Larynx

Dr: Azza Zaki

In The Name Of Allah The Merciful, The MercyGiving Dr: Azza Zaki

It is a respiratory organ ,which has the following functions: Voice production (phonation) forms a protective sphincter to the respiratory system. It maintains a patent airway. Position: It lies in the ant. neck at the levels of the bodies of C3- C6, from upper border of epiglottis to lower border of cricoid cartilage where Dr: Azza Zaki

it is continuous with the trachea.

The laryngeal skeleton consists of nine cartilages joined by ligament & membranes. Single cartilages:  Thyroid  Cricoid  Epiglottis Paired cartilages:  Arytenoid  corniculate  cuneiform. Dr: Azza Zaki

The thyroid cartilage consists of two laminae that fuse anteriorly to form the laryngeal prominence (Adam's apple). The angle that they make is usually more acute in males & is more prominent.  The post. border is drawn into sup. & inferior cornu. The inferior cornu articulate with the sides of the cricoid cartilage and form the cricothyroid joint. Azzaattachment Zaki  The oblique lineDr: for of the 

Is formed from a complete ring of hyaline cartilage.  It has a narrow anterior arch & a broad posterior lamina  It has 2 facets one for thyroid & the other for arytenoid.  All these joints are synovial. 

Dr: Azza Zaki

Is a leaf- shaped elastic cartilage situated behind the root of the tongue.  It is connected in front to the body of the hyoid bone (hyoepiglottic lig.) & by its stalk to the back of the thyroid (thyro-epiglottic ligament).  The sides of it are connected to the arytenoid cartilages by the aryepiglottic folds.  A median glossepiglottic & Dr: Azza Zaki 

They are pyramidal in shape They are situated on the upper border of the cricoid cartilage. It has an apex above & a base below.  The apex supports the corniculate cartilage. Two processes project from Dr: Azza Zaki

The base: The vocal process projects  forward& gives attachment to the vocal  ligament &the muscular process projects  laterally & gives attachment to the posterior & lateral cricoarytenoid muscles. Corniculate cartilage: Are 2 small nodules that articulate with the apices of the arytenoid cartilage. Cuneiform cartilages: Dr: Azza Zaki 

Extrinsic: 1)Thyrohyoid membrane:  Connects the upper margin of the thyroid cartilage to the body & greater cornu of the hyoid bone. In the midline the membrane is thickened to form median thyrohyoid lig.; the posterior border form lateral thyrohyoid lig.  It is pierced by the superior laryngeal vessels & the internal laryngeal nerve. Dr: Azza Zaki

2)Cricotracheal ligament: connects cricoid cartilage to the 1st tracheal ring. 3)Hyoepiglottic ligament & 4)Thyroepiglottic ligament. Intrinsic:The fibroelastic membrane lies beneath the mucous membrane. The quadrangular membrane: It extends between the epiglottis & the arytenoid cartilage. It is free at the top & bottom. The lower free margin forms the false vocal cord (or vestibular fold) & upper margin form aryepiglottic fold. Rima vestibuli: Dr: Azza Zaki Is the gap between the vestibular folds.

The cricothyroid ligament(or conus elasticus)cricovocal membrane: extends from the upper margin of the cricoid cartilage to attach to the back of the thyroid cartilage anteriorly and the arytenoid cartilage posteriorly.Its upper free margin is the vocal ligament (true vocal cord ( Rima glottidis: is the gap between the vocal folds in front (intermembranous part) & the vocal processes of the arytenoid (intercartilagenous part) behind Dr: Azza Zaki

It looks backward into the laryngeopharynx. The opening is bounded by:  The epiglottis,  The aryepiglottic fold,  The arytenoid cartilages  with corniculate cartilage on their apices  Cuneiform cartilage  The interarytenoid fold. Dr: Azza Zaki

The muscles can be divided into 2 groups: 1-Extrinsic Muscles: Because the hyoid bone is attached to the thyroid cartilage by the thyrohyoid membrane, its movement are accompanied by movements of the larynx. can be divided into: Elevators of the larynx: Digastric, stylohyoid,mylohyoid &geniohyoid (elevate hyoid) .Stylopharyngeus, palatopharyngeus ,Salpingopharyngeus & thyrohyoid (elevate thyroid). Depressor of the larynx: Sternothyroid, sternohyoid, omohyoid &elastic recoil of the trachea. Dr: Azza Zaki

Dr: Azza Zaki

The sphincter at the inlet: Is used during swallowing : The inlet is narrowed by the action of : 1- The oblique arytenoid: Bring aryepiglottic folds together 2-The aryepiglottic: pulls epiglottis posteriorly to arytenoid. So it prevent food from entering the larynx. Widening the inlet: By thyroepiglottic: Pulls aryepiglottic folds apart. Dr: Azza Zaki

The sphincters at the rima glottidus: adduction of the vocal cords: In phonation ,coughing, sneezing, &abdominal straining by :  Lateral cricoarytenoid  Transverse arytenoid: closes posterior part of rima glottidis by approximating arytenoid cartilages. Abduction of the vocal cord: by Posterior cricoarytenoid: by rotating arytenoid cartilage. Dr: Azza Zaki

Cricothyroid m.: They pull the thyroid cartilage forward& rotate it down relative to cricoid or they tilt the cricoid & arytenoid cartilages backward. These actions lengthen the vocal fold Vocalis:

Dr: Azza Zaki

Thyroarytenoid : It alters the pitch of the voice. Each muscle runs from the inner surface of thyroid angle to the anterolateral surface of the arytenoid . Some of the fibers may reach side of the epiglottis ( Thyro-epiglottic) Dr: Azza Zaki

Sphincteric function of the larynx: The 2 sphincters are at the inlet & at the rima glottidis. The sphincter at the inlet is used only during swallowing. The rima glottidis serves as a sphincter In coughing or sneezing In abdominal straining associated with Dr: Azza Zaki

Voice production: the intermittent release of expired air between the adducted vocal folds results in their vibration& the production of sound. The frequency or pitch of the voice is determined by changes in length & tension of the vocal lig.

Dr: Azza Zaki

It extends from the inlet to the lower border of the cricoid. It is divided into:  Upper part ( vestibule ): Extends from the inlet to the vestibular folds supplied by superior laryngeal vessels & internal laryngeal n The rima vestibuli: is the gap between the pink vestibular folds. The vestibular ligament: Dr: Azza Zaki is the thickened lower

Middle part of the larynx (glottic part): Extends from the level of the vestibular folds to the vocal folds. Vocal folds: are white as it is covered by stratified squamous epithelium & contain the vocal ligaments. It is the thickened upper edge of the cricothyroid lig. it stretches from the thyroid cartilage to the vocal process of the arytenoid. The rima glottidis: is the gap between the vocal folds in front & the vocal processes of the arytenoid cartilages behind. Dr: Azza Zaki

Sinus or ventricle of the larynx: A small recess on each side between the vestibular & vocal folds. A diverticulum ( the saccule) passes upward between the vestibular fold & the thyroid cartilage. The lower part (infraglottic): Extends from the level of the vocal folds to the lower border of the cricoid cartilage. It is supplied by the inferior laryngeal vessels & recurrent laryngeal nerve. Dr: Azza Zaki

Arterial supply:  To the upper half of the larynx is from the superior laryngeal branch of the superior thyroid artery.  To the lower half is by the inferior laryngeal branch of the inferior thyroid artery. Venous Drainage:  Superior laryngeal vein into superior thyroid vein  Inferior laryngeal vein into inferior thyroid vein. Lymph Drainage: Upper & lower halves to upper &lower deep cervical L.N. Few lymphatic drain Dr: Azza Zaki

The sensory nerve supply:  To the m.m above the vocal folds is from the internal laryngeal branch of the superior laryngeal branch of the vagus.  That of the vocal folds &larynx below the level of the vocal folds,is supplied by the recurrent laryngeal n. The motor nerve supply: To the intrinsic muscles of the larynx is the recurrent laryngeal (R.L.N) nerve, except for the cricothyroid m. by the external laryngeal nerve of the superior laryngeal branch of vagus. Dr: the Azza Zaki

Section of the external laryngeal nerve: Produces weakness (hoarseness) of the voice because the vocal fold cannot be tensed due to paralysis of the cricothyroid m. inability to produce higher frequencies . Unilateral complete section of the R.L.N: results in the vocal fold on the affected side assuming the position midway between abduction & adduction. Speech is not greatly affected because the other fold Compensates & moves toward Dr: Azza Zaki the affected vocal fold.

Bilateral complete section of the R.L.N: Results in both vocal folds assuming the position midway between abduction & adduction (cadaveric position). Breathing is impaired & speech is lost (aphonia). Unilateral partial section of the R.L.N: Results in a greater degree of paralysis of the abductor muscles than of the adductor muscles due to the nerve fibers to the abductor muscles are traveling in a more exposed position. The affected vocal fold assumes the adducted midline position. Bilateral partial section of the R.L.N: results in bilateral paralysis of the abductor muscles &adduction of vocal folds Acute breathlessness (dyspnea)& stridor & Dr: Azza Zaki Dr: Azza Zaki

The m.m of the larynx is loosely attached to the underlying structures by submucous C.T. in the region of the vocal folds, however the m.m is firmly attached to the vocal ligaments. In case of edema of the larynx . The accumulation of tissue fluid causes the m.m above the rima glottidis to swell & encroach on the airway. in severe cases, Dr: Azza Zaki cricothyroidotomy or tracheostomy may

The interior of the larynx can be inspected directly using the laryngoscope. The valeculla, the piriform fossae, the epiglottis, & the aryepiglottic folds are clearly seen. the 2 elevations produced by the corniculate & cuneiform cartilages can be recognized. within the larynx, the vestibular folds (are fixed, widely separated& reddish) & the vocal folds (move with respiration& are white in color) & inside of trachea can be seen. With quiet breathing , the rima glottidis is triangular , with the apex in front. With deep breathing, the rima Glottidis assumes a diamond shape Dr: arytenoid. Azza Zaki due to rotation of the

Dr: Azza Zaki

References 



  

Clinical anatomy by systems. Snell 2007 Clinically oriented anatomy 5th ed Moore Gray’s anatomy for students. Drake Netter atlas Grant’s atlas of anatomy Dr: Azza Zaki