Anatomy and Physiology of Larynx Ranin Omar ,Shaima Alsosary and Nada Alotaibi

-The larynx starts from the 3rd to 6th cervical vertebrae. -It moves vertically and in anteroposterior direction during swallowing. -It can also be passively moved from side to side producing a grating sensation called laryngeal crepitus.

Corniculate (Santorini) Laryngeal Cartilages 3 paired 3 single Arytenoid It is pyramidal in shape. It has a base which articulates with cricoid cartilage, and an apex which supports the corniculate cartilage. Epiglottis It is a leaf-like. It is attached to body of hyoid Corniculate (Santorini) Thyroid It is the largest.its anteriorly forming an angle. Vocal cords are attached to the middle of thyroid angle. Most of laryngeal foreign bodies are arrested above the vocal cords. Cuneiform (Wrisberg) Cricoid It is the only cartilage forming a complete ring. the posterior part is a lamina while anteriorly it is arch.

Thyroid, cricoid and most of the arytenoid cartilages are hyaline cartilages whereas epiglottis, corniculate, cuneiform and tip of arytenoid near the corniculate cartilage are elastic fibrocartilage

LARYNGEAL JOINTS

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

Intrinsic

MUSCLES OF LARYNX •They are of two types :  Intrinsic which attach laryngeal cartilages to each other.  Extrinsic :which attach larynx to the surrounding structures.

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

Laryngeal cavity

Laryngeal cavity Rima vestibuli Extends from laryngeal inlet to lower border of the cricoid cartilage Narrow in the region of the vestibular folds (rima vestibuli) Narrowest in the region of the vocal folds (rima glottidis) Divided into three parts: Supraglottic part, the part above the vestibular folds, is called the vestibule The part between the vestibular & the vocal folds, is called the ventricle Infraglottic part, the part below the vocal folds Rima glottidis A B C

Physiology of larynx

Function of larynx : 1-protection of lower airways 2-Phonation 3-Respiration 4-Fixation of the chest

protection of lower airways : Phylogenetically , this is the earliest function to develop ; voice production is secondary . The larynx protects the lower passages in three different ways : 1-sphincteric closure of laryngeal opening 2-Cessation of respiration 3-Cough reflex

Phonation Larynx is like a wind instrument .voice is produced by the following mechanism : 1 vocal cords are kept adducted 2-infraglottic air pressure is generated by the exhaled air from the lung due to contraction of thoracic and abdominal muscles 3-The air force open the cords and is released as small puffs which vibrate the vocal cords and produce sound which is amplified by mouth ,pharynx, nose and chest . this sound is converted into speech by the modulatory action of lips,tongue,palate,pharynx and teeth . Intensity of sound depends on the air pressure produced by the lung while pitch depends on the frequency with which the vocal cords vibrate

Respiration Larynx regulates flow of air into the lung .vocal cords abduct during inspiration and adduct during expiration .

Fixation of the chest When larynx is closed , chest wall gets fixed and various thoracic and abdominal muscles can then act best .this function is important in digging ,pulling and climbing . Coughing ,vomiting ,defaecation,micturition and child birth also require a fixed thoracic cage against a closed glottis .

Histology of larynx Mucosa False vocal cords: Pseudostratified ciliated columnar epithelium True vocal cords: Non Keratinized stratified squamous epithelium Intrinsic Muscles Cartilages - Larger Laryngeal Cartilages (Hyaline)

Lymphatic drainage of larynx Supraglottic larynx “above vocal cord” drained into upper deep cervical nodes Infraglottic larynx “below vocal cords” drained into prelaryngeal and pretracheal nodes then to lower deep cervical and mediastinal nodes There is no lymphatic in vocal cords

Nerve supply of larynx Motor : All muscles supplied by recurrent laryngeal nerve except cricothyroid muscle which supplied by external laryngeal n(branch of superior laryngeal n) Sensory : above vocal cord :internal laryngeal nerve (branch of superior laryngeal) Below vocal cord :recurrent laryngeal nerve

Blood supply of larynx Arterial supply : Laryngeal branches of superior and inferior thyroid arteries. Venous drainage : Superior thyroid vein> internal jugular vein Inferior thyroid vein >brachiocephalic vien

Spaces of larynx 1-Pre-epiglottic space of boyer 2-Paraglottic space 3-reinke’s space

Embryological development Laryngeal mucosa : endoderm of cephalic part of forgeut Laryngeal cartilages and muscles: mesenchyme