LARYNXKhaleel Alyahya, PhD, MEd

www.khaleelalyahya.net

Resources

Essential of Human Anatomy & Physiology

By Elaine Marieb and Suzanne Keller

Atlas of Human Anatomy Gray’s Anatomy KENHUB

By Frank Netter By Richard Drake, Wayne Vogl & Adam Mitchell

www.kenhub.com

The larynx is an organ in the neck of humans that is involved in

breathing, sound production, and trachea protection against food

aspiration.

“

Introduction

▪ Specialized organ at the inlet of air passage.

▪ It is an organ located in the anterior neck.

▪ The structure of the larynx is primarily cartilaginous

and is held together by a series of ligaments and

membranes.

▪ Internally, the laryngeal muscles move components

of the larynx for phonation and breathing.

▪ Superiorly, attached to hyoid bone.

▪ Inferiorly, continues with trachea.

4Khaleel Alyahya, PhD, MEd

Functions

▪ Protective sphincter at the air passage.

▪ Phonation.

▪ Regulates air passage in inspiration and

expiration.

▪ Opens & closes during swallowing, coughing &

sneezing.

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Structure

▪ The larynx is formed by a cartilaginous skeleton, which is

held together by ligaments and membranes.

▪ The laryngeal muscles act to move the components of the

larynx for phonation and breathing.

▪ The internal cavity of the larynx can be divided into three

sections:

• Supraglottis: From the inferior surface of the

epiglottis to the vestibular folds (false vocal cords).

• Glottis: Contains vocal cords and 1cm below them.

• Subglottis: From inferior border of the glottis to the

inferior border of the cricoid cartilage.

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Position & Relation

▪ The larynx is located in the anterior compartment of

the neck, suspended from the hyoid bone and

spanning between C3 and C6.

▪ It is continuous inferiorly with the trachea, and opens

superiorly into the laryngeal part of the pharynx.

▪ It is covered anteriorly by the infrahyoid muscles

(sternohyoid, sternothyroid, thyrohyoid and omohyoid

muscles), and laterally by the lobes of the thyroid

gland. Posteriorly, the oesophagus is located.

▪ The larynx is also closely related to the major blood

vessels of neck, which laterally as they ascend up to

the head.

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Cartilages

▪ Unpaired (Single) Cartilages

• Epiglottis

• Thyroid cartilage

• Cricoid

▪ Paired Cartilages

• Arytenoid

• Corniculate

• Cuneiform

▪ All cartilages are hyaline

• Except the epiglottis

o elastic cartilage

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Framework

▪ The framework of the larynx is made up of cartilages.

▪ These cartilages are connected by joints, membranes &

ligaments.

▪ Moved by muscles.

▪ Lined by mucous membranes.

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Thyroid cartilage

▪ It is the largest of the laryngeal cartilages.

▪ Formed of two laminae, each has superior & inferior horns.

▪ The angle between two laminae is 90 in male & 120 in female.

▪ It has two notches superior & inferior at the meeting of the two

laminae.

▪ Connections:

• Superior: To hyoid bone by thyrohyoid membrane.

• Inferior: To cricoid cartilage by the cricothyroid joint &

cricothyroid membrane

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Cricoid cartilage

▪ Hyaline cartilage.

▪ Ring shaped, having a narrow anterior arch and wide posterior

lamina.

▪ It is the only complete ring of cartilage around the trachea.

▪ Connected superiorly to thyroid cartilage by cricothyroid joint

and cricothyroid membrane.

▪ Inferiorly is connected to the 1st ring of cartilages around the

trachea by the cricotracheal ligament.

▪ The function of the cricoid cartilage is to provide attachments

for muscles, cartilages, and ligaments.

▪ Also it is involved in opening and closing the airway and

in speech production.

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Epiglottis

▪ Leaf-shaped elastic cartilage.

▪ It projects obliquely upwards behind the tongue and the hyoid

bone.

▪ Stands open during breathing allowing air pass into the larynx.

▪ It closes during swallowing to prevent aspiration, forcing the

swallowed liquids or food to the esophagus.

▪ Connected by its stalk to the back of the thyroid cartilage.

▪ Its sides are connected to the arytenoid cartilage by

aryepiglottic fold.

▪ Its upper end is free.

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Arytenoid cartilage

▪ Paired hyaline cartilage.

▪ Shaped like a 3-sided pyramid.

▪ Its base sits on the superior surface of the cricoid lamina.

▪ Apex: directed superiorly, supports the corniculate cartilage.

▪ Muscular process directed laterally, gives attachment to three

muscles:

• Posterior & lateral cricoarytenoid.

• Thyroarytenoid.

▪ Vocal process: directed forward and gives attachment to the

vocal ligament.

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Corniculate cartilages

▪ The corniculate cartilages are minor cartilaginous structures.

▪ They articulate with the apices of the arytenoid cartilages.

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Cuneiform cartilages

▪ The cuneiform cartilages are located within the ary-epiglottic

folds.

▪ They have no direct attachment, but act to strengthen the folds.

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Muscles

▪ Two Major Groups of Muscles:

• Extrinsic Muscles – movement of the whole larynx

o Elevators:

▪ Digastric, stylohyoid, mylohyoid, geniohyoid, stylopharyngeus, salpingopharyngeus & palatopharyngeus.

o Depressors:

▪ Sternothyroid, sternohyoid & omohyoid.

• Intrinsic Muscles - movement within larynx

o Control of laryngeal inlet

o Control of rima glottidis

o Control of length & tension of vocal cords

o All intrinsic muscles lie inside the larynx cricothyroid

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Cricothyroid muscle

▪ Origin: Anterior part of arch of cricoid

▪ Insertion: Inferior border & inferior horn of thyroid

▪ Function: Flexion at cricothyroid joint

▪ Lengthens & tightens the vocal ligament

▪ Nerve supply: External laryngeal nerve of superior laryngeal of vagus.

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Thyroarytenoid muscle

▪ Origin: Front the lower half of the angle of the thyroid cartilage, and

from the middle cricothyroid ligament.

▪ Insertion: Into the base and anterior surface of the arytenoid cartilage.

▪ Function: Draw the arytenoid cartilages forward toward the thyroid to

relax and shorten the vocal folds.

▪ Nerve supply: Recurrent laryngeal nerve.

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Posterior cricoarytenoid muscle

▪ Origin: The posterior surface of the cricoid cartilage.

▪ Insertion: The muscular process of the arytenoid cartilage.

▪ Function: Abducts vocal folds.

▪ Nerve supply: Inferior laryngeal nerve (branch of recurrent laryngeal).

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Lateral cricoarytenoid muscle

▪ Origin: The arch of the cricoid cartilage.

▪ Insertion: The muscular process of the arytenoid cartilage.

▪ Function: Adducts vocal folds.

▪ Nerve supply: Inferior laryngeal nerve (branch of recurrent laryngeal).

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Transverse & Oblique cricoarytenoid muscle

▪ Origin: Spans from one arytenoid cartilage to the opposite arytenoid.

▪ Function: Adducts the arytenoid cartilages.

▪ Nerve supply: Inferior laryngeal nerve (branch of recurrent laryngeal).

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Actions of intrinsic muscles

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Interior of larynx

▪ It is divided into three parts:

• Vestibule: between laryngeal inlet & vestibular fold.

• Ventricle: a depression extending laterally between vestibular & vocal folds.

• Infraglottic cavity lies between the vocal fold & lower border of cricoid cartilage.

▪ It is continuous with the trachea inferiorly.

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Vocal cords

▪ The vocal cords (known also as vocal folds) are located within the

larynx (also colloquially

▪ Known as the voice box at the top of the trachea.

▪ Vocal cords are open during inhalation and come together to close

during swallowing and phonation.

▪ When cords are closed, the vocal folds may vibrate and modulate

the expelled airflow from the lungs to produce speech and singing..

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Innervation

▪ MOTOR

• All muscles of the larynx are supplied by recurrent laryngeal nerveexcept Cricothyroid

o Supplied by external laryngeal branch of superior laryngeal nerve

▪ SENSORY & SECRETOMOTOR

• Above Vocal Cords: internal laryngeal

• Below Vocal Cords: recurrent laryngeal

▪ RECURRENT LARYNGEAL NERVE

▪ A branch of the vagus nerve that supplies all the intrinsic musclesof the larynx, with the exception of the cricothyroid muscles.

▪ The nerves emerge from the vagus nerve at the level of the arch ofaorta, and then travel up the side of the trachea to the larynx.

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Blood supply

▪ ARTERIES

• Superior Laryngeal Artery

o branch of superior thyroid artery

• Inferior Laryngeal Artery

o branch of inferior thyroid artery

▪ VIENS

• The superior and inferior laryngeal veins drain the larynx andshare the same course as the arteries.

• Superior Laryngeal Vein

o drain into the superior thyroid veins, which empty into the internal jugular veins.

• Inferior Laryngeal Vein

o drain into the inferior thyroid veins, which both empty into the left brachiocephalic vein.

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Vocal cords paralysis

▪ The vocal cords are responsible for the production of speech.

▪ Their movement is controlled by the intrinsic muscles of the larynx.

• The majority of which are innervated by the recurrent laryngeal nerve (anexception is the cricothyroid muscle; innervated by the external laryngealnerve).

▪ Due to its long course, the recurrent laryngeal nerve is susceptible to

damage.

▪ If unilateral RLN palsy, one vocal cord is paralysed. The other vocal cord

tends to compensate, and speech is not affected to a great degree,

although the patient may experience hoarseness of voice.

▪ If bilateral RLN palsy, both vocal cords are paralysed in a position between

adduction and abduction. Breathing is impaired, and phonation cannot

occur.

27Khaleel Alyahya, PhD, MEd

QUESTIONS?

alkhaleel@ksu.edu.sa