Clinical anatomy and physiology of larynx

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