By Dr. Adel Sahib Al-Mayaly Department of Surgery-Otolaryngology

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 Paired Unpaired Arytenoid Thyroid Corniculate It is made up of 9 cartilages:- 3 paired & 3 unpaired Paired Unpaired Arytenoid Thyroid Corniculate Cricoid Cuneiform Epiglottis

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.