"learning the larynx"

THE

LARYNX

• HOMEPAGE: The larynx has been broken down into sections. Choose the section that you would like to study by clicking on it

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• TEST YOURSELF! Observe the prosection photos throughout the package, and attempt to identify the structures before clicking to reveal the labels

• Most sections have a self-assessment at the end to allow you to check how well you have revised!

INSTRUCTIONS

HAPPY STUDYING!

WELCOME TO THE LARYNX CAL PACKAGE!

LOCATION• Situated in the anterior triangle of the neck

• Extends from the tip of the epiglottis to the inferior border of the cricoid cartilage

• It lies opposite the C3- C6 vertebrae

• It’s bound by the Pretracheal layer of deep cervical fascia

• It lies in the visceral compartment of the neck, along with the pharynx and oesophagus (posteriorly), thyroid, parathyroid glands and thymus and trachea (inferiorly)

• Its location is relatively superficial so many of the laryngeal components are palpable!

With permission from Moore & Agur (3rd ed.)

FUNCTIONS OF THE LARYNX

1. AIRWAY PROTECTION

2. PHONATION

3. RESPIRATION

CLINICAL RELEVANCE

FUNCTIONS OF THE LARYNX1.

AIRWAY PROTECTION2.

PHONATION3.

RESPIRATION

•The most important function!• During swallowing the larynx should be COMPLETELY CLOSED

•The epiglottis is pulled down to cover the laryngeal inlet and divert food into the pharynx during swallowing

•The vocal folds ADDUCT => CLOSURE OF THE RIMA GLOTTIDIS

• This prevents entry of food and fluid through the laryngeal inlet into the lower respiratory tract

CLINICAL RELEVANCE


AIRWAY PROTECTION2.

PHONATION3.

RESPIRATION

•To generate sound the larynx must be PARTIALLY CLOSED

•The vocal folds must be PARTIALLY ADDUCTED

•The RIMA GLOTTIDIS appears SLIT-LIKE

• Force of expired air from lungs causes vibration of vocal folds. . .generating sound!

CLINICAL RELEVANCE


AIRWAY PROTECTION2.

PHONATION3.

RESPIRATION

•To MAINTAIN A PATENT AIRWAY the larynx must be OPEN

• This is achieved by ABDUCTION of the vocal folds

•RIMA GLOTTIDIS appears OPEN/KITE-SHAPED

CLINICAL RELEVANCE

SURFACE ANATOMY

ISTHMUS OF THYROID GLAND

CRICOTHYROID MEMBRANE

1ST TRACHEAL RING

CRICOID CARTILAGETHYROID

CARTILAGE (LARYNGEAL

PROMINENCE)

GREATER HORN OF HYOID BONE

BODY OF HYOID BONE

THYROID GLAND

• BODY OF HYOID BONE

• CRICOTHYROID MEMBRANE• CRICOID CARTILAGE

• LATERAL LOBE OF THYROID GLAND

•1ST TRACHEAL RING• ISTHMUS OF THYROID GLAND• THYROID CARTILAGE

•GREATER HORN OF HYOID BONE

ANTERIOR TRIANGLE


* Have a go at identifying the structures, and then click to reveal the labels *

VERTEBRAL LEVELS OF LANDMARKS

C3

BIFURCATION OF THE COMMON

CAROTID ARTERY

SUPERIOR BORDER OF

THYROID CARTILAGE

C2

HYOID BONE

C5

INFERIOR BORDER OF

THYROID CARTILAGE

C6

BEGINNING OF TRACHEA AND OESOPHAGUS (posteriorly)

CRICOID CARTILAGE

C4

VOCAL FOLDS (attach behind the laryngeal prominence)


THE LARYNGEAL SKELETONA term which refers to the supportive framework of the larynx, which is primarily responsible for maintaining the shape of the organ.

It consists of nine cartilages joined by a series of ligaments and membranes, and reinforced by a selection of muscles

HYOID BONE

TRACHEA

THYROID CARTILAGE

CLINICAL RELEVANCE

HYOID BONE• It’s not actually classified as part of the larynx but is still very important!

• A horse-shoe shaped bone

• It’s suspended in the neck by ligaments and muscles, and doesn’t articulate with any other bones or cartilages

MAJOR HORNS

MINOR HORNSBODY OF HYOID

BONEANTERIOR

VIEW

CARTILAGES OF THE LARYNX

Divided into 2 groups

POSTERIOR VIEW

EPIGLOTTIC

THYROIDARYTENOIDS

CRICOID

SINGLE

•THYROID CARTILAGE

•CRICOID CARTILAGE

• EPIGLOTTIC CARTILAGE

PAIRED

•ARYTENOID CARTILAGES

•CORNICULATE CARTILAGES

•CUNEIFORM CARTILAGES

THYROID CARTILAGE• The largest cartilage in the laryngeal skeleton

OBLIQUE LINE

•Site for attachment for: •Thyrohyoid muscle, •Sternohyoid• Inferior constrictor of the pharynx.

LARYNGEAL PROMINENCE

• Formed by fusion of the laminae in the midline• Angle of approx.•90O in males•120O in females.• The vocal ligament attaches just behind this

SUPERIOR HORN

THYROID LAMINAE

• 2 flat quadrilateral plates

INFERIOR HORNArticulates with the cricoid cartilage at the CRICOTHYROID JOINTS

Image adapted from Gray’s Anatomy for students

PROSECTION PICHYOID BONE

THYROHYOID MEMBRANE

CRICOID CARTILAGE

CRICOTHYROID MEMBRANE

INFERIOR HORN

ATTACHMENT OF VOCAL FOLDS


INFERIOR THYROID NOTCH

ANTERIOR VIEW

POSTERIOR VIEW

THYROID LAMINA

SUPERIOR THYROID NOTCH

SUPERIOR HORN

• INFERIOR THYROID NOTCH

• THYROID LAMINA

• ATTACHMENT OF VOCAL

FOLDS• INFERIOR

HORN• SUPERIOR

THYROID NOTCH

• LARYNGEAL PROMINENCE• SUPERIOR

HORN


CRICOID CARTILAGE

ARCH (anterior)

The only cartilage to form a complete ring around the airway• Is both stronger and thicker than the thyroid cartilage•Signet-ring shaped

LAMINA (posterior)

•“signet” aspect is wider•the arytenoid cartilages sit on top

FACETS (lateral aspects)

Articulate with the Inferior horns of the thyroid cartilage

The lobes of thyroid gland also attaches to it’s lateral surface1st TRACHEAL RING

CRICOTRACHEAL MEMBRANE

POSTEROLATERAL VIEW


PROSECTION PIC

ANTEROLATERAL VIEW POSTERIOR VIEW

VOCAL PROCESSES

(attachment of vocal ligaments)

ARCH (anterior) LAMINA (posterior)

ARYTENOID CARTILAGES

• CRICOID ARCH• CRICOID LAMINA• VOCAL PROCESS• ARYTENOID


EPIGLOTTIC CARTILAGE• A leaf-shaped elastic cartilage located posterior to the hyoid bone and the root of the tongue • Forms the superior margin of the laryngeal inletThe broad SUPERIOR

ASPECT of the cartilage is free

EPIGLOTTIC CARTILAGEattaches to: Thyroid cartilage via

THYROEPIGLOTTIC LIGAMENT

Hyoid bone via HYOEPIGLOTTIC LIGAMENT

SAGITTAL SECTIONImage adapted from Clinical Voice Disorders 3rd ed.

Arytenoid cartilages (posteriorly) via QUADRANGULAR MEMBRANE

CRICOARYTENOID JOINTS:-

•These allow tilting,sliding and rotation of the arytenoid cartilages anteriorly, posteriorly, laterally and medially•Each movement causes a change in the length, tension and position of the vocal folds and therefore has an impact on laryngeal function

SAGITTAL SECTION

ARYTENOID CARTILAGES• These triangular-based pyramidal structures have a posterior location, and sit on the lamina of the cricoid cartilage

• Don’t be fooled by their small size- they’re very important structures!

* EACH ARYTENOID HAS 4 SURFACES *

BASE

Articulates with the cricoid lamina at the cricoarytenoid joints

Image adapted from Clinical Voice Disorders 3rd ed.

ARYTENOID CARTILAGES

MEDIAL SURFACE

Smooth and covered with mucous membrane

ANTEROLATERAL SURFACE

Site for attachment of

•Vestibular ligament

•Thyroarytenoid and vocalis muscles

POSTERIOR SURFACE

attachment of • Transverse arytenoid• Oblique arytenoid muscles

SUPERIOR VIEWTHYROID CARTILAGE

VOCAL LIGAMENT

CRICOID CARTILAGE

ARYTENOID CARTILAGES• Each Arytenoid cartilage has 3 KEY PROJECTIONS

VOCAL PROCESS

Site for posterior attachment of vocal ligament

MUSCULAR PROCESS

Site of attachment of• Lateral cricoarytenoid • Posterior cricoarytenoid muscles

APEX•Articulates with the corniculate cartilages above• Attaches to the aryepiglottic fold.

Image adapted from Clinical Voice Disorders 3rd ed.

SAGITTAL SECTION

PROSECTION PIC

VOCAL PROCESSES

APEXMUSCULAR PROCESSES

Knowledge of these projections is key to understanding the actions of the intrinsic muscles involved in movement of the vocal folds

CRICOID CARTILAGE

SUPERIOR VIEW

LATERAL VIEW

POSTERIOR

ANTERIOR


CORNICULATES & CUNEIFORMS

• These are the smallest cartilages and are of no major functional importance.

CORNICULATES

Lie on the apices of the arytenoid cartilages

CUNEIFORMS

Are suspended in the mucous membrane of the aryepiglottic folds

ARY-EPIGLOTTIC FOLD

VOCAL LIGAMENT

ARYEPIGLOTTIC LIGAMENT (superior)

VESTIBULAR LIGAMENT (inferior)

THYROHYOID MEMBRANE• It attaches the superior border of the thyroid cartilage with the hyoid bone

MEDIAN THYROHYOID

LIGAMENTThe thickened

central portion of the membrane

Penetrated by• superior laryngeal

artery • internal laryngeal

nerve

LATERAL THYROHYOID

LIGAMENTThe lateral aspect of the membrane

Back to membranes


CRICOTHYROID MEMBRANE• It attaches. . .

ANTERIORLY along the inferior border of the thyroid cartilage

INFERIORLY along the superior border of the cricoid arch

POSTERIORLY to the vocal processes of the arytenoid cartilages

It’s thickened FREE UPPER MARGIN forms the VOCAL LIGAMENT; the skeleton of the vocal fold. It runs from the junction behind the laryngeal prominence to the vocal processes. The horizontal space between the 2 vocal folds = RIMA GLOTTIDIS


CLINICAL RELEVANCE

Back to membran

es

QUADRANGULAR MEMBRANEAttaches the sides of the epiglottis lateral aspects of the arytenoid cartilages

It’s Free INFERIOR MARGINS

VESTIBULAR LIGAMENTS

VESTIBULAR FOLDS

It’s Free SUPERIOR MARGINS

ARYEPIGLOTTIC LIGAMENTS

ARYEPIGLOTTIC FOLDS


Back to membra

nes

TEST YOURSELF: CARTILAGES & MEMBRANES1. The cuneiform cartilages articulate with the corniculate cartilages

2. Only sliding movements of the arytenoid cartilages are possible at the cricoarytenoid joints.

3. In emergencies when there is obstruction of the larynx above the vocal folds, the thyrohyoid membrane can be punctured to allow air into the airways

4. The lateral lobes of the thyroid gland lie on the cricoid cartilage

5. The tip of the epiglottis extends above the hyoid bone

FALSE they actually are isolated, and don’t make contact with any cartilages or bony structures, instead they are suspended in the ary-epiglottic fold.

FALSETRUE

FALSETRUE

FALSETRUE

TRUE FALSE

TRUE FALSEOn to

Relevant Vessels

RELEVANT

VESSELS

ARTERIAL SUPPLY

SUPERIOR LARYNGEAL ARTERY

INFERIOR LARYNGEAL ARTERY VENOUS DRAINAGE

INFERIOR LARYNGEAL VEIN

SUPERIOR LARYNGEAL VEIN

LYMPHATIC DRAINAGE INFERIOR DEEP CERVICAL

NODES

SUPERIOR DEEP CERVICAL NODES

ARTERIAL SUPPLY

ARCH OF AORTA

Ascends in the groove between the trachea and the oesophagus with the Recurrent Laryngeal nerve and then passes deep to the inferior constrictor of the pharynx


VENOUS DRAINAGE

The venous drainage of the larynx is through the SUPERIOR and INFERIOR LARYNGEAL VEINS which accompany their respective arteries

They ultimately drain into the the left and right INTERNAL JUGULAR VEIN BRACHIOCEPHALIC VEINS

LYMPHATIC DRAINAGE

VOCAL FOLDS

RIMA GLOTTIDIS= horizontal space between the two vocal cordsTHE GLOTTIS = the vocal apparatus of the larynx comprised by the VOCAL CORDS and RIMA GLOTTIDIS LYMPH VESSELS surrounding the vocal folds are sparse. As a result patients with CARCINOMA OF THE GLOTTIS often have a good prognosis as there is a reduced chance of metastasis through the lymphatics, and hoarseness is an early and easily identifiable symptom.

The part of the larynx BELOW the VOCAL FOLDS drains into the INFERIOR DEEP CERVICAL NODES

The part of the larynx ABOVE the VOCAL FOLDS drains into the SUPERIOR DEEP CERVICAL NODES

On to INNERVATION

INNERVATIONMEDULLA

JUGULAR FORAMEN

VAGUS (CNX)

INFERIOR VAGAL

GANGLION

SUPERIOR VAGAL

GANGLION

COMMON CAROTID ARTERY

INTERNAL JUGULAR VEIN

SUPERIOR LARYNGEAL

NERVE

INTERNAL LARYNGEAL NERVE

Provides SENSORY fibres to the mucosa ABOVE the level of the VOCAL FOLDS

Provides MOTOR fibres to the cricothyroid muscle

EXTERNAL LARYNGEAL NERVE

The nerve supply to the larynx comes from the superior laryngeal nerve and the recurrent laryngeal nerve, both are branches of the Vagus (CNX)

RECURRENT LARYNGEAL NERVE

RECURRENT LARYNGEAL NERVES (RLNs)

• After looping, both RLNs ascend between the trachea and oesophagus

• They pierce the inferior constrictor of the pharynx to enter the larynx

• They continue as the inferior laryngeal nerves to provide the MOTOR SUPPLY to all the intrinsic muscles of the larynx except the Cricothyroid muscles

•Provide SENSORY FIBRES to mucosa BELOW the VOCAL FOLDS.

Loops under the Arch of the Aorta, posterior to the Ligamentum Arteriosum

LEFT RLN RIGHT RLNLoops under the Subclavan Artery.

POSTERIOR VIEW ANTERIOR VIEWImage adapted from Gray’s Anatomy for students

RLN DAMAGEThe action of the adductors overpower that of the single abductor muscle (SEMON’S LAW), this causes theaffected vocal cord to adopt a MIDLINE ADDUCTED POSITION

Both vocal cords will be adducted, and the patient will experience STRIDOR; harsh high-pitched wheezing

The innervation to the intrinsic muscles supplied on one side is disrupted, resulting in paralysis of that vocal cord, which then adopts a PARAMEDIAN POSITION midway between adduction and abduction.

Paralysis of both vocal cords results in complete loss of the voice (aphonia). Lack of muscle power to hold open the rima glottidis leads to breathing difficulties

The RLN is at risk of damage during thyroid surgery.The left RLN is more prone to damage as it is longer and has a thoracic course.

RELEVANT VESSELS & INNERVATION QUIZ1. Lesions of the left Recurrent Laryngeal nerve are more common than those of the right.

2. The internal laryngeal nerve is a continuation of the recurrent laryngeal nerves, that contains motor fibres

3. The inferior part of the larynx which lies below the vestibular folds is drained by the inferior deep cervical lymph nodes.

TRUE FALSE

TRUE FALSE

TRUE FALSETRUE The left rln is longer and also has a thoracic course, (unlike the right rln, which stays within the neck) and is therefore more exposed and at greater risk of damage.

FALSE Remember, the VOCAL and not vestibular folds form the barrier between the two “lymphatic regions.”

FALSE Don’t get confused between the internal and inferior laryngeal nerves. Remember internal is a branch of superior laryngeal nerve and enters the larynx superiorly through the thyrohyoid membrane, Inferior is the continuation of the RLN, it approaches the larynx inferiorly as indicated in the name.

RELEVANT VESSELS & INNERVATION QUIZ

4. The superior thyroid artery pierces the thyrohyoid membrane

5. Venous drainage of the larynx is via the superior and inferior laryngeal veins which accompany their respective arteries.

FALSETRUE

TRUE FALSE

On to MUSCLES

•Attach at one end to a laryngeal cartilage and on the other to a bony structure that lies outside the larynx

•Move the entire larynx as a whole unit

•Originate from and insert into structures within the larynx

•Move the individual laryngeal components that they attach to.

•Responsible for movement of the vocal folds

MUSCLES OF THE LARYNX

EXTRINSIC MUSCLESEXTRINSIC INTRINSIC

MYLOHYOID

GENIOHYOID

STYLOHYOID

DIGASTRIC OMOHYOID

STERNOTHYROID

THYROHYOID

STERNOHYOID

SUPRAHYOIDS

MYLOHYOID

GENIOHYOID

ANTERIOR BELLY OF DIGASTRIC


POSTERIOR BELLY OF

DIGASTRIC

STYLOHYOID


STERNOHYOID

INFRAHYOIDS

STERNOTHYROID

THYROHYOID

OMOHYOID


EXTRINSIC MUSCLES: THE BIGGER PICTURE

ANTERIOR BELLY OF DIGASTRIC

POSTERIOR BELLY OF

DIGASTRIC

OMOHYOID

STERNOHYOID

GENIOHYOID

MYLOHYOID

MANDIBLE

HYOID BONE


ANSA CERVICALIS


INTRINSIC MUSCLES•Originate from and insert into structures within the larynx

•Responsible for movement of the vocal folds

•Can be grouped according to this function

HIGHER PITCH SOUND

LOWER PITCH SOUND

WIDER AIRWAY NARROWER AIRWAY

POSTERIOR CRICOARYTENOID

MUSCLES

TRANSVERSE ARYTENOID MUSCLE

LATERAL CRICOARYTENOID MUSCLES

CRICOTHYROID MUSCLES

THYROARTENOID & VOCALIS MUSCLES

OBLIQUE ARYTENOID MUSCLES

CRICOTHYROID MUSCLES

CRICOTHYROIDS ARE UNIQUE BECAUSE THEY ARE THE ONLY INTRINSIC MUSCLES THAT. . . • lie externally on the larynx (therefore seen on anterior view)•Stretch the vocal ligaments• Are innervated by the External Laryngeal nerve

LATERAL VIEW

Attaches the CRICOID ARCH (Anterolateral aspect) INFERIOR BORDER and HORNS of the THYROID CARTILAGE

ACTION: TILTS the thyroid cartilage DOWNWARDS and FORWARDS

This action STRETCHES and TENSES the vocal ligament generates a HIGHER-PITCHED sound


Intrinsic muscles

ACTION: ROTATE the ARYTENOIDS LATERALLY

ABDUCTION OF THE VOCAL FOLDS

OPENS the RIMA GLOTTIDIS

POSTERIOR CRICOARYTENOID MUSCLES* The ONLY ABDUCTORS of the vocal cords. * Bilateral paralysis of the PCAs (due to disruption of their nerve supply) Flaccid closure of the rima glottidis SUFFOCATION!

Attach the ARYTENOIDS (muscular processes)

CRICOID LAMINA(posterior surface)

During deep breathing or forced expiration, the PCAs abduct the vocal folds, rima glottidis is held widely open to allow passage of a greater volume of air through the larynx.


ANTERIOR VIEW

PROSECTION PICPOSTERIOR VIEW

CRICOTHYROID MUSCLE

POSTERIOR CRICOARYTENOID

MUSCLES


LATERAL CRICOARYTENOID MUSCLESAttach the ARYTENOIDS (muscular processes)

ARCH of the CRICOID CARTILAGE

ACTION: ROTATE the ARYTENOIDS MEDIALLY

ADDUCTION OF THE VOCAL FOLDS

This CLOSES the RIMA GLOTTIDIS


Intrinsic muscles

OBLIQUE ARYTENOIDS

ARYEPIGLOTTIC MUSCLES

- Continuations of the Qblique Arytenoids

- Extend from the apices of the arytenoids to the epiglottic cartilage

- They assist in pulling the epiglottis down to cover the laryngeal orifice and divert food into the pharynx during swallowing

Attach the posterior aspect of one ARYTENOID BASE

APEX of the CONTRALATERAL ARYTENOID

ACTION: Cause the ARYTENOIDS to slide MEDIALLY

ADDUCTION OF THE VOCAL FOLDS

CLOSES the POSTERIOR RIMA GLOTTIDIS


Intrinsic muscles

TRANSVERSE ARYTENOID MUSCLE This is the only unpaired muscle associated with the larynx

•It lies deep to the OBLIQUE ARYTENOIDS and has the same action

Attach the lateral aspect of one ARYTENOID

Lateral aspect of the CONTRALATERAL ARYTENOID

•PHONATION *

•Sound production occurs when expired air from lungs passes through the vocal folds and causes them to vibrate, allowing the column of air directly above the folds to act as a resonating chamber

• In order to generate a sound the vocal cords must be closely opposed, causing the rima glottidis to appear slit-like. The 3 adductor muscles achieve this.


Intrinsic muscles

SUPERIOR VIEW

THYROARYTENOID & VOCALISThe Thyroarytenoid muscles form the main body of the vocal folds, and lies lateral to the vocal ligament

Attaches posteriorly to the anterolateral surface of each arytenoid cartilage

anteriorly, just behind the laryngeal prominence.

ACTION: pulls the arytenoid cartilages FORWARD

RELAX THE VOCAL LIGAMENT

generate LOW-PITCHED SOUNDS

VOCALIS- is the medial aspect of the Thyroarytenoid muscle- which is composed of finer fibres.

- It inserts into the vocal fold along its length, and is thought to finely adjust the tension at these points to produce different tones. Functions in fine tuning of the sound produced.


Intrinsic muscles

TEST YOURSELF: MUSCLES 1. The Cricothyroid muscle is classified as an extrinsic muscle

2. The Posterior Cricoarytenoids and the Lateral Cricoarytenoids attach to the same cartilages but have opposing functions

3. Vocalis is the lateral aspect of the Thyroarytenoid muscle that functions in fine tuning of the sound generated

4. The more taut the vocal cords the higher the pitch of the sound generated

FALSE Don’t get confused between extrinsic and external. Remember what extrinsic actually means, and recall the fact that cricothyroid is intrinsic as it both originates from and inserts into laryngeal cartilages

TRUE FALSE

FALSETRUE

TRUE FALSE

FALSETRUE

REMEMBER. . .• All the intrinsic muscles are innervated by the RECURRENT LARYNGEAL NERVE, except for the cricothyroid muscle, which is supplied by the EXTERNAL LARYNGEAL NERVE.

• The Posterior Cricoarytenoid is the only ABDUCTOR of the vocal folds• The Thyroarytenoid forms the main body of the vocal folds and relaxes the vocal ligaments•The Cricothyroid is the only intrinsic muscles that lies externally on the larynx and that tenses the vocal ligaments

5. The Posterior Cricoarytenoid muscles abduct the vocal folds during forced expiration

6. The Sternothyroid muscles lie anterior to the sternohyoid muscles

FALSETRUE

TRUE FALSE

On to INTERIOR COMPARTMENTS

INTERIOR COMPARTMENTS OF THE LARYNX•The laryngeal cavity extends from the laryngeal inlet to the level of the cricoid cartilage

• A coronal section of the larynx, shows the cavity to be hour-glass shaped

• The constriction is formed from two folds; vestibular (superior) and vocal folds (inferior), which divide the cavity into 3 main compartments

FOLDS

•VESTIBULAR FOLDS

•VOCAL FOLDS

COMPARTMENTS•VESTIBULE

•VENTRICLE

•INFRAGLOTTIC CAVITY

INTERIOR COMPARTMENTS OF THE LARYNX

Between the laryngeal inlet and the vestibular folds

VESTIBULE

VESTIBULAR FOLD

VOCAL FOLD

THYROID CARTILAGE

VOCAL LIGAMENT

THYROARYTENOID MUSCLE

CRICOID CARTILAGE

EPIGLOTTIS

HYOID BONE

CORONAL SECTION

VENTRICLEThe lateral recesses between the vestibular and vocal folds

The region below the vocal folds

INFRAGLOTTIC CAVITY

Image adapted from Cunningham's Manual of practical anatomy. Vol. 2, Thorax, head and neck. 6th ed.

PROSECTION PIC

LARYNGEAL INLET

VOCAL FOLDS

VESTIBULAR FOLDS

INFRAGLOTTIC CAVITY

VESTIBULE

LARYNGEAL VENTRICLE

Borders: The epiglottis and the aryepiglottic folds

Also known as the false vocal cords as they aren’t directly involved in phonation. The horizontal space between these 2 folds= RIMA VESTIBULI

LARYNGOSCOPYA superior view of the larynx

Pearly avascular appearance

LARYNGEAL INLET

VESTIBULAR FOLDSVOCAL FOLDS

VALLECULAE

ARYEPIGLOTTIC FOLDS

EPIGLOTTIS

Have a red vascular appearance

CLINICAL RELEVANCE


RIMA GLOTTIDISRIMA VESTIBULI

TEST YOURSELF: INTERIOR COMPARTMENTS1. The cavity that lies between the vestibular and vocal folds is called the

2. The (more inferior) vestibular folds appear pearly and avascular upon laryngoscopy.

3. The vestibular folds form the lateral borders of the laryngeal inlet

4. Identify the numbered structures on the coronal MRI section shown1. Vestibule, 2. Vestibular fold 3. Laryngeal

Ventricle, 4. Vocal fold, 5. Infraglottic cavity

TRUE FALSEFALSE The lateral borders are formed by the aryepiglottic folds

TRUE FALSE

VESTIBULE VENTRICLE RIMA GLOTTIDIS


On to SPOTTER PRACTICE

ARE YOU READY?• If you’re feeling confident move on to

tackle the mock spotter.GOOD LUCK!

• If you don’t feel quite ready, and want to review the material again,

click here to return to the homepage

1. Name Structure A

2. How does this structure enter the larynx?

3. What is structure A’s origin?

Left Recurrent Laryngeal Nerve

It ascends in the groove between the trachea and the oesophagus and pierces the inferior constrictor of the pharynx to enter the larynx

It is a branch of the Left Vagus

SPOTTER PRACTICE 1A

SPOTTER PRACTICE 2

1. Name structure B

2. What is it’s nerve supply

3. Describe structure B’s function

Cricothyroid muscle

External laryngeal nerve

Cricothyroid muscles pull the thyroid cartilage forwards and downwards to stretch and tense the vocal ligament so a higher pitched sound is produced

B

SPOTTER PRACTICE 31. Name Structure C

2. Which vertebral levels does C lie opposite?

3. Name structure D

4. To which group of muscles does structure D belong

Omohyoid muscle

C3- C5

Thyroid Cartilage

Infrahyoid musclesExtrinsic muscles

C D

TRACHEOSTOMY•A small transverse incision is made through the skin in the anterior neck, the infrahyoid muscles are moved laterally, and isthmus of thyroid gland is may need to be divided to gain access to the trachea.

•A window is made in the 2nd and 3rd tracheal rings, to allow a tracheostomy tube to be inserted, and allow passage of air.

• Tracheostomy are usually temporary, and the tube is removed after the required length of time.

•However some patients require long-term or permanent tracheostomies. These patients are unable to vocalize as expired air will bypass the vocal folds.

RLN DAMAGEThe action of the adductors overpower that of the single abductor muscle (SEMON’S LAW), this causes theaffected vocal cord to adopt a MIDLINE ADDUCTED POSITION

Both vocal cords will be adducted, and the patient will experience STRIDOR; harsh high-pitched wheezing

The innervation to the intrinsic muscles supplied on one side is disrupted, resulting in paralysis of that vocal cord, which then adopts a PARAMEDIAN POSITION midway between adduction and abduction.

Paralysis of both vocal cords results in complete loss of the voice (aphonia). Lack of muscle power to hold open the rima glottidis leads to breathing difficulties

The RLN is at risk of damage during thyroid surgery.The left RLN is more prone to damage as it is longer and has a thoracic course.

ASPIRATION OF FOREIGN BODIES•The VALLECULAE and PIRIFORM FOSSAE are common sites for lodging of food on it’s passage to the pharynx.

•Occasionally food or other foreign bodies may pass through into the laryngeal inlet, and become lodged above the vestibular folds.

•This causes the laryngeal muscles to go into spasm, causing the vocal cords to tense and complete closure of the rima glottidis- preventing entry of air into the lungs.

•Asphixiation will occur if the obstruction is not removed, so emergency action needs to be taken to open the airway.

HEIMLICH MANOEVRE •This involves sudden compression of the patient’s abdomen, which elevates the diaphragm, causing compression of the air-filled lungs. This allows air to be expelled from the trachea

• The force of this expired air is likely dislodge the obstruction

CRICOTHYROTOMY•Performed in emergency situations

• If the airway is blocked above the level of the vocal folds by a foreign body, the membrane can perforated in the midline, to gain access into the infra-glottic cavity

• This allows air (to bypass the obstruction) into the trachea and lower air passages.

• Due it’s small size cricothyroid membrane puncture can only be a temporary intervention, it doesn’t allow for prolonged ventilation, and therefore should be followed by tracheostomy when possible or if needed

LARYNGOSCOPYThis procedure allows the interior of the larynx to be examined, and is useful in investigating problems of the voice, breathing , and swallowing.

INDIRECT LARYNGOSCOPY:- • Relatively simple procedure that involves holding a laryngeal mirror against the soft palate at the back of the throat, allowing view through the inlet.

DIRECT LARYNGOSCOPY

• Fibre-optic laryngoscope is a flexible instrument that is usually inserted through the nose into the pharynx, useful when the mirror doesn’t give an adequate view. Can be used under local anaesthetic.

• Rigid Laryngoscope is inserted into the mouth and larynx. It is used under general anaesthetic in operating theatres. The procedure allows for collection of tissue samples or removal of foreign bodies.

CORRECT!

INCORRECT

"learning the larynx"

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