1. Anatomy of Phonation
Ch. 4

2. Spoken Communication
Voiceless phonemes or speech sounds- produced without the use of the vocal folds /s/, /f/
Voiced sounds are produced by action of the vocal folds /z/, /v/
Phonation is voicing, the product of vibrating vocal folds
Respiration is the energy source that permits phonation to occur

3. Vocal Folds
Made up of five layers of tissue with the deepest layer being muscle
Space between the vocal folds is glottis
Area below the vocal folds is subglottal region
Alternately produce /a/ and /h/- you should feel the vocal folds vibrate and then stop

4. Functions of the Larynx
Phonation
Sphincter-vocal folds are capable of a strong and rapid clamping of the airway to keep foreign objects out
Hold your breath
Lifting heavy objects/Childbirth- “fix” or anchor your larynx which provides muscles of upper body a solid framework

5. Framework of Larynx A musculocartilaginous structure
Comprised of three unpaired and three paired cartilages bound by ligaments and lined with mucous membrane
Oddly shaped box that sits atop the last ring of the trachea
Adjacent to cervical vertebrae 4-6 in the adult
Average length is 44mm- males, 36 mm- females

7. Cavities of Larynx Aditus- entry to the larynx
Vestibule- space between the aditus and the ventricular folds (false vocal folds)
Laryngeal ventricle- middle space of the larynx
Lies between the margins of the false vocal folds and true vocal folds
False vocal folds- not used for phonation except in rare cases
Lateral walls are comprised of the aryepiglottic folds
Laryngeal ventricle- Contains the laryngeal saccule which has more than 60 mucous glands that secrete lubricating mucous into the laryngeal cavity

8. Cricoid Cartilage Complete ring resting atop the trachea
Most inferior of the laryngeal cartilages
Posterior quadrate lamina- provides point of articulation for arytenoid cartilages
Lateral surface- point of articulation for inferior horns of thyroid cartilage
Cricothyroid joint- diathrodial, pivoting joint permits rotation of the two structures
Would fit loosely on your little finger

9. Thyroid Cartilage Unpaired cartilage Largest of the cartilages
Articulates with the cricoid cartilage below
Paired processes allow it to rock forward and backward
Prominent anterior surface made of two places- thyroid laminae
Joined at the midline- thyroid angle
Superior most point is the thyroid notch (adam’s apple)

10. Thyroid Cartilage
Vocal folds attach to the thyroid just behind the thyroid notch
Posterior aspect is open- two prominent sets of cornu or horns
Inferior cornu project downward to articulate with the cricoid cartilage
Superior corner project superiorly to articulate with the hyoid

11. Arytenoid Cartilages
Ride on the high-backed upper surface of the cricoid cartilage
Form the posterior point of attachment for the vocal folds
Paired cartilage
Vocal processes project anteriorly toward thyroid notch, posterior portion of the vocal folds attach
Muscular process forms the lateral outcropping of the arytenoid pyramid- point of attachment for muscles that adduct/abduct the vocal folds

12. Corniculate Cartilage
Corniculate cartilages
Ride on the superior surface of each arytenoid cartilage
Prominent landmarks in the aryepiglottic folds

13. Epiglottis Unpaired cartilage
Leaf-like structure arises from the inner surface of the thyroid cartilage just below the notch
Attached by the thyroepiglottic ligament
Sides are joined with the arytenoid cartilages via the aryepiglottic folds
Projects upward beyond the larynx and above the hyoid bone

14. Epiglottis
Attached to the root of the tongue by glosso-epiglottic fold and lateral glosso- epiglottic ligamets
This juncture produces the valleculae
Pyriform sinuses- lateral recesses
Attached to the hyoid bone via the hyoepiglottic ligament
Surface is covered with a mucous membrane lining

15. Cuneiform cartilages
Small cartilages embedded within the aryepiglottic folds
Situated above and anterior to the corniculate cartilages
Provide support for the membranous laryngeal covering

16. Hyoid Bone
Provides the union between the tongue and the laryngeal structure
Unpaired small bone
Articulates loosely with the superior cornu of the thyroid cartilage
U-shaped, being open in the posterior side
Corpus or Body- forms the front of the bone, point of attachment for six muscles
Greater cornu- lateral surface of the corpus projecting posteriorly
Lesser cornu-found at the junction of the corpus and greater cornu

17. Extrinsic ligaments
Thyrohyoid membrane- stretches between the greater cornu of the hyoid and lateral thyroid
Lateral Thyrohyoid ligament- superior cornu of the thyroid to posterior tip of the greater cornu hyoid
Median Thyrohyoid ligament- from corpus hyoid to upper border of the anterior thyroid
Together- these three connect the larynx and the hyoid bone

18. Extrinsic ligaments
Hyoepiglottic ligament/Thyroepiglottic ligament- attach the epiglottis to hyoid and inner thyroid cartilage, just below the notch
Cricotracheal ligament- attaches the trachea to the larynx

19. Intrinsic ligaments Quandrangular membranes
Connect the cartilages of the larynx and form the support structure for the cavity of the larynx and vocal folds
Quandrangular membranes
Layer of connective tissue running from the arytenoids to the epiglottis and thyroid cartilage
Form false vocal folds
Originate at inner thyroid angle and sides of epiglottis and form an upper cone that narrows and terminates at the arytenoid and corniculate cartilages

20. Intrinsic ligaments Aryepiglottic muscles
From the side of the epiglottis to the arytenoid
Form the upper margin of the quadrangular membrane
Form the aryepiglottic folds
Folds are simply the ridges marking the highest elevation of these membranes
Pyriform sinus is the space between the aryepiglottic fold and the thyroid cartilage

21. Vocal Fold Structure
Most superficial layer- protective layer of epithelium
Glistening white appearance
Protective layer
Second layer- superficial lamina propria (SLP)-
elastin fibers
Stretched
cushions
Third layer- Intermediate lamina propria (ILP)-
elastin fibers running in an A-P direction
provide elasticity and strength

22. Vocal Fold Structure Fourth layer- Deep lamina propria (DLP)-
Collagen fibers that prohibit extension
ILP and DLP combine to make up the vocal ligament
Stiffness and support
Fifth layer-Thyroarytenoid muscle-
active element of the vocal folds
Mucosal lining- combination of the epithelial lining and first layer

23. Movement of the Cartilages
Cricothyroid and Cricoarytenoid joints are the only functionally mobile points of the larynx
Cricothyroid joint- junction of cricoid cartilage and inferior cornu of the thyroid cartilage
Diarthrodial (synovial) joint that permit the cricoid and thyroid to rotate and glide
Rotation permits the thyroid cartilage to rock down in front
Permits the thyroid cartilage to glide forward and backward slightly
Provides the major adjustment for change in vocal pitch

24. Movement of the Cartilages
Cricyarytenoid joint
Formed between the cricoid and arytenoid cartilages
Synovial joints permit rocking, gliding and minimal rotation
Rocking action permits two vocal processes toward each other permitting the vocal folds to approximate
Arytenoids glide on the long axis which changes vocal fold length
Arytenoids rotate upon a vertical axis which permits abduction

25. Intrinsic Laryngeal Muscles
Have both origin and insertion on laryngeal cartilages
Make fine adjustments to the vocal mechanism
Assume responsibility for opening, closing, tensing, lengthening and relaxing the vocal folds
Movement of the vocal folds into and out of approximation is achieved by the coordinated effort of many of the intrinsic muscles of the larynx
Changing pitch is reflected by a change in mass or tension

26. Intrinsic Laryngeal Muscles
Lateral Cricoarytenoid Muscle
Attaches to the cricoid and the muscular process of arytenoid
Muscular process will be drawn forward
Rocks the arytenoid inward and downward
Adduction of vocal folds
Lengthens the vocal folds
Innervated by X vagus nerve

27. Intrinsic Laryngeal Muscles
Transverse Arytenoid Muscle
Runs between the two arytenoid cartilages on the posterior surface
Pulls the two arytenoids closer together
Approximates the vocal folds
Increased medial compression which is increased force of adduction
Vital element in vocal intensity change
Innervation by the Recurrent laryngeal nerve of the X vagus

28. Intrinsic Laryngeal Muscles
Oblique Arytenoid Muscles
Paired muscles
Originate at the posterior base of the muscular process and course obliquely up to the apex of the opposite arytenoid
Form an “X”
Pull the apex medially
Promotes adduction
Enforces medial compression
Rocks arytenoid and vocal folds down and in
Aids in pulling the epiglottis to cover the opening to the larynx
Innervation- Recurrent laryngeal nerve of the X Vagus

29. Intrinsic Laryngeal Muscles
Posterior Cricoarytenoid muscle
Sole abductor of the vocal folds
Originates from the posterior cricoid lamina
Project up to insert into the posterior aspect of the muscular process of the arytenoid cartilage
Pulls muscular process posteriorly
Rocks the arytenoid cartilage
Abducts the vocal folds

30. Intrinsic Laryngeal Muscles
Cricothyroid Muscle- composed of two heads
Pars Recta- originates on the anterior surface of cricoid cartilage and courses up to the lower surface of the thyroid lamina
Pars oblique- arises from the lateral cricoid cartilage to the point of juncture between the thyroid laminae and inferior horns
Both tense the vocal folds
Together they are the major contributors for pitch change
Innervated by the Superior Laryngeal Nerve of the X Vagus

31. Intrinsic Laryngeal Muscles
Pars Recta
Rocks the thyroid cartilage downward
Brings thyroid and cricoid closer together in front
Makes the posterior cricoid more distant from the thyroid
Vocal folds are stretched
Pars Oblique
Thyroid slides forward
Tense the vocal folds

32. Intrinsic Laryngeal Muscles
Thyrovocalis Muscle (abbreviated as vocalis)
Medial muscle of the vocal folds
Originates from the inner surface of the thyroid cartilage
Inserts into the lateral surface of the arytenoid vocal process
Contraction draws the thyroid and cricoid cartilages farther apart in front
Glottal tensor- tenses the vocal folds
Innervated by the Recurrent Laryngeal Nerve of the X Vagus

33. Intrinsic Laryngeal Muscles
Thyromuscularis Muscle
Paired muscle
Immediate lateral to each vocalis muscle
Originates on the inner surface of the thyroid cartilage near the notch
Inserts into the arytenoid cartilage at the base
Laryngeal relaxer
Relaxes the vocal folds
Innervated by the Recurrent Laryngeal Nerve

34. Extrinsic Laryngeal Muscles
Muscles with one attachment to a laryngeal cartilage
Laryngeal elevators- muscles that elevate the hyoid and larynx
Laryngeal depressors- those that depress the hyoid and larynx

35. Elevators Digastricus- two separate bellies- elevates the hyoid
Anterior-
originates on the inner surface of the mandible near the point of fusion
Inserts into hyoid
hyoid draws up and forward.
Innervated by the V Trigeminal
Posterior –
originates on the mastoid process of the temporal bone and
inserts into the hyoid at the juncture of the hyoid corpus and greater cornu
hyoid draws up and back.
Innervated by the the VII facial

36. Elevators Stylohyoid Muscle
Originates on the styloid process of the temporal bone
Courses down and inserts into the corpus of the hyoid
Elevates and retracts the hyoid bone
Innervated by the VII facial nerve

37. Elevators Mylohyoid Muscle Originates on the underside of the mandible
Courses to the corpus hyoid
Fanlike muscle
Forms the floor of the oral cavity
Innervated by the V trigeminal nerve

38. Elevators Geniohyoid Superior to the mylohyoid
Projects in a course parallel to the anterior belly of the digastricus from the inner mandibular surface down to the hyoid bone at the corpus
Elevates the hyoid and draws it forward
Innervated by the XII hypoglossal nerve arising from the first cervical spinal nerve

39. Elevators Hyoglossus Muscle Laterally placed muscle
Originates from the superior surface of the greater cornu of the hyoid and
inserts into the side of the tongue
Innervated by the the XII hypoglossal

40. Elevators Genioglossus Muscle Hyoid elevator and tongue depressor
Originates on the inner surface of the mandible and then down
insert into the tongue and anterior surface of the hyoid corpus
Innervated by the XII hypoglossal

41. Elevators Thyropharyngeus Muscle-
Originates from the thyroid lamina and courses up
Inserts into the posterior pharyngeal raphe
Elevates the larynx
Constricts the pharynx
Innervated by the RLN of the X Vagus

42. Depressors Sternohyoid muscle
Runs from the sternum to the inferior margin of the hyoid
Depresses the hyoid
Fixes the hyoid and larynx
Lowering is clearly evident following the pharyngeal stage in swallowing
Innervated by the ansa cervicalis

43. Depressors Omohyoid Muscle Has two bellies
Superior belly terminates on the side of the hyoid corpus
Inferior belly has its origin on the upper border of the scapula
Passes deep to the sternocleidomastoid
Depresses the hyoid bone and larynx
Innervated by the ansa cervicalis

44. Depressors Sternothyroid muscle Depresses the thyroid cartilage
Originates from the sternum and first costal cartilage
Inserts into the oblique line of the thyroid cartilage
Innervated by fibers of the spinal nerves

45. Depressors Thyrohyoid muscle
Originates from the thyroid cartilage to the
Inserts into the inferior margin of the greater cornu of the hyoid bone
Depress the hyoid or raises the larynx
Innervated by the spinal nerve

46. Laryngeal Stability Stability is the key to control
Gained through the development of the infra and suprahyoid musculature
Larynx is intimately linked via the hyoid bone, to the tongue
Movement of the tongue is translated to the larynx

47. Vocal Fold Paralysis
Most frequent cause- damage to the nerve during thyroid surgery or carotid surgery, blunt trauma, CVA, or aneurysm
One side of the Recurrent Laryngeal Nerve is damaged (lower motor neuron)- unilateral vocal fold paralysis
Bilateral nerve damage=Bilateral paralysis
Adductor paralysis-muscles of adduction are paralyzed and vocal folds remain in the abducted position
Abductor paralysis-cannot abduct the folds, respiration is compromised

48. Vocal Fold Paralysis
Damage to Superior Laryngeal nerve results in inability to alter pitch
Unilateral paralysis- one vocal fold is still capable of motion and phonation can still occur but it will be breathy
Bilateral adductor paralysis results in virtually complete loss of phonation