الرحمن الله بسمالرحيم

Larynx

Objectives Describe anatomical structure of larynx.

Enlist the cartilages of the larynx.

Define inlet of the larynx.

Enlist the extrinsic and intrinsic muscles of the

larynx with their nerve supply and actions.

Larynx

Larynx- The larynx is the organ of phonation (voice production) in

addition to its respiratory function (air way). It is formed of a group of cartilages connected by Muscles, Ligaments and joints.

Site: It lies below the hyoid bone in the midline of the neck at the level of C 4 - 6 vertebrae.

Lateral view Anterior view

StructureThe larynx consists of

four basic components: A cartilaginous skeleton

Membranes and ligaments

Intrinsic and extrinsic muscles

Mucosal lining

Cartilages of the LarynxSingle cartilages Paired cartilages

- Thyroid cartilage. - Arytenoid cartilage.

- Cricoid cartilage. - Corniculate cartilage.

- Epiglottic cartilage. - Cuneiform cartilage.

•All the cartilages, except the epiglottis, are of hyaline type. •Epiglottis is formed of elastic cartilage •The cartilages are:

Connected by joints, membranes & ligaments

Moved by muscles

1. Thyroid cartilageIt consists of two laminae which are fused

anteriorly to form the laryngeal prominence (Adam’s apple) but they are separated posteriorly.

- Superiorly the area between the two laminae is called the superior thyroid notch.

2. Cricoid cartilage- It is signet-ring in shape (it is the only

complete cartilaginous ring in the upper respiratory airway).

- It lies at the level of C. 6.

3. Epiglottis - It is leaf-shaped elastic cartilage which lies

behind the tongue.- It has superior rounded free border and an

inferior tapering end which is attached to the upper part of the thyroid notch.

4.Arytenoid cartilage

It is pyramidal in shape. - The base articulates with the upper facet of the quadrate lamina of the cricoid cartilage.

5. Corniculate cartilage

- It is a small cartilaginous nodule.

- It articulates with the apex of each arytenoid and lies in the aryepiglottic fold.

6. Cuneiform cartilage- It is another small cartilaginous nodule which articulates with the upper surface of the corniculate cartilage and lies in the aryepiglottic fold

Ligaments and Membranes

1. Thyrohyoid membrane:

- It connects the upper border of the thyroid lamina to the body and the greater horns of the hyoid bone.

2. Hyoepiglottic ligament

- It is a small elastic ligament which connects the lower part of the anterior surface of the epiglottis to the hyoid bone.

 3. Thyroepiglottic

ligament- It is a small elastic

ligament which connects the tapering lower end of the epiglottis to the inner

surface of the thyroid cartilage.

• Quadrangular membrane:• Extends between the epiglottis and the arytenoid

cartilages• Its lower free margin forms the vestibular

ligament that lies within the vestibular fold

• Cricothyroid membrane (conus elasticus): • Lower margin

is attached to upper border of cricoid cartilage

• Upper free margin forms vocal ligament

Cavity of larynx

Inlet of the larynxBoundaries: a. Anterior: Upper edge of the

epiglottis.(E) b. On each side:

Aryepiglottic folds.(AEF)

c. Posterior: Mucous fold

between the arytenoids.(A)

Laryngeal Cavity• Extends from laryngeal inlet to

lower border of the cricoid cartilage

• Narrow in the region of the vestibular folds (rima vestibuli)

• Narrowest in the region of the vocal folds (rima glottidis)

• Divided into three parts:A. Supraglottic part, the part

above the vestibular folds, is called the vestibule

B. The part between the vestibular & the vocal folds, is called the ventricle

C. Infraglottic part, the part below the vocal folds

Rima vestibuli

Rima glottidis

B

A

C

Mucous Membrane• The cavity is lined

with ciliated columnar epithelium

• The surface of vocal folds, because of exposure to continuous trauma during phonation, is covered with stratified squamous epithelium

• Contains many mucous glands, more numerous in the saccule (for lubrication of vocal folds)

MusclesDivided into two

groups:• Extrinsic muscles:

divided into two groups• Elevators of the

larynx• Depressors of the

larynx• Intrinsic muscles:

divided into two groups• Muscles

controlling the laryngeal inlet

• Muscles controlling the movements of the vocal cords

Depressors of the Larynx

• The Infrahyoid Muscles Sternohyoid Sternothyroid Omohyoid

Elevators of the Larynx

The Suprahyoid Muscles Digastric Stylohyoid Mylohyoid Geniohyoid

The Longitudinal Muscles of the Pharynx Stylopharyngeus Salpingopharynge

us Palatopharyngeus

Muscles of the Larynx I. Muscles acting on the laryngeal inlet

1. Aryepiglottic muscles :

Action: Closure of the laryngeal inlet.

2. Transverse arytenoid :

Actions: (narrowing the laryngeal inlet) and adducts the vocal cords.

 

= Muscles closing the laryngeal inlet:

3. Oblique arytenoids :

Actions: They narrow the laryngeal inlet) and adducts the vocal cords.

II. Muscles acting on the vocal cordsA: Muscles producing

abduction of the vocal cords:

* Posterior crico-arytenoid:

- It is the ONLY abductor to the vocal cords

Origin: Posterior surface of the lamina of the cricoid cartilage.

Insertion: Muscular process of the arytenoid.

Actions: - Abduction of the vocal

cords.

B. Muscles producing adduction of the vocal cords

1. Lateral crico-arytenoid : Action: It draws the muscular process forwards so it rotates the vocal process inwards and adducts (closes) the vocal cords.

2. Transverse arytenoid

3. Oblique arytenoid

C. Muscles stretching (tensing) the vocal cords 1. Cricothyroid muscle - It lies on the outer surface of

the larynx. Origin: Lateral aspect of the

cricoid arch. Insertion: Into the inferior

horn and lower border of the thyroid lamina.

Actions: It draws the thyroid cartilage downwards and forwards, so it lengthens

and tenses the vocal cords (responsible for the sharp loud voice).

 

D. Muscles relaxing the vocal cords 1. Thyroarytenoid

muscleActions: It shortens

and relaxes the vocal cords, so it changes the pitch of the voice.

2. Vocalis muscle (it is the lower fibers of the thyro-arytenoid muscle)

Action: Relaxation of the vocal cords.

Movements of the Vocal

Cords

Adductio

n

Abduction

Abductor • Posterior

cricoarytenoid

Adductors • Lateral cricoarytenoid• Transverse arytenoid

Nerve supplyA. Motor supply- All intrinsic muscles of the larynx are supplied

by the “recurrent laryngeal nerve” EXCEPT cricothyroid which is supplied by

the external laryngeal nerve.B. Sensory supply- Above the vocal cords ----------------- Internal

laryngeal nerve (from vagus N).- Below the vocal cords ----------------- Recurrent

laryngeal nerve (from vagus N).

Blood supply

Blood supply:A. Arterial supply:1. Above the vocal cords: Superior laryngeal

artery (from the superior thyroid artery). 2. Below the vocal cords: Inferior laryngeal artery

(from the inferior thyroid artery). B. Venous drainage:- It drains its venous blood into the corresponding

superior and inferior thyroid veins respectively.

Thank You