Anatomy & Physiology of Larynx Dr. Vishal Sharma

Larynx (anterior)

Larynx (posterior)

Larynx (posterior)

Larynx (lateral)

Larynx (superior)

Larynx (superior)

Larynx (sagittal section)

Larynx (sagittal section)

Larynx (coronal section)

Vocal fold

Vocal fold

Laryngeal Cartilages 3 single & 3 paired Single Paired Epiglottis Arytenoid Thyroid Corniculate (Santorini) Cricoid Cuneiform (Wrisberg)

Cartilages (anterior)

Laryngeal Cartilages

Cartilages (posterior)

Cartilages (posterior)

Cartilage Histology Elastic: Epiglottis, corniculate, cuneiform & apex of arytenoid. Little or no calcification. Hyaline: Thyroid, cricoid & remaining arytenoid. Calcify as age advances. Ossification begins by 25-30 yr & is completed by 60 yr.

Indirect Laryngoscopy

Flexible Laryngoscopy RIGHT LEFT

Laryngeal cavity 1. Laryngeal inlet 2. Laryngeal Vestibule 3. Laryngeal Ventricle 4. Rima glottis 5. Subglottis

Pediatric Larynx Conical in shape & subglottis is narrowest part Positioned high (C3-C4) Moves higher during swallowing allowing simultaneous breathing & feeding Loose sub-mucosal tissues (swell up easily) Soft cartilages that collapse easily

Membranes & Ligaments Extrinsic: connect thyroid cartilage & epiglottis with hyoid bone; cricoid cartilage with trachea. Intrinsic: connect cartilages of larynx to each other.

Extrinsic Thyrohyoid membrane Hyoepiglottic ligament Cricotracheal ligament

Intrinsic

Intrinsic

Intrinsic 1. Quadrangular membrane  Ary-epiglottic ligament  Vestibular ligament 2. Crico-vocal membrane  Vocal ligament  Cricothyroid membrane 3. Thyro-epiglottic ligament

Oncological Divisions A. Supraglottis: laryngeal inlet to apex of ventricle B. Glottis: apex of ventricle to 10 mm below C. Subglottis: lower glottic border to lower cricoid border

Subsites A. Supraglottis: 1. Epiglottis 2. Aryepiglottic folds 3. Ventricular bands 4. Laryngeal Ventricle B. Glottis: 1. True vocal cords 2. Anterior commissure 3. Posterior commissure C. Subglottis

Intrinsic Muscles A. Acting on vocal cords Abduction   Posterior crico-arytenoideus Adduction   Lateral crico-arytenoideus  Transverse inter-arytenoideus  Thyro-arytenoideus externa Tension + lengthening   Cricothyroid Relaxation + shortening   Vocalis

Intrinsic Muscles B. Acting on laryngeal inlet Opener   Thyro-epiglottic Closer   Oblique inter-arytenoideus  Ary-epiglottic

Extrinsic Muscles Primary Elevators Secondary Elevators  Stylopharyngeus  Mylohyoid  Salpingopharyngeus  Stylohyoid  Palatopharyngeus  Geniohyoid  Thyrohyoid  Digastric Depressors  Sternohyoid  Sternothyroid  Omohyoid

Posterior cricoarytenoid

Lateral cricoarytenoid

Transverse Inter-arytenoid

Cricothyroid

Thyroarytenoid externa + Vocalis

Oblique Inter-arytenoid

Spaces of Larynx

Reinke’s space

Pre-epiglottic space

Para-glottic space

Communications

Shape of Glottis

Shape of Glottis Quiet Respiration Forced Inspiration

Inspiration

Shape of Glottis Normal voice Whisper

Normal phonation

Whisper

Mucous Membrane Stratified squamous epithelium: Epiglottis (anterior surface + upper half of posterior surface), upper part of aryepiglottic folds & vocal cords Pseudo-stratified ciliated columnar (respiratory) epithelium: Rest of laryngeal mucous membrane

Nerve Supply Superior Laryngeal Nerve: Internal: sensation to supraglottis & glottis External: motor to cricothyroid muscle Recurrent Laryngeal Nerve: sensation to subglottis motor to all intrinsic muscles but cricothyroid

Blood Supply Arterial supply: Laryngeal br. of superior & inferior thyroid Venous drainage: Superior thyroid vein  internal jugular vein Inferior thyroid vein  innominate vein

Lymphatic Drainage Supraglottis: via thyrohyoid membrane into upper deep cervical nodes & thyroid gland Subglottis: via cricothyroid membrane into pretracheal + lower deep cervical nodes Glottis: has no lymphatics

Functions of Larynx 1. Protection of lower airway 2. Phonation (voice production) 3. Passage of air into lungs for respiration 4. Chest fixation by glottic closure

Protection of lower airway a. 3-level below-upward closure of:  vocal cords  ventricular bands  aryepiglottic folds b. Cessation of respiration: mediated by glossopharyngeal nv & deglutition centre. c. Cough reflex

Voice Production 1. Voice activating air reservoir in lungs: affects voice intensity 2. Voice generation: affects voice pitch 3. Voice resonation: affects voice quality 4. Voice articulation: affects voice quality

Voice Production

Neuro-chronaxic theory (?) Vibration of vocal fold muscles due to impulses generated from recurrent laryngeal nerves. Speed is regulated by acoustic center in brain. Obsolete theory because: muscle contraction not so fast to produce vibrations even paralyzed vocal folds can produce phonation passive phonation occurs in excised larynges

Combined Aerodynamic & Myoelastic theory Proposed by Jan Willem van den Berg in 1958 Vocal cords kept approximated  Subglottic blast of air opens vocal cords from below upwards & causes their passive vibration, producing sound  Muscle tension + Bernoulli's effect closes vocal cords below upwards  Cycle repeated

Aerodynamic myoelastic theory (opening phase)

Aerodynamic myoelastic theory (closing phase)

Stroboscopic examination

Voice generation  High pitch = short, thin, tense, less elastic vocal cords  Low pitch = long, bulky, relaxed, more  Falsetto voice = tense vocal cords, only edge of vocal fold vibrates & body is relaxed, with small phonatory gap

Falsetto voice

Vocal cord cross-section

Normal phonation

Falsetto voice

Glottis state in phonation Voiceless (full air stream) Breathy voice (murmur) Slack voice Modal voice: maximum vibration, sweet spot Stiff voice Creaky voice (restricted air stream) Glottalized (blocked air stream)

Glottis state in phonation

Vocal Registers Vocal fry register: lowest vocal register Modal voice register: commonly used for speaking & singing Falsetto register: one octave higher than modal voice register Whistle register: highest voice register. Used by female singers

Musical notes & octaves

Guinness World records Georgia Brown (2006): Highest vocal range from G2 to G10 Highest vocal note (G10) Adam Lopez (2002): Highest vocal note for male (C8) Tim Storms (2002): lowest vocal note (8 Hz = two octaves below lowest B on a piano)

Adam Lopez & Tim Storms

Voice resonation Oral & pharyngeal cavity  S Nasal cavity  M, N, Ng In rhinolalia clausa: M, N & Ng are uttered as B, D & G respectively In rhinolalia aperta: B, D & G are uttered as M, N & Ng

Organs of articulation

Places of articulation  Bilabial: both lips  Labio-Dental: lips + teeth  Dental: teeth + tip of tongue  Alveolar: alveolus + tip of tongue  Palatal: hard palate + tongue blade  Retroflex: tongue tip + hard palate  Velar: tongue base + soft palate  Glottal: produced in glottis

Places of articulation

Sound production  Bilabial  P, B, M, W  Labio-Dental  F, V;  Dental  T, D  Alveolar  T, D, N, L, S, Z  Palatal  Ch, Chh, J, Jh, Y  Retroflex  R, T, Th, D, Dh  Velar  K, Kh, G, Gh  Glottal  H, ?, uh-oh

Chest fixation Closure of glottis helps in raising intra-thoracic & intra-abdominal pressure required for: Coughing  Vomiting Defecation  Micturition Climbing  Weight-lifting Labour

Thank You