity of the Larynx Divided into 3 parts: Vestibule Ventricle
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Divided into 3 parts:
Vestibule
Ventricle
Subglottic space
Divided into 3 parts by 2 folds of mucous membrane, namely the true and false cords.
Vestibule – lies bet. Inlet and edges of false cords
Ventricle (Morgagni) - Deep, spindle-shaped recess bet. True and false cords, lined by a mucous membrane that is covered externally by thyroarytenoid muscle
Subglottic space – lies bet. True VC and lower border of cricoid cartilage

20. Cavity of the Larynx Vestibule – boundaries:
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Vestibule – boundaries:
Anterior: posterior surface of epiglottis
Posterior: interval between arytenoid cartilages
Lateral: inner surface of aryepiglottic folds and upper surfaces of the false cord

21. Cavity of the Larynx Ventricle
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Adduction: Phonation, slit-like appearance
Glottis (rima glottidis)
Abduction: Respiration, wide and triangular
Ventricle
Saccule – conical pouch at anterior part
Saccule – conical pouch that ascends fr anterior part of the ventricle, lies bet. Inner surface of thyroid cartilage and false cord; has numerous mucous glands open into the surface of its lining mucosa for lubricating the vocal cords.
Glottis – space bet. Free margin of the true VC, opening/aperture
Posterior glottic chink in adult: 18-19mm; New born: 4mm; total glottic chink in a newborn: 14mm2

22. Cavity of the Larynx Subglottic space Preepiglottic space Boundaries:
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Subglottic space
Preepiglottic space
Boundaries:
Anterior: thyrohyoid membrane
Anteroasuperior: hyoid
Superior: vallecula
Posterior: part of the epiglottis
Lateral: hyoepiglottic ligament
Subglottic space – lies bet. True VC and lower border of cricoid cartilage
Preepiglottic space – a wedge-shaped space lying in front of the epiglottis

23. Cavity of the Larynx False Cords (ventricular bands) True cords
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False Cords (ventricular bands)
Anteriorly: angle of the thyroid cartilage
Posteriorly: bodies of the arytenoid cartilage
True cords
Voice production
Protection of lower respiratory tract
Anteriorly,: angle of thyroid cartilage
Posteriorly: vocal processes of the arytenoid cartilages
Enclose vocal ligament and a major part of the vocalis muscle
False cords – upper set of two horizontal folds on each side of the laryngeal cavity.
TVC – covering epith. Is closely bound down to underlying vocal ligament, blood supplu here is poor hence the pearly white appearance of the vocal cords in life.

24. Laryngeal Joints Cricothyroid Joint Cricoarytenoid Joint
Between inferior cornu of the thyroid cartilage and facet on the cricoid cartilage at the junction of the arch and lamina
Two movements:
Rotation
Gliding
Cricoarytenoid Joint
bet. base of the arytenoid cartilage and the facet on the upper border of the lamina of the cricoid cartilage
Two movements:
Rotation
Gliding
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Cricothyroid Joint - Synovial joint with a capsular ligament bet. Inferior cornu of the thyroid cartilage and the facet on the cricoid cartilage at the junction of the arch and lamina.
Rotation – thru a transverse axis Gliding – slightly
Cricoarytenoid Joint - Synovial joint with a capsular ligament bet. Base of the arytenoid cartilage and the facet on d upper border of the lamina of the cricoid cartilage
Rotation – arytenoid rotates on a vertical axis, vocal process moves medially or laterally
Gliding – arytenoids move toward or away from each other. (strong posterior cricoarytenoid ligament prevents excessive movements of the arytenoids on the cricoid)

25. Laryngeal Muscles Intrinsic Muscles Extrinsic Muscles Depressor group
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Extrinsic Muscles
Depressor group
Elevator group
Constrictor muscles
Pharyngeal muscles
Intrinsic Muscles
Interarytenoid muscle
Transvers
Oblique
Post. Cricoarytenoid m.
Lateral cricoarytenoid m.
Thyroarytenoid m.
Cricothyroid m.
Intrinsic muscles, all are paired except Interarytenoid m.
Larynx moves up during swallowing, down after.
The extrinsic muscles move the larynx as a whole. The infrahyoid muscles or straps (omohyoid, sternohyoid, and sternothyroid) are depressors of the hyoid bone and the larynx, whereas the suprahyoid muscles (stylohyoid, digastric, mylohyoid and geniohyoid) and the stylopharyngeus are elevator of the hyoid bone and larynx.

26. Depressor muscles Origin Insertion Action
Sternohyoid (C2, C3)
manubrium of sternum and medial end of clavicle
oblique line of the thyroid cartilage
depresses/stabilizes the hyoid bone
Thyrohyoid (C1)
lower border of the hyoid bone
elevates the larynx; depresses/stabilizes the hyoid bone
Omohyoid (C2, C3)
superior border of scapula near the suprascapular notch
inferior border of hyoid bone
depresses, retracts and steadies the hyoid during swallowing and speaking
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Sternothyroid Muscle - a thin muscle located deep to the sternohyoid muscle, and is shorter and wider than it.
Inferior attachment: posterior surface of manubrium of sternum.
Superior attachment: oblique line of thyroid cartilage.
Innervation: C2 and C3 by a branch of the ansa cervicalis.
It depresses the hyoid bone and larynx after it has been elevated by muscles during swallowing and vocal movements.
It also pulls the thyroid cartilage away from the hyoid bone, thereby opening the laryngeal orifice.

27. Elevator muscles Origin Insertion Action
Geniohyoid (C1)
inferior mental spine of mandible
body of hyoid bone
pulls the hyoid bone anterosuperiorly, and shortens the floor of the mouth and widens the pharynx
Digastrics (Ant. CN V; Post. N. VII)
anterior belly-digastric fossa of mandible, posterior belly-mastoid notch of temporal bone
intermediate tendon to body and greater horn of hyoid bone
depresses the mandible and raises the hyoid bone. Also, it steadies the hyoid bone during swallowing and speaking
Mylohyoid (V)
mylohyoid line of mandible
raphe and body of hyoid bone
elevates the hyoid bone, floor of the mouth and the tongue during swallowing and speaking
Stylohyoid (VII)
styloid process of the temporal bone
elevates and retracts the hyoid bone, thereby elongating the floor of the mouth
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28. Constrictor muscles Origin Insertion Action
Middle constrictor m. (CN X)
stylohyoid ligament and greater and lesser horns of hyoid bone
median raphe of pharynx
constricts pharyngeal cavity; influence the position of the larynx during phonation
Inferior constrictor m.
(CN X)
Oblique lines of thyroid cartilage & side of cricoid cartilage
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29. Elevator muscles Origin Insertion Action
Stylopharyngeus
(CN IX)
styloid process of temporal bone
posterior and superior borders of thyroid cartilage with palatopharyngeus muscle
elevates the pharynx and larynx and expands the sides of the pharynx
Salpingopharyngeus (pharyngeal plexus)
cartilaginous part of the auditory tube
blends with palatopharyngeus muscle
elevates the pharynx and larynx and opens the orifice of the auditory tube during swallowing
Palatopharyngeus
hard palate and palatine aponeurosis
lateral wall of pharynx
tenses the soft palate and pulls the walls of the pharynx superiorly, anteriorly and medially during swallowing
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30. Muscles Controlling the Laryngeal Inlet
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Intrinsic Muscles
Origin
Insertion
Action
Interarytenoid m., oblique
(RLN)
muscular process of the arytenoid cartilage
posterior surface of the contralateral arytenoid cartilage, near its apex
draws arytenoid cartilages together, adducting the vocal folds (closure of glottis)
Thyroepiglottic
(ELN)
inner surface of the thyroid cartilage near the laryngeal prominence
lateral surface of the epiglottic cartilage
draws the epiglottic cartilage downward
Muscles controlling the laryngeal inlet

31. Muscles Controlling Movements of the Vocal Cords
Intrinsic Muscles
Origin
Insertion
Action
Cricothyroid (ELN)
arch of the cricoid cartilage
inferior border of the thyroid cartilage
draws the thyroid cartilage forward, lengthening the vocal ligaments, tenses vocal cords
Thyroarytenoid (vocalis, ILN)
inner surface of the thyroid cartilage
lateral border of the arytenoid cartilage
relaxes and adducts the vocal folds
Lateral cricoarytenoid (ILN)
muscular process of the arytenoid cartilage
Adducts the vocal cords by rotating the arytenoid cartilage
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Muscles controlling Movements of the Vocal Cords
ELN –ext laryngeal branch from SLN(CN X)
ILN –inferior laryngeal nerve from RLN (CN X)

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33. Muscles Controlling Movements of the Vocal Cords
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Intrinsic Muscles
Origin
Insertion
Action
Posterior cricoarytenoid (ILN)
posterior surface of the lamina of the cricoid cartilage
muscular process of the arytenoid cartilage
Abducts the vocal cords by rotating the arytenoid cartilage
Interarytenoid m., transverse (ILN)
posterior surface of the arytenoid cartilage
posterior surface of the contralateral arytenoid cartilage
Closes posterior part of rima glottidis by approximating arytenoid cartilages
Muscles controlling Movements of the Vocal Cords
ELN –ext laryngeal branch from SLN(CN X)
ILN –inferior laryngeal nerve from RLN (CN X)

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35. Mucous Membrane
Stratified squamous epith.: over vocal cords and upper part of vestibule of larynx
Ciliated columnar epith.: remainder of the cavity
Mucous glands:
Ventricles and sacculi
Posterior surface of epiglottis
Margins of aryepiglottic folds
Reinke’s layer of connective tissue: No glands and no lymph vessels
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Margins of aryepiglottic folds – none on he free edges of the vocal cords
Reinke’s layer of connective tissue – lies immediately under the epith. Of larynx and superficial to elastic layer. NO GLANDS BENEATH AND NO LYMPH VESSELS IN IT.

36. Vocal Folds
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37. Nerve Supply Supplied by Vagus nerve: Superior laryngeal n.
Internal branch (sensory) – areas above the glottis
External branch (motor and sensory)
Motor – Cricothyroid muscle
Sensory – Anterior infraglottic larynx at level of cricothyroid membrane
Inferior (recurrent) laryngeal n.
Motor – all intrinsic laryngeal muscles of SAME side (except cricothyroid) and interarytenoid muscle of BOTH sides
Sensory – areas below the glottis
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RLN – longer course on L than R, L: turns around arch of aorta, R: around subclavian artery
Nucleus ambiguus – somatic motor nucleus of CN IX, X, XI
- supplied by PICA (fr. Veterbal a.) and AICA (fr. Basilar artery)

38. Blood Supply Upper Larynx Lower Larynx External carotid artery
Superior thyroid artery
Superior laryngeal artery
Lower Larynx
Subclavian artery
Thyrocervical artery
Inferior thyroid artery
Inferior laryngeal artery
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39. Venouos Drainage Upper Larynx Lower Larynx Superior laryngeal vein
Superior thyroid vein
Internal jugular vein
Lower Larynx
Inferior laryngeal vein
Inferior thyroid vein
Innominate vein
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40. Lymphatic Drainage Main: Deep Cervical group L.N. Supraglottic area
98%: Pedicle Ant. End of aryepiglottic fold -> pass laterally and leave the larynx through the thyrohyoid membrane ->Upper deep cervical nodes (bet. Digastric tendon and omohyoid muscle)
2%: Lower cervical chain or spinal accessory chain
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Generally, Lymg drainage from each half of larynx is SEPARATE, LITTLE CROSSOVER/MIXING, although it does cross the midline in supra- and infra-glottic areas.
Contralateral drainage more likely in INFRAGLOTTIC areas; ergo, less consistent patterns of mets.
Lymphatics arising from larynx drain mainly into deep cervical LN
Vocal cord contain SCARCELY any lymphatic channels

41. Lymphatic Drainage Infraglottic area – 3 pedicles
1. Anterior pedicle -> cricothyroid membrane -> prelaryngeal (Delphian) nodes ->deep inferior cervical nodes
2. 2 Posterolateral pedicles -> cricotracheal membrane -> paratracheal chain/others to inferior jugular chain
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42. Physiology For more presentations in ENT, visit www.nayyarENT.com
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43. Basic Functions Protection Respiration Phonation Fixation of chest
Closure of glottis
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Closure of glottis – helps to increase intrathoracic and intraabdominal pressure and aids in lifting, digging, defecation, vomiting, urination or childbirth

44. Protection Acts as a sphincter Closure of the laryngeal inlet
Closure of the glottis
Cessation of respiration
Cough relfex, expulsion of secretions and foreign bodies
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Prevents entrance of ANYTHING but AIR into the lung

45. Protection 3 Sphincteric tiers of airway protection:
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3 Sphincteric tiers of airway protection:
Contraction of superior division of the thyroarytenoid muscles
Contraction of middle thyroarytenoid fibers
Contraction of inferior division of thyroarytenoid
Unilateral SLN paralysis may lead to aspiration (failure of ipsilateral cord closure) despite integrity of both RLNs
*(one SLN DOES NOT produce simultaneous activation of the contralateral adductor musculature)
3 Sphincteric tiers of airway protection:
1.Contraction of superior division of the thyroarytenoid muscles contained in the aryepiglottic folds
2.Contraction of middle thyroarytenoid fibers in false cords
3.Contraction of inf. Division of thyroarytenoid at the level of true cord (MOST SIGNIFICANT barrier to aspiration owing to the upturned border of the cord margin)
SLN stimulation – produces strong laryngeal ADDUCTOR response and inhibition of laryngeal abductor activity, resulting in various degrees of reflex apnea.
Laryngeal spasm – mediated solely by SLN

46. Respiration
Assists in regulation of gaseous exchange with the lung and maintenance in acid-base balance
Glottis opens a fraction of a second before air is drawn in by descent of the diaphragm
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Posterior cricoarytenoids
Phasic inspiratory abduction
Synchronous w/respiration
Cricothyroid muscle
Phasic inspiratory contraction/adduction
Increases AP diameter of glottic chink
By active muscular dilatation of the laryngeal aperture – meaning by opening of the glottis, which occurs with rhythmic bursts of activity of RLN.
Phasic inspiratory abduction – posterior cricoarytenoids – synchronous with respiration
Phasic inspiratory contraction – cricothyroid m. (vocal cord adductor and isotonic tensor) –increases AP diameter of of glottic chink.
*both are driven by medullary respiratory center

47. Phonation in brief Voice produced by vibration of the vocal cords
Fundamental tone produced at the larynx
Modified by resonating chambers of the upper aerodigestive tract
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7/15/2012