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Who am Ioooo. p. Anatomy & Physiology of Larynx Dr Sheetal Rai Dr Vijayalakshmi S Dept of ENT Yenepoya Medical College. Specific Learning Objectives Define the position and extent of the larynx Outline the structures forming the framework of the larynx
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Anatomy & Physiology of Larynx Dr Sheetal Rai Dr Vijayalakshmi S Dept of ENT Yenepoya Medical College
Specific Learning Objectives Define the position and extent of the larynx Outline the structures forming the framework of the larynx Outline the structure of cavity of the larynx Describe the lining of the interior of the larynx Describe the lymphatic drainage of the larynx Describe the nerve supply of the larynx
Specific Learning Objectives Define the spaces of the larynx List the differences between paediatric and adult larynx List the functions of the larynx
Laryngeal Cartilages 3 single & 3 paired Single Paired Epiglottis Arytenoid Thyroid Corniculate (Santorini) Cricoid Cuneiform (Wrisberg)
Thyroid Cartilage • Shield shaped, open posteriorly, angulated anteriorly • Angulation more acute in males • Its function is to shield larynx from injury and provide an attachment to vocal cords
Cricoid Cartilage • Signet ring shaped • Stronger than thyroid cartilage. • Lamina – 2 to 3 cm from above downwards, considerably broader than anterior arch.
Important from structural & functional point of view • Base for entire larynx • Support to arytenoid • Attachment to intrinsic muscles • Only part of cartilagenous framework that forms continuous 360 degree ring • Once injured or strictured , difficult to • resect while preserving • laryngeal function
Epiglottis • Thin leaf shaped fibro-cartilage, situated in midline • Upper free end broad & rounded, projects up behind base of tongue • Narrow base called petiole • This attachment forms lower limit of pre-epiglottic space
Arytenoids • Paired cartilages, pyramidal in shape • Base articulated with cricoid • PCA & LCA muscles attach on muscular process • Anterior angle elongated into vocal process which receives insertion of vocal ligament
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.
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 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
Reinke’s Space • Mucosa over the vocal ligament loosely attached to ligaments • Thus there is a submucosal space along most of the length of truer VC
Pre-Epiglottic Space • Bound sup by hyo-epiglottic ligament, ant by thyrohyoid memb. & thyroid cartilage and posteriorly by epiglottis • Filled with fat and areolar tissue • Continuous with para-glottic space • Cx of laryngeal surface of epiglottis readily spread to PreEpiSpace
Shape of Glottis Quiet Respiration Forced Inspiration
Shape of Glottis Normal voice Whisper