Larynx 1

The Larynx •

The Larynx • The larynx is a specialized

organ that : • 1.provides an air passage. • 2.provides a protective sphincter at the inlet of the lower respiratory passages. • 3.is responsible for voice production.

• Situation: • -in the anterior midline of the neck • -above it opens into the laryngeal part of the pharynx & below it is continuous with the trachea. • Size :length • Male:44mm Female:36mm

Constitution of the larynx :

• Made up of skeletal framework of cartilages. • Are connected by joints, ligaments & membranes.

• The skeleton or Cartilages of Larynx : • • • • •

Contains 9 cartilages, of which 3 are unpaired & 3 paired. Unpaired cartilages : 1.Thyroid 2.Cricoid 3.Epiglotic

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Paired cartilages : 1. Arytenoid 2.Corniculate 3.Cuneiform.

Thyroid Cartilage : • Consists of 2 laminae of quadrilateral shaped

• • • •

hyaline cartilage meeting in the prominent V angle of the Adam’s apple. -median projection called the laryngeal prominence. -thyroid notch -the superior & inferior cornua or horns. -oblique line.

Cricoid Cartilage • -hyaline type of cartilage, shaped like a ring. • -encircles the larynx below the thyroid cartilage and is thicker &

stronger than the thyroid cartilage. • -narrow anterior arch & broad posterior lamina. • -articulates superiorly with the arytenoid cartilages & at the sides with the inferior cornua of the thyroid cartilage.

Epiglotic Cartilage/Epiglottis : • • • •

-is a leaf shaped cartilage placed in the anterior wall of the upper part of the larynx. -upper end is broad & free ; lower end or stalk is pointed. -the aryepiglotic folds

Arytenoid Cartilage : • -small, 2 in number, • • • •

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pyramidal. -lies in the upper border of the lamina of the cricoid cartilage. -the apex of the arytenoid cartilage is curved posteromedially. -the base is concave. -it is prolonged anteriorly to form the vocal process ; & laterally to form the muscular process. -anterolateral, medial & posterior surfaces.

Corniculate Cartilages : • -2 small conical nodules which articulate with the apex of the • arytenoid cartilages.

Cuneiform Cartilages : • -two small rod-shaped pieces of cartilage placed in the aryepiglotic folds.

Histology of Laryngeal Cartilages : • The thyroid & cricoid cartilages,& the basal parts of the arytenoid •

cartilages are made up of hyaline cartilage. Epiglottis, corniculate, cuneiform & processes of the arytenoid are made of elastic cartilage.

• Laryngeal joints : • -the cricothyroid joint; • -the cricoarytenoid joint.

Membranes & ligaments of the larynx: • Extrinsic : • 1.The thyrohoid membrane • connects the thyroid cartilage • to the hyoid bone. • 2.The hyoepiglottic ligament • 3.The cricotracheal ligament.

• Intrinsic :

• The intrinsic ligaments are • • • •

part of a broad sheet of fibroelastic tissue,known as the fibroelastic membrane of the larynx. The quadrate membrane. The conus elasticus.

Cavity of Larynx : • The cavity of the larynx • •

extends from the inlet of the larynx to the lower border of the cricoid cartilage. The inlet of the larynx is placed obliquely. Boundaries of the inlet :

• Within the cavity of the • • • • •

larynx, there are 2 folds of mucous membrane on each side. -The upper fold is the vestibular fold & the lower fold is the vocal fold. -The rima vestibuli -The rima glottidis The vestibular & vocal folds divide the cavity of the larynx into 3 parts :1.the vestibule 2.the sinus or ventricle 3.the infraglottis.

Muscles of the Larynx: • • • •

The muscles can be divided into extrinsic & intrinsic groups : 1. Extrinsic Muscles : i. The elevators of the larynx ii. The depressors of the larynx. 2. Intrinsic muscles of larynx :

Nerve supply of the intrinsic Muscles :

-the recurrent laryngeal nerve except for the cricothyroid.

• Actions : • The vocal process & muscular processes move in opposite directions. Any muscle which pulls the muscular process medially, pushes the vocal process laterally, resulting in abduction of vocal cords; which is done by posterior cricothyroid.

Movements of Vocal folds : • Movements of vocal folds • • • •

affect the shape & size of the rima glottidis. 1. During quiet breathing : 2. During phonation : 3. During forced inspiration : 4. During whispering :

Artery Supply & Venous Drainage of Larynx : • • • • • •

Up to the vocal folds : - by superior laryngeal artery. - by superior laryngeal vein. Below the vocal folds : - by the inferior laryngeal artery. - by the inferior laryngeal vein.

• Nerve supply of Larynx : • Motor nerves :

All intrinsic muscles by the recurrent laryngeal nerve except for the cricothyroid. • Sensory nerves : • -above the vocal folds : internal laryngeal nerve. -below the vocal folds:recurrent laryngeal nerve.

• Lymphatic Drainage :

- The antero-superior group of deep cervical nodes. • - The postero-inferior group of deep cervical nodes • - The prelaryngeal nodes.

Mechanism of Speech : • It involves the following four • • • •

processes : 1. Expired air from lungs. 2. Vibrators. 3.Resonators. 4.Articulators.

• Clinical Anatomy :

• Abuse of vocal cords : Singer’s • • • • •

nodules or teacher’s nodules. Foreign body in the larynx – severe protective coughing. Glottis is the narrowest of the respiratory passage & foreign bodies are usually lodged here. Laryngitis. Direct Laryngoscopy / Indirect Laryngoscopy. Bilateral recurrent laryngeal nerves damage.

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