1 Laryngeal Histopatholgy

2 Development of voice Birth: -larynx has higher anatomical position -6th level of the cervical region -pitch of neonate= 700 Hz 2 years: -soft cartilage's & lax ligaments (susceptible to collapse) -ossification of hyoid bone

3 5 years: -larynx assumes position C 7 -pitch decreases 20 years: -hardening of the cricoid 30 years: -hardening of the arytenoid 65 years: -ossification of all cartilage's except the cuneiform & corniculate

4 Four voicing signals in the neonate Birth Signal- -short duration (1 sec.)- vowel pattern Pain Signal- -long in duration, high-pitched -strained harsh quality Hunger signal- -rising & falling of pitch; glottal signal Pleasure Signal- -more nasal, pitch variability, glottal quality

5 Differences: Female & Male voices Prepubescent- -minimal, similar pitch Puberty- -females v.f.’s 4mm & male 8-10mm -thyroid angle is 120 °in females & 90 ° in males -v.f.’s enlarge & epiglottis flattens in both female & male -v.f. mucosa becomes less transparent -tonsils & adenoids atrophy

6 Geriatric vocal folds Deterioration in pitch, loudness range,& endurance v.f.’s appear thin & bowed “aging larynx”= Presbylaryngeus Breakdown of collagenous & elastic fibers Intermediate layers of v.f.’s are looser & thinner Bowed appearance during glottal closure Thickening of superficial layer of lamina propria.

7 Vocal Fold Microstructure Membranous portion of v.f.’s is intricate & layered, There are 5 histologically discrete layers, Layers vary in composition and mechanical properties,

8 Histologic Layers 5 histologic layers from most superficial to most deep are: –epithelium –lamina propria (3 layers) superficial layer intermediate layer deep layer vocalis muscle

9 Epithelium Lamina Propria superficial layer intermediate layer deep layer Vocalis Muscle Vocal Ligament

10 Frontal section through membranous portion epithelium lamina propria -superficial -intermediate -deep vocalis muscle conus elasticus epithelium lamina propria -superficial -intermediate -deep vocalis muscle conus elasticus

11 Epithelium Thin mucosal covering of squamous cells Wraps around internal contents of v.f.’s No mass, totally compliant Needs thin layer of mucous lubrication to ossilate best.

12 Lamina Propria Consists of three layers: superficial layer- -composed of loose fibrous matrix (known as Reinke’s space) -composition described as soft gelatin -intermediate layer- intermediate layer- -composed of elastic fibers and has slightly more mass

13 deep layer- –Denser still, composed of collagenous fibers Tissues of 3rd & 4th layers together are known as the vocal ligament The vocal ligament develops throughout childhood until the larynx reaches full maturity (puberty)

14 Vocalis Muscle Fifth layer Main body of the vocal fold Provides stability and mass

15 5 layers Layers change from superficial to deep, mass gradually changes & compliance Epithelial; most elastic Subsequent layers form a complex transition Finally, stiff deep muscle tissue

16 The Body-Cover Model Theory developed by Hirano (1974) Model explains extreme variability in voice production Model explained: -Cover :(epithelium & superficial layer of the lamina propria) -Transition:(intermediate and deep layer of the lamina propria) -Body : (vocalis muscle)

17 Cover: 1)epithelium 2) lamina propria -superficial Transition intermediate deep Body vocalis muscle

18 More on Body-Cover Characteristics of v.f. vibration dependent on: -length -elastic properties -mass distribution body contraction/ vocalis contraction= the cover becomes shortened and thicker giving more mass to the length unit cover is entirely passive; longitudinal state is specified by its length & lateral displacement depends on the thickness of its body.

19 Some clinical observations CT and vocalis activity are weak: movement of body & cover are identical, Vocalis activity is strong and the CT is weak: movement is greater for the cover rather than body, CT is active and vocalis is relaxed: both the body & cover are equally stiffened, movement is minimal (e.g. Falsetto).

20 Laryngeal Histopathology Before we speak of trauma to the structures of voicing, it is important to know the fine structures it is composed of, that which makes it vulnerable. We have talked about general categories of structure (i.e. cartilage’s & muscles)… ….Next is the histology of the larynx: The Tissue Structure.

21 Histology Cartilage's are made up of two different types of tissue Thyroid & Cricoid= Hyaline cartilage Epiglottis, cuneiform & corniculate= Elastic cartilage Hyaline: thin, dense collagenous fiber (protein based) Elastic: elastic fibers

22 Histological structure differences v.f. layered structure varies along length How does the membranous portion of the v.f. connect to the cartilaginous framework? -Anterior end: *macula flava (a mass of elastic fibers, attached to ant. commissure) -Posterior end: *post. macula flava (attached directly to arytenoid cartilage)

23 Function of Macula Flava Protects the membranous portion of the vocal folds during vibration from mechanical damage.

24 Structure in Newborns Epithelium is similar to adults Major difference: lamina propria is thick relative to its v.f. length (adult’s thinner) No vocal ligament

25 Vocal Fold Growth Immature macula flava in newborns (more susceptible to damage), Immature vocal ligament appears at 4 years (still very thin & does not contact vocalis muscle), 3 layers of lamina propria don’t exist until the ages 6-12, Thickness of cover and lamina propria increase with age, Intermediate lamina propria gets thinner with age, Deep layer of lamina propria gets thicker.

26 Summary: Thickness 1) Cover thickest at midportion 2) Lamina propria thinnest at midportion; lamina propria thickest at the two ends, ant. & post. macula flava 3) Vocalis muscle thicker than mucosa- thinner in the ant. end & thicker at post. end

27 Changes: Age 1) Cover gets thicker - not epithelium but superficial layer of lamina propria, 2) Superficial layer of lamina propria becomes swollen, 3) Elastic fibers become looser, especially in males 40 years and older, 4) Great individual differences in changes of v.f. structure.

28 Disorders: Cover, Transition & Body Epithelial Cover 1) Hyperplasia- atypical cell growth (squamous), either hypo- or hyper- dysplasia. Superficial layer of lamina propria 1) Vocal Fold Nodules- typically bilateral, edemous, white bumps, cover mass & thickness increase, develop on vocal fold edge, ant. 1/3.

29 Disorders Cont... 2) Vocal Fold Polyps- vocal fold edge, red or white, small or large, sessile or pedunculated, usually unilateral, asymmetrical, -Mass of cover increase -Cover stifness increase with bleeding & proliferation of collagenous fibers -Edema only, then decrease cover stiffness

30 Activity Clinical Execise: Tommy is a 13 year old boy who was in a car accident. He has several neurological deficits, as a result of a head injury. Tommy has limited movement of his abdominal muscles and external superior laryngeal nerve damage. He is currently in speech therapy with the following symptoms:

31 falsetto voice quality (high pitched, not due to prepubescent voice quality) cannot sit up in bed, however with support can be elevated to sitting position breathy quality voice (air escaping through vocal folds) all extrinsic and most intrinsic muscles are in tact. seems out of breath while speaking frequently takes recovery breaths complains of pain in and around his larynx

32 Questions? What muscles, cartilages are affected or damaged in the larynx and elsewhere in the body? Determine exact nerve and muscle involvement. Why is his pitch high, voice breathy? Why does he run out of air and have to take recovery breaths? What can we do for this patient? Prognosis for recovery?

33 Readings Ch. 3 Colton (Laryngeal Histopathology) Additional Reading: “Cover-Body- Theory of Vocal Fold Vibration” By Daniloff

34 Directed Reading

35 Directed reading summary Breathing apparatus is made up of: -pulmonary system (lungs & airways) -chest wall system (rib cage, abdomen & diaphragm) Pulmonary system is “passive”- no skeletal muscle Chest wall contains numerous skeletal muscles –rib cage: both insp. & exp. muscles –abdomen: expiratory muscles only –diaphragm: inspiratory muscle

36 Thoracic Expansion Vertical Transverse Anteriorposterior Diaphragm

37 Diaphragm/Abdominal Movement Diaphragm Abdominal Wall Inhalation Exhalation Pelvis

38 Relaxing Upright: Inspiration: 1) chest wall expands (lungs inflate) 2) diaphragm flattens, pushes abdominal contents outward (creating larger space in thoracic cavity) Expiration: 1) Gravity pulls down on rib cage (recoil) making it smaller 2) diaphragm recoils back to the dome shape 3) abdomen actively pushes contents back into place.

39 Supine: Inspiration: 1) driven by diaphragm, no abdominal involvement 2) rib cage has little elevation (fighting gravity) Expiration: 1) driven by recoil forces alone 2) abdomen expired by gravity

40 Speaking Upright: Inspiration: 1) accomplished by diaphragm 2) ribcage elevates (lungs inflate) 3) abdomen is active to “tune” the diaphragm by providing a relatively firm base to contract against Expiration: 1) Abdomen is main expiratory muscle 2) Abdomen pushes on the diaphragm & thus deflates lungs and generates pressure to speak on 3) rib cage also slowly descends with muscular help

41 Supine: Inspiration: 1) driven by the diaphragm 2) abdomen is non-active 3) rib cage expands against gravity Expiration: 1) driven by rib cage, recoil and muscular resistance allows us to speak 2) abdomen is nonactive (already in expiratory position)

42 Voice: Perception, Vibration, Myoelastic-Aerodynamic Theory, Bernoulli

43 Laryngeal Functions 1) Valving for life: 1. Breathing 2. Swallowing 3. Pressure activities (sneezing, coughing, lifting etc.) 2) Valving for speech: 1. Mechanics of voiceless sounds -Whispering & voiceless consonants 2. Mechanics of glottal vibration -vibratory cycle 3. Vibratory forces 3) Mechanics of voice control 1. Register 2. Pitch 3. Loudness 4. Quality

44 Valving: Life Breathing 1. Airway open (all three valves: false, true, supra cavity) 2. True open to different degrees -quiet respiration (intermediate position) -forced (lateral position)

45 Valving: Life Swallowing 1. Reflex mechanism: -pulls the larynx up against base of tongue & squeezes arytenoid cartilage's against epiglottis *this action closes laryngeal inlet to Supraglottal cavity & pulls esophagus open to receive bolus.

46 Valving: Life Pressure Activities 1. Sneezing, coughing, defecating, childbirth, lifting all require alveolar pressure) 2. Compression of air by respiratory pump & laryngeal valving to resist the escape of air 3. Need airway resistance to build pressure!

47 Valving: Speech General –requires modified use of laryngeal valve, –inherited a pressure reflex that has evolved for the unique requirements of speech, –v.f.’s adduct just enough to initiate vibration, –laryngeal resistance for voice is so refined that it can be controlled to produce changes in pitch & loudness from syllable to syllable.

48 Valving: Speech Mechanics of voiceless sounds 1. voiceless consonants- laryngeal valve is open, can be resisted by tongue, lips etc. 2. whispering- no voice, v.f.’s do provide resistance, -special whisper adjustment: vibrating glottal edges are stiff but do not touch (no vibration), the arytenoid cartilage's form a “glottal chink” (whisper triangle) to permit air to flow through glottis without v.f. vibration.

49 The Glottis- Whispering Whispering Triangle Muscular Glottis Cartilaginous Glottis

50 Valving: Speech Mechanics of glottal vibration 1. vibratory cycle- single vibration of the vocal folds, -”Begins when subglottal pressure (P s ) overpowers fold resistance just enough for the v.f. to first blow open.” *opening phase: v.f. continue to blow apart * closing phase: air escapes, reduces P s enough for fold resistance to overpower airflow, then close.

51 Glottal Cycle Arrows represent driving air pressure changes Notice that the vocal folds are always in transition opening phaseclosing phaseclosed phase open phase

52 Valving: Speech Mechanics of glottal vibration cont. 1. Two ratios to describe the features of vibration: * Speed quotient (SQ)- ratio of the durations of the opening phase to the closing phase (opening/closing). * Open quotient (OQ)- ratio of the duration of openness to the duration of the entire cycle (open/entire cycle)

53 Valving for speech cont... Mechanics of glottal cycle cont. 1. v.f.’s vary in compliance (how absorptive of force they are) & vary in complexity of vibratory movement * Vertical Phase Difference: v.f.’s open upward to outward; from bottom to top & back to front * Also, another vibratory complexity is the motion of the mucous membrane covering the true vocal folds.

54 Movement of vocal folds Note how the vocal folds open from bottom to top & back to front. Spread of glottal opening Vertical Phase difference Posterior Anterior Superior Inferior

55 Valving: Speech Vibratory Forces 1. Aerodynamic-myoelastic theory of phonation- “Glottal vibration is a result of the interaction between aerodynamic forces & vocal fold muscular forces.” *Aerodynamic forces- -Bernoulli Effect: as velocity of a gas or liquid increases, pressure decreases.

56 Bernoulli Effect Trachea & laryngeal airway as a freeway molecules of air= cars closer the molecules (cars), slower they move faster they move the farther apart they are spaced (lower pressure) faster air moves through glottis, farther molecules are apart & exert less force on v.f.’s Molecules Compressed molecular traffic

57 Valving: Speech Vibratory Forces cont. * Myoelastic Forces- -The opposing myoelastic (muscular & elastic tissue) forces provides the vertical phase difference essential for phonation.

58 * Myoelastic component cont.- 1) The glottal edge, particularly the loose mucosal covering functions as two separate but interconnected masses, one below the other, 2) These two masses are actually the upper & lower portions of the mucous membrane & the underlying vocalis muscle, 3) When lower portion is pushed aside by air pressure, the upper portion is dragged along, 4) The strength of the connection between these two masses is the mechanical coupling stiffness

59 Mechanical Coupling Stiffness Upper & lower portions work together (coupled), Remember: The masses are the vocal folds, One of several muscular forces involved with phonation. Upper Mass Lower Mass Upper Mass Lower Mass

60 Other muscular Forces All provide resistance to airflow- 1) Stiffness or “longitudinal tension”- inc. in muscle stiffness increases resistance; elongation merely thins vocalis muscle, 2) Mass resistance- thickness in vocalis muscle, more mass in folds the more force required to blow them apart, 3) Viscous forces- more viscous the folds, the more they decrease velocity of movement; inc.. resistance to aerodynamic forces

61 Summary of Aerodynamic-Myoelastic Theory “v.f. vibrations are dynamic interchanges of intraglottal pressure between the folds that force them apart and their mechanical resistance to this pressure.”

62 Summary Cont... Beginning of glottal cycle: 1) Intraglottal pressure exceeds atmospheric pressure above the folds & forces open a small glottal chink, 2) Air flows through the chink; molecules are slow in the trachea than increase velocity traveling through the glottis (i.e. Bernoulli slide), 3) Air molecules accelerate and start to move farther apart,

63 4) Pressure against upper portion of the folds decreases, but remains high against the lower portion (where molecules are still compressed in a “traffic jam”), 5) Therefore, the upper glottis is not blown open by pressure but “dragged” along by the stiffness of mechanical coupling, 6) Lower potion is where the intraglottal pressure forces the folds apart, 7) Aerodynamic force continues to open the glottis, 8) Closure when resistance exceeds intraglottal pressure.

64 Valving: Speech Mechanics of voice control- *Voice can be controlled for: 1) Pitch 2) Loudness 3) Quality 4) Register

65 Valving: Speech Mechanics of voice control- 1) Register: -The mode of adjustment of the larynx by which voice is produced. -Speech is produced almost always in one register, whereas singing many more. Three main registers: 1) modal 2) falsetto 3) pulse

66 Modal Register register used for speech produces low fund. frequencies (F o ) also called “chest” or “heavy” register vocal folds are short & thick stiffness low amplitude of vibration is large folds tend to completely close signal is rich in harmonics

67 Falsetto Register “light” register produces higher range of F o ’s vocalis is lax cricothyroid activity adjusts length longer, thinner, stiffer folds (compared to register) small amplitude of vibration incomplete closure of v.f.’s fewer higher harmonics shutter-like appearance

68 Pulse Register “vocal fry” or “glottal fry” low frequency register sounds rough or deep used infrequently for speech or singing short, thick & lax vocal folds complex vibratory pattern

69 Valving: Speech Mechanics of voice control cont.- 2) Pitch: -physical correlate is fundamental frequency, -Women’s F o = Hz; -Men’s F o = Hz -pitch is variable, -average F o changes during the first 20 years, than stabilizes.

70 Pitch: Vocal Fold Thickness Pitch is determined by rate of vibration, Male folds are longer & thicker, v.f. thickness changes correlate better to pitch than length, But...stiffness from lengthening is the main determiner of pitch. Low Pitch High Pitch

71 Valving: Speech Mechanics of voice control cont.- 3) Loudness: - Listener's response to the amount of energy in a sound. -Physical correlate = intensity, -Varies with volume & velocity of air, higher fundamental =greater loudness,

72 Loudness cont... Greater the volume velocity of each glottal pulse the greater the loudness, Intensity increases as alveolar and subglottal pressures increases, inc. air escapes Glottal resistance increases with intensity (pressure can not rise without an equal increase in resistance) Louder the tone, longer vocal folds stay closed.

73 Loudness Soft Loud volume velocity Alveolar pressure

74 Valving: Speech Mechanisms of voice control cont.- 4) Quality: -distinctive characteristics of a tone, exclusive of its pitch & loudness, -3 distinct qualities: 1) Breathiness 2) Harshness 3) Hoarseness

75 Breathiness Glottal adjustment offers enough resistance for vibration, Laryngeal adjustments: 1) in the front- v.f.’s close but don’t touch, however close enough to generate tone and... 2) in the back- glottal chink present which lets air escape to an excessive extent and... 3) excessively large glottal area in each cycle (large volume of air flow at low velocities) Folds barely close folds, low intensities

76 Harshness “roughness” Associated with “gravely” voice Cause is irregularity in v.f. vibration Frequency variability= “jitter” Amplitude variability= “shimmer”

77 Hoarseness Combines both breathiness & harshness Irregular vibratory patterns in which leakage is excessive Early warning sign of vocal pathology Aperiodic vibration

78 The End!!!