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Anatomy and physiology of larynx
- 1. Anatomy and Physiology of Larynx Dr. Krishna Koirala 2019-03-18
- 2. • Situated in the midline neck between 3rd - 6th cervical vertebral level • Consists of a framework of cartilages, connected by ligaments and membranes, lined by a mucous membrane and moved by muscles
- 3. Anatomical components –Cartilaginous skeleton –Intrinsic muscles –Extrinsic muscles –Mucosal lining
- 15. Vocal fold
- 17. Vocal fold
- 18. Laryngeal Cartilages Single (3) Paired (3) Epiglottis Arytenoid Thyroid Corniculate (cartilages of Santorini) Cricoid ( Signet ring like cartilage) Cuneiform (cartilages of Wrisberg)
- 22. 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
- 27. Laryngeal cavity 1. Laryngeal inlet 2. Laryngeal Vestibule 3. Laryngeal Ventricle 4. Rima glottis 5. Subglottis
- 28. Membranes & Ligaments • Extrinsic – Connect thyroid cartilage & epiglottis with hyoid bone and cricoid cartilage with trachea • Intrinsic – Connect cartilages of larynx to each other – Alter the position, shape and tension of the vocal folds
- 29. Extrinsic • Thyrohyoid membrane • Hyoepiglottic ligament • Cricotracheal ligament
- 30. Intrinsic
- 31. 1. Quadrangular membrane Aryepiglottic ligament , Vestibular ligament 2. Crico-vocal membrane Vocal ligament ,Cricothyroid membrane 3. Thyroepiglottic ligament
- 32. Anatomical 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
- 33. A. Supraglottis - Epiglottis, Aryepiglottic folds ,Ventricular bands ,Laryngeal ventricle B. Glottis -True vocal cords , Anterior commissure, Posterior commissure C. Subglottis
- 34. Intrinsic Muscles A. Acting on vocal cords • Abduction Posterior crico - arytenoid • Adduction Lateral crico-arytenoid Transverse inter-arytenoid Thyro-arytenoid externa • Tension + lengthening Cricothyroid • Relaxation + shortening Vocalis
- 35. B. Acting on laryngeal inlet Opener Thyroepiglottic Closer Oblique inter-arytenoid, Aryepiglottic
- 36. Extrinsic Muscles • Primary Elevators Secondary Elevators Stylopharyngeus Mylohyoid Salpingopharyngeus Stylohyoid Palatopharyngeus Geniohyoid Thyrohyoid Digastric • Depressors – Sternohyoid Sternothyroid Omohyoid
- 40. Cricothyroid
- 41. Thyroarytenoid externa + Vocalis
- 46. Shape of Glottis
- 47. Shape of Glottis Quiet Respiration Forced Inspiration
- 48. Inspiration
- 49. Shape of Glottis Normal voice Whisper
- 50. Normal phonation
- 51. Whisper
- 52. 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
- 53. 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
- 54. Blood Supply • Arterial supply – Laryngeal b/o of superior & inferior thyroid • Venous drainage – Superior thyroid vein internal jugular vein – Inferior thyroid vein innominate vein
- 55. 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
- 56. 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
- 57. Protection of lower airway • 3-level below-upward closure (Tier Mechanism) – Vocal cords – Ventricular bands – Aryepiglottic folds • Cessation of respiration – Mediated by glossopharyngeal nv & deglutition centre • Cough reflex
- 58. 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
- 59. Voice Production
- 60. Theories of voice production • Puff Theory – Puffs of air emitted through glottis – Puffs of air set up vibratory activity of glottis • Neurochronaxic Theory – Each vibratory cycle initiated by nerve impulse to vocalis muscle via recurrent/vagus nerve – Frequency of voice dependent upon rate of impulses delivered • Aerodynamic Myoelastic Theory
- 61. Voice generation • Aerodynamic myoelastic theory – Vocal cords kept approximated Subglottic blast of air opens vocal cords from below upwards & causes their passive vibration, producing sound Bernoulli's effect closes vocal cords below upwards Cycle repeated
- 62. Aerodynamic myoelastic theory (opening phase)
- 63. Aerodynamic Myoelastic theory (closing phase)
- 64. Voice generation High pitch = short, thin, tense less elastic vocal cords Low pitch = long, bulky, relaxed, More elastic vocal cords Falsetto voice = tense vocal cords with small phonatory gap
- 65. Falsetto voice
- 66. Chest fixation • Closure of glottis helps in raising intra-thoracic & intra-abdominal pressure required for coughing , vomiting , defecation, micturition ,climbing , weight- lifting , labour etc.