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The Larynx Interesting synonyms of Larynx • Voice box, • Watch dog of tracheobronchial tree • Introduction • The larynx is an organ that provides a protective sphincter at the inlet of the air passages. • It is also responsible for voice production ; beside that it is a respiratory organ. • It is situated below the tongue and hyoid bone • and between the great blood vessels of the neck • It lies at the level of the fourth, fifth, and sixth cervical vertebrae. • • Skeleton of larynx Skeleton of larynx • It is made up of 9 cartilages:- 3 paired & 3 unpaired • Unpaired Paired Thyroid Arytenoid Cricoid Corniculate Epiglottis Cuneiform Thyroid cartilage Shield • The biggest cartilage & it encircles the laryngeal lumen. • It is made of 2 laminae of hyaline cartilages . • They join together anteriorly (Adam’s apple). • Diverge posteriorly. Thyroid cartilage Thyroid cartilage • Each lamina has superior, inferior & posterior borders. • There are 2 prolongations from the superior & inferior borders (thyroid cornu). • The inferior cornu articulates with cricoid to form cricothyroid joint (synovial joint). Thyroid cartilage • On each external surface of the lamina is an oblique line (for attachment of Muscles). Muscles attaching to the oblique line include • Sternothyroid muscle (insertion) • Thyrohyoid muscle (origin) • Inferior constrictor muscle (origin) Cricoid cartilage • like signet ring . • It is the only complete ring of cartilage in the walls of respiratory system. • It is made by lamina posteriorly & arch anteriorly. • The cricoid has two joints The epiglottic cartilage • leaf-shaped structure • It lies in the upper portion of the larynx. • prolonged below into a slender process (STALK or petiole). • attached in the midline to the back of the laryngeal prominence Arytenoid Cartilages • Each of the pair is a three-sided pyramid with anterolateral, medial and posterior surfaces. • The inferior base has • 1- forward projection, (vocal process); which provides attachment to the posterior end of the true vocal cords. Arytenoid Cartilages • • • • 2- Lateral projection, the muscular process. It provides attachment to:Posteriorly: posterior cricoarytenoid muscle Anteriorly: lateral cricoarytenoid muscle Arytenoid cartilages Articulations of Arytenoid cartilages • Cricoarytenoid Joint:• Is a synovial joint between the arytenoid cartilage and the lateral aspect of the lamina of the cricoid cartilage. • Cricothyroid joint:• Is a synovial joint between the lamina of cricoid & inferior thyroid cornu Interior of Larynx • The laryngeal cavity extends from the laryngeal inlet, through which it communicates with the • laryngopharynx, to the level of the inferior border of the cricoid cartilage. • 3 regions • 1-Supraglottis: from the tip of epiglottis to vocal cords. • 2- Glottis ((the vocal apparatus of the larynx) :area of vocal cords. • 3- Sub glottis:- from under surface of vocal cords to the 1st tracheal ring Arteries of Larynx • They are branches of the superior and inferior thyroid arteries. • 1- The superior laryngeal artery;-accompanies • the internal branch of the superior laryngeal nerve • 2- Inferior laryngeal artery:-accompanies the inferior laryngeal nerve (terminal part of the recurrent laryngeal nerve). • Veins of Larynx. • 1-The superior laryngeal vein:- usually joins the sup. thyroid vein • 2- The inferior laryngeal vein:- usually joins the inferior thyroid vein. Nerves of larynx The nerves of the larynx are the superior and inferior laryngeal branches of the vagus nerve 1-The superior laryngeal nerve:- from inferior vagal ganglion. The nerve divides into two terminal branches within the carotid sheath. 1- The internal laryngeal nerve(sensory & autonomic) Supply the mucosa above the vocal cords Nerves of larynx • 1- The external laryngeal nerve:- supplies the • 1- Cricothyroid muscle (external tensor of vocal cords). • 2- Inferior constrictor muscle. Inferior (Recurrent) laryngeal n. • It is the primary motor nerve of the larynx. • It supplies all the intrinsic muscles except the cricothyroid, • It also provides sensory fibers to the mucosa below the vocal cords. The vocal folds • The vocal folds are the sharp-edged folds of mucosa overlying the vocal ligaments and they are the source of the sounds (tone) that come from the larynx • Each vocal fold contains a:• 1- Vocal ligament, consisting of thickened elastic tissue. • 2- Vocalis muscle:-medial fibres of thyroarytenoid muscle.
