ANATOMY & PHYSIOLOGY OF LARYNX Done by : Deem Hatim Al-Fandi Alsafa Abdulaziz Al-Kulaib Norah Abdulaziz Al-Musallam

INTRODUCTION : The larynx lies in front of the hypopharynx opposite to the 3rd till 6th cervical vertebrae. It moves vertically and in anteroposterior direction during swallowing and phonation. It can also be passively moved from side to side producing a characteristic grating sensation called laryngeal crepitus

Larynx has three unpaired & three paired cartilages. 1. LARYNGEAL CARTILAGES Larynx has three unpaired & three paired cartilages.

Paired : Unpaired: Cartilages of Larynx : Arytenoid Corniculate cunieform Unpaired: Thyroid Cricoid Epiglottic

Unpaired Cartilages : Thyroid: It is the largest of all. Its two alae meet anteriorly forming an angle of 90° in males and 120° in females. Vocal cord are attached to the middle of thyroid angle ,Most of laryngeal foreign bodies are arrested above the vocal cords. Cricoid: It is the only cartilage forming a complete ring. Epiglottis: it is a leaf- like , yellow elastic ,forming anterolateral wall of laryngeal inlet

paired Cartilages : Arytenoid cartilages: Each arytenoid cartilage is pyramidal in shape. It has base which articulate with cricoid cartilage Corniculate cartilages ( of Santorini) they are paired , each articulate with apex of arytenoid cartilage Cuneiform cartilages (of Wrisberg). They are rod shaped.

Thyroid, cricoid and most of the arytenoid cartilages are hyaline cartilages whereas epiglottis, corniculate, cuneiform and tip of arytenoid near the corniculate cartilage are fibroelasticin nature .

2. LARYNGEAL MUSCLES They are of two types: intrinsic, which attach laryngeal cartilages to each other & extrinsic, which attach larynx to the surrounding structures.

Abductors: Posterior cricoarytenoid Intrinsic muscles: They may act on vocal cords or laryngeal inlet. Acting on vocal cords: Abductors: Posterior cricoarytenoid Adductors: Lateral cricoarytenoid – Interarytenoid -Thyroarytenoid Tensors: Cricothyroid -Vocalis Acting on laryngeal inlet: Openers of laryngeal inlet: Thyroepiglottic (the internal part of thyroarytenoid) • Closers of laryngeal inlet: Interarytenoid (oblique part).

3. LARYNGEAL MUCOUS MEMBRANE Epithelium of the mucous membrane is ciliated columnar type except over the vocal cords and upper part of the vestibule where it is striated squamous type. There are NO mucous glands in the vocal folds. .

4. LARYNGEAL NERVE SUPPLY Motor & sensory

NERVE SUPPLY: Motor: All the muscles which moves the vocal cord are supplied by: the recurrent laryngeal nerve except the cricothyroid muscle. (innervated by the superior laryngeal nerve). Sensory: Above the vocal cords, larynx is supplied by superior laryngeal nerve. Below the vocal cords by recurrent laryngeal nerve.

The larynx of an infant differs considerably from that of an adult: PAEDIATRIC LARYNX The larynx of an infant differs considerably from that of an adult: Position Laryngeal cartilage Thyroid cartilage Size and diameter Submucosal tissue

POSITION: Infant’s larynx is positioned higher at the level of C3 or C4 at rest, and reaches C1 or C2 during swallowing. With growth of the neck, larynx gradually descends to adult level; the vocal cords lying opposite C5. This high position allows the epiglottis to meet soft palate and make a nasopharyngeal channel for nasal breathing during suckling.

LARYNGEAL & THYROID CARTILAGE Laryngeal cartilages are soft and collapse easily. Epiglottis is omega shaped . Thyroid cartilage is flat.

SIZE AND DIAMETER Small and conical Diameter of cricoid cartilage is smaller than the size of glottis. Making the subglottis the narrowest part. SUBMUCOSAL TISSUE Loose and easily undergo edematous change with trauma or inflammation leading to obstruction.

The larynx performs the following important functions: PHYSIOLOGY O F LARYNX The larynx performs the following important functions: Protection of lower airways , Phonation, Respiration & Fixation of the chest.

1. Protection of lower airways : The larynx protects the Lower passages in three different ways: Sphincter closure of laryngeal opening. Cessation of respiration Cough reflex.

2. Phonation Larynx is like a wind instrument ,Voice is produced by the Following mechanism (Aerodynamic myoelastic theory of voice Production) Vocal cords are kept adducted. Infraglottic air pressure is generated by the exhaled air From the lungs due to contraction of thoracic and Abdominal muscles. The air force open the cords and is released as small puffs which vibrate the vocal cords and produce sound is amplified by mouth and chest.

3. Respiration Larynx regulates flow of air in to the lungs. vocal cords abduct during inspiration and adduct during expiration.

Reference:

Thanks! Any questions?