clinical anatomy and physiology of larynx
TRANSCRIPT
Dr.Ramesh Parajuli,MS Chitwan Medical College Teaching Hospital, Chitwan,
Nepal
• Laryngeal cartilages and membranes
• Laryngeal muscles: function
• 3 subdivisions of larynx
• Nerve supply of larynx
• Functions of larynx
Learning objectives
Anatomy of larynx
• Rigid skeletoncartilages, muscles, ligaments & membranes
• Extends from hyoid bone above to cricoid cartilage below
• Opposite to C3 to C6 cervical vertebra
• Laryngeal crepitus: absent in post-cricoid carcinoma
Laryngeal cartilages• 3 unpaired and 3 paired
cartilages
• Unpaired: 1. Thyroid2. Cricoid3. Epiglottis
• Paired: 1. Arytenoid 2. Cuneiform ( Wrisberg) 3. Corniculate (Santorini)
Histological types of laryngeal cartilages
(1) Elastic:
Epiglottis, corniculate, cuneiform & apex of arytenoid
Little or no calcification
(2) Hyaline:
Thyroid, cricoid & remaining arytenoid
Calcify as age advances
Ossification begins by 25 yr & is completed by 60 yr
1. Thyrohyoid membrane:2. Cricothyroid membrane:
cricothyrotomy
• Cricoid cartilage: only rigid & complete ring among the cartilages forming larynx and trachea
Cartilages (anterior)
Cartilages (posterior)
Laryngeal membranes
(I).Extrinsic membranes:1. Thyrohyoid membrane2. Cricothyroid membrane3. Cricotracheal membrane
(II).Intrinsic membranes:1. Cricovocal membrane forms vocal ligament2. Quadrangular membraneforms the vestibular
ligament
Larynx (sagittal section)
Larynx (coronal section)
NPL(Nasopharyngolaryngoscopy)
Vocal fold
Pediatric Larynx Vs Adult larynx
1. Subglottis is the narrowest part
2. Loose submucosal tissues (swell up
easily)
3. Positioned high (C3-C4)
4. Soft cartilages collapse easily
Subdivisions of larynx
A. Supraglottis: laryngeal
inlet to apex of ventricle
B. Glottis: apex of ventricle
to 1cm below
C. Subglottis: lower glottic
border to lower cricoid
border
Subsites
A. Supraglottis:
1.Epiglottis 2. AE fold 3. FVC 4. Ventricle
B. Glottis:
1.TVC 2. Anterior commissure 3. Posterior
commissure
C. Subglottis
Intrinsic Muscles
A. Acting on vocal cords
Abduction Posterior crico-arytenoid
Adduction Lateral crico-arytenoid
Transverse arytenoid (inter-arytenoid)
Thyro-arytenoid
Tension + lengthening Cricothyroid
Relaxation + shortening Vocalis ( internal part of thyroarytenoid)
B. Acting on laryngeal inlet
Opener Thyro-epiglottic (part of thyroarytenoid)
Closer Inter-arytenoid (oblique part)
Ary-epiglottic(Posterior oblique part of
interarytenoid)
Extrinsic laryngeal muscles
• Elevators of larynx
Primary elevators secondary elevators
Stylo-pharyngeus Mylohyoid
Salpingo-pharyngeus Stylohyoid
Palato-pharyngeus Geniohyoid
Digastric
• Depressors of larynx (strap muscles of the neck)
Sternohyoid ,Sternothyroid , thyrohyoid ,Omohyoid
Posterior cricoarytenoid
Lateral cricoarytenoid
Transverse Inter-arytenoid
Cricothyroid
Oblique Inter-arytenoid
Mucous Membrane
1.Stratified squamous epithelium
2.Pseudostratified ciliated columnar (respiratory)
epithelium
Nerve Supply
Superior Laryngeal Nerve (SLN):
• Internal: Sensory supply to supraglottis & glottis
• External: Motor supply to cricothyroid muscle
Recurrent Laryngeal Nerve(RLN):
• Sensory supply to subglottis
• Motor supply to all intrinsic muscles except
cricothyroid
Blood Supply
Arterial supply:
• Laryngeal branch of superior & inferior thyroid
artery
Venous drainage:
• Superior thyroid vein internal jugular vein
• Inferior thyroid vein innominate vein
Lymphatic Drainage
Supraglottis: Upper deep cervical nodes
Subglottis: Pretracheal + lower deep cervical nodes
Glottis: has no lymphatics
Functions of Larynx
1.Protection of lower airway: primary function
(i) Closure of larynx: three tier mechanism
(ii) Cough reflex
2.Phonation (voice production): secondary function
3.Respiration
4.Chest fixation by glottic closure: coughing,micturition,defecation
Thank you