Anatomy of the larynx by arijit

STRUCTURE OF THE LARYNX• Larynx is our VOICE BOX.

• The Larynx extends from Laryngeal inlet above to the lower border of Cricoid cartilage below.

• Functions of Larynx : 1. Protective function2. Voice production

INFANTILE LARYNX Lumen narrower

More funnel-shaped

Narrowest part is the junction of the sub-glottic larynx with the trachea

Cartilages are much softer and hence collapses more easily on forced inspiration.

Placed more high up.

EMBRYOLOGY Primitive larynx: cranial end of

laryngo-tracheal groove

Laryngeal mucosa: endoderm

Laryngeal cartilages & muscles: mesenchyme

EMBRYOLOGY Epiglottis- hypobranchial eminence

Upper part of thyroid cartilage-4th arch

Lower part of thyroid cartilage, cricoid, corniculate, cuneiform, intrinsic muscles-6th arch

Upper part of body& lesser cornu of hyoid-2nd arch

Lower part of body & greater cornu of hyoid-3rd arch

STRUCTURE OF LARYNX Laryngeal framework is

formed by –

1. Cartilages2. Membranes & ligaments3. Muscles of larynx

LARYNGEAL CARTILAGES Paired

Arytenoid cartilage Corniculate cartilage Cuneiform cartilage

Unpaired: Thyroid cartilage Cricoid cartilage Epiglottis

THYROID CARTILAGE Hyaline cartilage

Largest.

Encloses the larynx anteriorly and laterally

Two alae

Ossification.

THYROID CARTILAGE Internal surface gives attachments to – Thyro-epiglottic ligament, paired vocal and vestibular ligaments and Vocalis, Thyro-arytenoid and Thyro-epiglotticus muscles.

CRICOID CARTILAGE Hyaline cartilage

StrongestShape: Signet ringLamina – flat portion

Only complete annular support of the larynx

Articulates with Inferior cornu of the thyroid cartilage

EPIGLOTTIS Fibro elastic cartilage

Leaf-shaped structure

Petiole – small narrow stalk like portion of the epiglottis attached to the thyroid cartilage.

Contains a tubercle on its posterior surface.

EPIGLOTTIS (contd.)

ARYTENOID CARTILAGES Mostly hyaline cartilage Smaller in size Responsible for opening and closing

of the larynx Shape: pyramidal

ARYTENOID CARTILAGES Anterior Vocal process -

receives the attachment of the mobile end of each VC

Lateral Muscular process

Articulation Cricoarytenoid

joint

CORNICULATE CARTILAGES Fibro elastic Cartilages of Santorini Small cartilages above the

arytenoid and in the aryepiglottic folds

CUNEIFORM CARTILAGES

Fibro elastic cartilages

Cartilages of Wrisberg

Elongated pieces of small yellow elastic cartilage in the aryepiglottic folds

TRITICEOUS CARTILAGES Cartilago

triticea

Small elastic cartilage in the lateral thyrohyoid ligament

LARYNGEAL LIGAMENTS Extrinsic Thyrohyoid membrane and

ligaments

Cricothyroid membrane and ligaments

Cricotracheal ligament

Hyo-epiglottic ligament

LARYNGEAL LIGAMENTS Intrinsic

Quadrangular membrane

Conus elasticus (cricovocal membrane)

Median cricothyroid ligament

Vocal Ligament

Thyroepiglottic ligament

EXTRINSIC LIGAMENTSThyrohyoid membraneMedian Thyrohyoid ligament

– thickened median portion

Lateral thyrohyoid ligament

– thickened posterior border

- where cartilago triticea is often found

EXTRINSIC LIGAMENTSThyrohyoid membrane

pierced on each side by:

1. Superior laryngeal vessels

2. Internal branch of superior laryngeal nerve

EXTRINSIC LIGAMENTS

Cricothyroid membrane and ligaments

May be pierced for emergency tracheotomy (cricothyrotomy)

EXTRINSIC LIGAMENTS Crico tracheal Ligament Attaches the cricoid

cartilage to the first attached ring

Hyo-epiglottic Ligament Connects the

anterior surface of epiglottis with Hyoid bone.

HYO-EPIGLOTTIC LIGAMENT

INTRINSIC LIGAMENTS Elastic membrane

Divided into upper and lower parts by the ventricle of the larynx

Forms the fibrous framework of larynx.

INTRINSIC LIGAMENTS Quadrangular membrane Upper part of the elastic

membrane

Boundaries Epiglottis , arytenoid, corniculate cartilage, false cord

Forms part of wall between upper pyriform sinus and laryngeal vestibule

INTRINSIC LIGAMENTS Conus elasticus (cricovocal membrane) Lower part of elastic membrane

Composed mainly of yellow elastic tissue

Median cricothyroid ligament – thickened anteior part

Vocal Ligament – free upper edge

INTRINSIC LIGAMENTS Boundaries

Inferior: superior border of cricoid cartilage

Superoanterior: deep surface of angle thyroid cartilage

Superoposterior: vocal process of arytenoid cartilage

Thyro-epiglottic ligament

INTRINSIC LIGAMENTS OF LARYNX

CAVITY OF THE LARYNX Divided into 3 parts:

Vestibule

Ventricle

Sub glottic space

CAVITY OF THE LARYNX Vestibule –

boundaries: Anterior: posterior

surface of epiglottis

Posterior: interval between arytenoid cartilages

Lateral: inner surface of ary-epiglottic folds and upper surfaces of the false cord

CAVITY OF THE LARYNX• Ventricle • Saccule – conical pouch at anterior part of the ventricle. Lies between Inner surface of thyroid cartilage and false cord. It has numerous mucous glands opening into the surface of its lining mucosa for lubricating the vocal cords.

• SUBGLOTTIC SPACE

RIMA GLOTTIDIS Space between free margin of true cords

Two portions – Anterior or

Inter-membranous (3/5 th)

Posterior or Inter-cartilagenous (2/5 th)

RIMA GLOTTIDIS

CAVITY OF THE LARYNXFalse Cords (ventricular bands)

Anteriorly: angle of the thyroid cartilage

Posteriorly: bodies of the arytenoid cartilage

CAVITY OF THE LARYNXTrue cordsVoice productionProtection of lower respiratory tractAnteriorly,: angle of thyroid cartilage

Posteriorly : vocal processes of the arytenoid cartilages

Enclose vocal ligament and a major part of the vocalis muscle

VOCAL VOCAL CORDSCORDS The lamina propria

consists of three layers. The most superficial consists of fibrous substance similar to gelatin, and is loosely attached to the underlying vocal ligament

The intermediate layer

consists of elastic fibres, and the deep layer is formed of collagen fibres; these two layers collectively form the vocal ligament

Fibres of the vocalis muscle form the fifth layer of the vocal folds

POTENTIAL TISSUE SPACES REINKE`S SPACE:-

Between superficial layer of lamina propria and mucosa of vocal cords.

PARAGLOTTIC SPACE:- between the membranes of the larynx and the thyroid cartilage

PRE-EPIGLOTTIC SPACE Pre-epiglottic space of boyer:- • Between hyoid & thyrohyoid

membrane anteriorly and infrahyoid epiglottis Posteriorly.

• Fat filled

• Sparse blood supply, so relatively radio-resistant

• Invasion of this space- Stage T3 in TNM classification.

JOINTS OF LARYNX Cricothyroid joint

1. Synovial joint

2. Formation -inferior horn of thyroid cartilage and a facet in the cricoid

Two types movements:

RotationGliding

JOINTS OF LARYNX Crico-arytenoid jt.-

1. Synovial joint

2. Formation-base of arytenoid and facet on the upper border of cricoid lamina

3. Types of movement- A) Rotatory along

vertical axis, causing abduction & adduction of vc

b) gliding

MUSCLES OF LARYNX Extrinsic

Intrinsic

EXTRINSIC MUSCLES OF LARYNX Attach larynx to surrounding

structures.

DIRECT ELEVATORS: Stylopharyngeus, Palatopharyngeus, Salpingopharyngeus, Thyrohyoid

INDIRECT ELEVATORS : Mylohyoid, Geniohyoid , Stylohyoid & Digastric

DEPRESSORS: Sternothyroid, Sternohyoid,Omohyoid

Depressor Depressor musclesmuscles

OriginOrigin InsertionInsertion ActionAction

Sternohyoid Sternohyoid manubrium manubrium of sternum of sternum and medial and medial end of end of clavicleclavicle

oblique line of oblique line of the thyroid the thyroid cartilagecartilage

depresses/depresses/stabilizes the stabilizes the hyoid bonehyoid bone

Omohyoid Omohyoid superior superior border of border of scapula near scapula near the the suprascapulsuprascapular notchar notch

inferior inferior border of border of hyoid bonehyoid bone

depresses, depresses, retracts and retracts and steadies the steadies the hyoid during hyoid during swallowing swallowing and speakingand speaking

SternothyroiSternothyroid Muscle d Muscle

Superior Superior attachment: attachment: oblique line oblique line of thyroid of thyroid cartilage.cartilage.

Inferior Inferior attachment: attachment: posterior posterior surface of surface of manubrium of manubrium of sternum.sternum.

It depresses It depresses the hyoid the hyoid bone and bone and larynx larynx

Primary Primary Elevator Elevator musclesmuscles

OriginOrigin InsertionInsertion ActionAction

StylopharyngeStylopharyngeusus

styloid styloid process process of of temporal temporal bonebone

posterior and posterior and superior superior borders of borders of thyroid thyroid cartilage with cartilage with palatopharyngpalatopharyngeus muscleeus muscle

elevates the elevates the pharynx and pharynx and larynx and larynx and expands the sides expands the sides of the pharynxof the pharynx

SalpingopharySalpingopharyngeus ngeus

cartilagincartilaginous part ous part of the of the auditory auditory tubetube

blends with blends with palatopharyngpalatopharyngeus muscleeus muscle

elevates the elevates the pharynx and pharynx and larynx and opens larynx and opens the orifice of the the orifice of the auditory tube auditory tube during swallowingduring swallowing

PalatopharyngPalatopharyngeuseus

hard hard palate palate and and palatine palatine aponeuroaponeurosissis

lateral wall of lateral wall of pharynxpharynx

tenses the soft tenses the soft palate and pulls palate and pulls the walls of the the walls of the pharynx pharynx superiorly, superiorly, anteriorly and anteriorly and medially during medially during swallowingswallowing

SecondarSecondary y

Elevator Elevator musclesmuscles

OriginOrigin InsertionInsertion ActionAction

GeniohyoGeniohyoid id

inferior inferior mental spine mental spine of mandibleof mandible

body of hyoid body of hyoid bonebone

pulls the hyoid bone pulls the hyoid bone anterosuperiorly, and anterosuperiorly, and shortens the floor of the shortens the floor of the mouth and widens the mouth and widens the pharynxpharynx

DigastricDigastrics s

anterior anterior belly-belly-digastric digastric fossa of fossa of mandible, mandible, posterior posterior belly-mastoid belly-mastoid notch of notch of temporal temporal bonebone

intermediate intermediate tendon to tendon to body and body and greater horn greater horn of hyoid boneof hyoid bone

depresses the mandible depresses the mandible and raises the hyoid and raises the hyoid bone. Also, it steadies bone. Also, it steadies the hyoid bone during the hyoid bone during swallowing and swallowing and speakingspeaking

MylohyoiMylohyoid d

mylohyoid mylohyoid line of line of mandiblemandible

raphe and raphe and body of hyoid body of hyoid bonebone

elevates the hyoid elevates the hyoid bone, floor of the mouth bone, floor of the mouth and the tongue during and the tongue during swallowing and swallowing and speakingspeaking

StylohyoiStylohyoid d

styloid styloid process of process of the temporal the temporal bonebone

body of hyoid body of hyoid bonebone

elevates and retracts elevates and retracts the hyoid bone, thereby the hyoid bone, thereby elongating the floor of elongating the floor of the mouththe mouth

EXTRINSIC MUSCLES OF LARYNX

EXTRINSIC MUSCLES OF LARYNX (contd.)

INTRINSIC MUSCLES OF LARYNX Interarytenoid muscle Transverse Oblique

Post. Cricoarytenoid m.

Lateral cricoarytenoid m.

Thyroarytenoid m.

Cricothyroid m.

Muscles Controlling Movements of the Vocal CordsIntrinsic Intrinsic

MusclesMusclesOriginOrigin InsertionInsertion ActionAction

Posterior cricoarytenoid

posterior posterior surface of surface of the lamina the lamina of the of the cricoid cricoid cartilagecartilage

muscular muscular process of process of the arytenoid the arytenoid cartilagecartilage

Abduct vocal Abduct vocal cordcord

Interarytenoid m., transverse

posterior posterior surface of surface of the the arytenoid arytenoid cartilagecartilage

posterior posterior surface of the surface of the contralateral contralateral arytenoid arytenoid cartilagecartilage

Closes Closes posterior part posterior part of rima of rima glottidis by glottidis by approximatinapproximating arytenoid g arytenoid cartilagescartilages

Muscles Controlling Movements Of The Vocal Cords Intrinsic

Muscles Origin Insertion Action

Lateral Crico-arytenoid

Lateral part of upper border of arch of Cricoid

Muscular process of Arytenoid

Adductor of the vocal cord.

Crico-thyroid Lower border and lateral surface of Cricoid

Inferior cornu and lower border of Thyroid cartilage.

Tensor of Vocal cords

MUSCLES CONTROLLING THE LARYNGEAL INLETIntrinsic Intrinsic MusclesMuscles

OriginOrigin InsertionInsertion ActionAction

Interarytenoid m., oblique

muscular muscular process of process of the the arytenoid arytenoid cartilagecartilage

posterior posterior surface of the surface of the contralateral contralateral arytenoid arytenoid cartilage, near cartilage, near its apexits apex

draws draws arytenoid arytenoid cartilages cartilages together, together, adducting the adducting the vocal folds vocal folds (closure of (closure of glottis)glottis)

Thyroepiglottic

inner surface inner surface of the of the thyroid thyroid cartilage cartilage near the near the laryngeal laryngeal prominenceprominence

lateral surface lateral surface of the of the epiglottic epiglottic cartilagecartilage

draws the draws the epiglottic epiglottic cartilage cartilage downwarddownward

MUCOUS MEMBRANE Stratified squamous epith.: over vocal cords

and upper part of vestibule of larynx

Ciliated columnar epith.: remainder of the cavity

Mucous glands: Ventricles and sacculi Posterior surface of epiglottis Margins of aryepiglottic folds

Reinke’s layer of connective tissue: No glands and no lymph vessels

NERVE SUPPLY Inferior (recurrent) laryngeal n.

Motor – all intrinsic laryngeal muscles of SAME side (except cricothyroid) and interarytenoid muscle of BOTH sides

Sensory – areas below the glottis

NERVE SUPPLY Supplied by Vagus nerve:

Superior laryngeal n.Internal branch (sensory) – areas above the glottis

External branch (motor and sensory)

Motor – Cricothyroid muscle Sensory – Anterior infraglottic larynx at level of cricothyroid membrane

ARTERIAL SUPPLY Area above vocal cords Superior

laryngeal artery

Area below vocal cords Inferior

laryngeal artery

VENOUS DRAINAGE Upper Larynx

Superior laryngeal vein

Lower Larynx Inferior

laryngeal vein

LYMPHATIC DRAINAGE Supraglottis:-

upper deep cervical nodes

Glottis:- sparse, except for a

small lymph node in the cricothyroid membrane delphian node

Subglottis:- lower deep cervical

and mediastinal lymph nodes via prelaryngeal and paratracheal nodes

INDIRECT LARYNGOSCOPY