Anatomy Of Larynx

Principal Internal Features of the Larynx

The cavity of the larynx extends

above – from the area of the tip of the epiglottis,aryepiglottic folds, and interarytenoid folds

below — to the 1st tracheal ring

Internal cavity of the larynx

divided into 3 spaces:

• Supraglottic,

• Glottic, And

• Subglottic spaces

Intrinsic Membranes• connect the laryngeal

cartilages with each other to regulate movement.

• There are 2 intrinsic membranes :

1. Conus Elasticus and 2. Quadrangular

membranes.

CONUS ELASTICUS

• Conus Elasticus connects the cricoid cartilage with the thyroid and arytenoid cartilages.

• composed of dense fibroconnective tissue with abundant elastic fibers.

CONUS ELASTICUS• Having 2 parts 1 .Medial cricothyroid ligament connects the anterior part of the arch of the cricoid cartilage with the inferior border of the thyroid cartilage. 2. Lateral cricothyroid membranes originate on the superior surface of the cricoid arch and rise superiorly and medially to insert on the vocal process of the arytenoid cartilages posteriorly, and to the interior median part of the thyroid cartilage anteriorly.• Its free borders form the VOCAL

LIGAMENTS

Quadrangular Membrane• Extends from the sides of

the epiglottic cartilage anteriorly to the anterolateral surface of the arytenoid cartilage and posteroinferiorly to the corniculate cartilage.

• With its covering of mucous membrane forms the aryepiglottic fold superiorly and vestibular ligament inferiorly.

• it forms the medial wall of the piriform recess

• The paired Quadrangular Membranes connect the epiglottis with the arytenoid and thyroid cartilages.

• Course posteriorly downward and attach to the corniculate cartilages and the lateral surfaces of the arytenoids.

• The cuneiform cartilages are embedded within the aryepiglottic folds.

• The free inferior borders of the quadrangular membranes form the ventricular ligaments, also known as the false vocal folds.

Intrinsic laryngeal muscles

1. Abductors of the vocal cords.2. Adductors of the vocal cords.3. Tensors of the vocal cords.4. Openers of laryngeal inlets.

Intrinsic Muscles

• The intrinsic muscles are: Cricothyroid Posterior cricoarytenoid Lateral cricoarytenoid Arytenoid with its

transverse and oblique fibers

Thyroarytenoid and its thyroepiglottic and components

Abductors of the vocal cordsPosterior crico-arytenoid muscle.originate from posterior surface of the lamina of cricoid cartilage.run superolaterally to converge on the muscular processes of the arytenoid cartilage.abduction and externally rotate the arytenoid cartilage to open the rima glottidis.are innervated by recurent laryngeal branches of the vagus nerve (CN X).

Posterior crico-arytenoid muscle

Adductors of the vocal cords

• Are 3 on each side:1. Lateral crico-arytenoid muscle.2. Transverse portion of interarytenoid muscle.3. External portion of thyro-arytenoid muscle.

Lateral crico-arytenoid muscle

Lateral crico-arytenoid muscle• originates from the upper

surface of the arch of the cricoid cartilage.

• runs posterosuperiorly to insert on the muscular process of the arytenoid cartilage.

• adduct and internally rotate the arytenoid cartilage- adducted vocal folds with an open air channel posteriorly between adjacent arytenoid cartilages.

• are innervated by the recurrent laryngeal branches of the vagus nerve (CN X).

Transverse portion of interarytenoid muscle

• is a single muscle.• spans the distance

between adjacent lateral margins of the arytenoid cartilages and covers the posterior surfaces of these cartilages.

• is innervated by the recurrent laryngeal branches of the vagus nerve (CN X).

External portion of thyro-arytenoid muscle

• are broad flat muscles lateral to the fibro-elastic membrane of the larynx and the laryngeal ventricles and saccules.

• run from a vertical line of origin on the lower half of the thyroid angle and adjacent external surface of the cricothyroid cartilage.

• Some of the fibers may continue into the aryepiglottic fold and reach part of thyro-epiglottic muscle.

Thyro-arytenoid muscle

Tensors of the vocal cords

1. Cricothyroid muscle ( external tensor).2. Internal portion of thyro-arytenoid (vocalis

muscle).

Cricothyroid muscle (external tensor)

• are fan-shaped muscles.• are attached to the arch of the

cricoid cartilage and attach to the thyroid cartilage.

• have two parts; oblique and straight.

• Oblique part runs in a posterior direction from the arch of the cricoid cartilage to the inferior horn of the thyroid cartilage.

• Straight part runs more vertically from the arch of the cricoid cartilage to the posteroinferior margin of the thyroid lamina.

Action of cricothyroid muscle

• move the cricothyriod joints.• pull the thyroid cartilage forward

and rotate it down relative to the cricoid cartilage-lengthen the vocal folds.

• increases the distance between the angle of the thyroid cartilage & the vocal processes of the arytenoid cartilages, and results in increase in the length & tension of the vocal cords

• are the only one intrinsic (lies outside) muscles innervated by the superior laryngeal branches of the vagus nerve (CN X).

Internal portion of thyro-arytenoid (vocalis muscle)

• are elongate muscles lateral to and running parallel with each vocal ligament.

• attaches posteriorly to the lateral surface of the vocal process and adjacent depression on the anterolateral surface of the arytenoid cartilage.

• insert anteriorly along the length of the vacal ligament to the thyroid angle.

• pulls the arytenoid cartilage forward toward the thyroid cartilage and thus shortens and relaxes the vocal cords

• adjust tension in the vocal folds.• are innervated by the recurrent laryngeal

branches of the vagus nerve (CN X).

Openers of the laryngeal inlet

Thyro-epiglottic muscle are broad flat muscles

lateral to the fibro-elastic membrane of the larynx and the laryngeal ventricles and saccules.

run from a vertical line of origin on the lower half of the thyroid angle and adjacent external surface of the cricothyroid cartilage.

Some of the fibers may continue into the aryepiglottic fold and reach part of thyro-epiglottic muscle.

Closers of the laryngeal inlet.Oblique portion of interarytenoid muscle

• are pair muscles.• run from the posterior surface of the

muscular process of one arytenoid cartilage to the apex of the arytenoid cartilage on the other side.

• Some fibers of this muscle continue laterally around the margin of the arytenoid cartilage and into the aryepiglottic fold to continue as part of aryepiglottic muscle.

• can narrow the laryngeal inlet by constricting the distance between the arytenoid cartilage and the epiglottis.

• is innervated by the recurrent laryngeal branches of the vagus nerve (CN X)

Closers of the laryngeal inletAryepiglottic muscle

Cavity of the larynx

2 folds

1. False vocal cord.2. True vocal cord.

3 parts

1. Vestibule.2. Ventricle.3. Subglottic space

• Extends from the inlet of the larynx to the lower border of the cricoid cartilage, it is divided into 3 parts by 2 folds of mucous membrane:

Ligaments & Folds OF Larynx

• Epiglottic ligaments

• Aryepiglottic fold

• Vestibular ligament (vestibular folds or false vocal cords)

• Vocal ligaments

1 . Epiglottic Ligaments and Folds

• Hyoepiglottic ligament

• Thyroepiglottic ligament

• Median glossoepiglottic ligament

• Lateral glossoepiglottic or pharyngoepiglottic fold,

• attached between the base of the epiglottic cartilage and the pharyngeal wall at the root of the tongue

2 . Aryepiglottic Folds

• one on each side,• contain the aryepiglottic

muscles. • associated with the superior

border of the quadrangular membrane.

• Both aryepiglottic folds constrict the entrance to the larynx and protect the respiratory pathway by not permitting food, liquids, and foreign bodies to enter the larynx and trachea.

3 . Vestibular Folds (False Vocal Cords)

• formed by the inferior edge of the quadrangular membrane.

• Attached in front to the thyroid cartilage just below the attachment of the epiglottic cartilage

• Connected behind to the anterolateral surfaces of the arytenoid cartilages.

• The vestibular ligaments are located just above the vocal ligaments, separated from them by bilateral ellipsoid spaces called the laryngeal ventricles.

• Overlap the true vocal folds just prior to a cough or sneeze — reinforcing the resistance offered by the true vocal folds against the internal expiratory pressures.

4.Vocal Ligaments, Vocal Cords, and Vocal Folds

• The thickened, ligamentous, upper edges of the elastic tissue of the conus are the vocal ligaments or vocal cords.

• Extend from the medial extremities of the laminae of the thyroid cartilage in the midline anteriorly (forming the anterior commissure) to the apices of the vocal processes of the arytenoid cartilages on each side posteriorly.

Structure of Vocalcord

• Histologically 5 layers: • LAYER 1: is the squamous epithelial lining. It is very thin and helps to hold the shape of

the vocal fold. This layer doesnot contain any mucous glands.• LAYER 2: superfical layer of the lamina propria. It is composed of loose fibers and

matrix .• This layer contains only minimal elastic and collagenous fibers and offers least

resistance to vibration. The integrity of this layer is vital for proper phonatory function. • LAYER 3: intermediate layer of lamina propria.• It contains a higher concentration of elastic and collagenous fibers when compared to

layer 2. This layer is thickened at the anterior and posterior ends of the vocal folds. These thickened regions are known as anterior and posterior macula flava. These structures provide protection to the vocal folds from mechanical damage.

• LAYER 4 : deep layer of lamina propria. • It contains a dense collection of elastic and collagenous fibers. This layer along with

the intermediate layer constitute the vocal ligament. Some of the collagenous fibers present here gets inserted into the vocalis muscle. LAYER 5: formed by the vocalis muscle. The fibers of this muscle run parallel to the direction of the vocal fold.

• Vocalis muscle is infact a portion of thyro arytenoid muscle.

• At the anterior most portion of the vocal fold a mass of collagenous tissue is present--known as the anterior commissure tendon or Broyle's ligament.

• This ligament gets attached to the inner area of thyroid cartilage which is devoid of perichondrium.

• Lacking a submucosa and blood vessels, the vocal ligaments appear to be pearly white and shiny.

• The space between the true vocal cords (the intermembranous space) is known as the rima glottidis

Surgical Considerations

• The epithelium of the true vocal cords does not have lymphatics. Therefore, metastatic disease is a rare phenomenon.

• The vocal folds are devoid of lymphatics, and it infact clearly forms the watershed zone between the upper and the lower group of lymphatics.

• The pathway of metastasis of glottic cancer is via the Delphian node or paratracheal nodes and finally nodes of the superior mediastinum.

Laryngeal Mucosa

• Is mostly of the respiratory type called ciliated columnar epithelium,

• certain areas of the larynx covered with stratified squamous epithelium are- upper area of the anterior , dorsal epiglottic surfaces, the ventral half of the aryepiglottic folds, and the vocal cords. • Mucous membrane of the supraglottic larynx is a downward

continuation of the oropharyngeal mucosa. • Infraglottic region of the larynx is made of normal respiratory

mucosa• Mucous glands are found at the posterior surface of the epiglottis,

aryepiglottic fold, and laryngeal appendices.

Laryngeal Spaces

• Internal laryngeal spaces :

vestibule, ventricles, subglottic or

infraglottic spaceso External laryngeal

spaces Paraglottic spacepre-epiglottic. Space

Internal Spaces (Laryngeal Cavity) VESTIBULE• pyramid -shaped space

extends from the laryngeal inlet or aditus to the vestibular folds (false vocal cords).

• Bounded ventrally by the posteroinferior surface of the epiglottis, dorsally by the corniculate cartilages and apices of the arytenoids, and laterally by the aryepiglottic folds and the piriform recesses.

Laryngeal Ventricles• Compsed of 2 parts1. Saccule.2. Rimaglottidis.• sinuses (of Morgagni), are

diverticula of the interval between the false and true vocal cords.

• It is lined internally by mucosa and covered externally by a very thin layer of elastic tissue and the thin thyroarytenoid muscle.

• The anterior end of the ventricle may possess an additional external expansion, the laryngeal saccule,

Saccule• The saccule is a conical

pouch which ascends from the anterior part of the ventricle

• It lies between the inner surface of thyroid cartilage and the false cords.

• Numerous mucous glands open onto the surface of its lining mucosa.

Rima glottidisSubdivided into 2 parts,

• Posterior 2/5 – intercartilaginous part (respiratory glottis,or interarytenoid space), between the arytenoid cartilages and

• Anterior 3/5 — the intermembranous part or glottis vocalis.

• Its average length: In the adult male is about 2.5 cm. In the adult female is about 1.6 cm.

Surgical Considerations.

• Enlargement of the laryngeal saccule is often referred to as a laryngocele.

• Any obstruction of the laryngeal ventricle, such as a ventricular carcinoma, may lead to the formation of a laryngocele.

• A laryngocele may bulge through the aryepiglottic fold and obstruct the endolarynx

( internal laryngocele ).• It may be present outside of the

thyrohyoid membrane ( external laryngocele ).

• The enlargement may even be a combined internal and external laryngocele

Subglottic (Infraglottic) Space

• the distal part of the laryngeal cavity.

• extends from the glottis to the inferior border of the cricoid cartilage.

• The subglottic space begins below the curve formed by the vocal fold to the lower end of cricoid cartilage

• SURGICAL IMPORTANCE :• Narrowest area in infants , so

edema obstruction & respiratory distress occur early

External Spaces

• Supraglottic laryngeal area is subdivided into 3 laryngeal spaces

• Paired Lateral Paraglottic Spaces

• One midline Pre-Epiglottic Space

Paraglottic Spaces (Tucker’s space)

• Bounded laterally by the thyroid cartilage,

• inferomedially by the conus elasticus,

• medially by the ventricle and the quadrangular membrane

Pre-Epiglottic Space ( Boayer’s space )

• Bounded superiorly by the hyoepiglottic ligament, anteriorly by the thyrohyoid membrane and ligament, and Posteroinferiorly by the epiglottis and thyroepiglottic ligament.

• The pre-epiglottic space forms an inverted pyramid.

• continuous with the superior portion of the paraglottic space.

• contains abundant fat, blood vessels, lymphatics,and mucosal glands.

Surgical Considerations

• Epiglottic (supraglottic) carcinoma may spread through perforations in the epiglottis into the pre-epiglottic space.

• Since the pre-epiglottic space communicates laterally with the paraglottic spaces, a carcinoma is free to spread beyond the internal boundaries of the larynx.

• Therefore, supraglottic laryngectomy may be contraindicated

Function of the Larynx

• is an elaborate sphincter for the lower respiratory tract.

• provides a mechanism for producing sounds.• adjusts the size of the ventricle cavity result from

changes in the dimensions of the rima glottidis, rima vestibuli, vestibule, and the laryngeal inlet.

• This changes result from the muscle actions and laryngeal mechanics.

During Quiet Respiration

• The laryngeal inlet, vestibule, rima vestibule and rima glottidis are open.

• The arytenoid cartilages are abducted.

• The rima glottidis in triangular shaped

During Force Respiration

• The arytenoid cartilage are rotated laterally, mainly by action of the posterior crico-arytenoid m.

• As a result, the vocal folds are abducted, and the rima glottidis widens into a rhomboid shape, which effectively increases the diameter of the laryngeal airway.

Phonation• Arytenoid cartilages and vocal

folds are adducted and air is forced through the closed rima glottidis.

• This action causes the vocal folds to vibrate against each other and produce sounds, which can then be modified by the upper parts of the airway and oral cavity.

• Tension in the vocal folds can be adjusted by the vocalis and cricothyroid muscle.

Effort Closure

• occurs when air is retaind in the thoracic cavity to stablize the trunk, for example during heavy lifting, or as part of the mechanism for increasing intra-abdominal pressure.

• During effort closure, the rima glottidis is completely closed, as is the rima vestibuli and lower parts of the vestibule.

• The result is to completely and forcefully shut the airway.

During Swallowing• The rima glottidis, the rema

vestibuli, and vestibule are closed and the laryngeal inlet is narowed.

• The larynx is move upward and forward causes the epiglottis to swing downward towards the aryngeal inlet (also facilitate closing the laryngeal inlet and opening the esophagus).

• All these actions together prevent solids and liquids from entry into the airway and facilitate their movement through the piriform fossae into the esopahgus.

Blood supply of the larynx

1. Laryngeal branches of the superior thyroid artery.

2. Laryngeal branches of the inferior thyroid artery.

3. Cricothryoid branches of superior thyroid artery (cross the midline at the upper part of the cricothyroid membrane).

Blood supply of the larynx

Inferior thyroid artery

superior thyroid artery

Nerve supply of the larynx

supplied by branches of vagus

• Superior laryngeal nerve, has 2 branches:

1. Internal.2. External.

• Recurrent (Inferior) laryngeal nerve :

1. Anterolateral (motor)2. Posteromedial(sensory)

Superior laryngeal nerveExternal branch

• Travel down on the inferior constrictor muscle of the pharynx.

• Supplies the cricothyroid muscle and part of the anterior subglottis.

Suprior laryngeal nerve Internal branch

-Entirely sensoy. - Pierces the

thyrohyoid membrane with the superior laryngeal artery and vein.

-Supplies the cavity of the larynx as far down as the level of the vocal cords.

Recurrent (Inferior) laryngeal nerve

• longer coarse on the left.

• In the left it turns round the arch of the aorta.

• On the right it turns round the subclavian artery.

• In the neck it lies between the trachea and the oesophagus

Recurrent (Inferior) laryngeal nerve

• Its terminal part passes upward, under cover of the ala of the thyroid cartilage immediately behind the inferior cricothyroid joint, it then divided into:

1. Anterolateral (motor) branch which supplies all the intrisic muscles of the larynx except cricothyroid muscle.

2. Postromedial (sensory) branch which supplies the cavity of the larynx below the level of the vocal cords.

Lymphatic drainage of the larynx• Vocal cord has no lymphatic vessels.• The edges of the vocal cord divide the lymphatic

of the larynx into 2 parts:1. Supraglottic drain into:

2. Subglottic drain into:

Pre-epiglottic nodes. Upper deep cervical nodes.

•Prelaryngeal and pretracheal nodes.•Lower deep cervical.

Lymphatic drainage of the larynx

Symptoms of laryngeal disease• Generally the laryngeal diseases are characterized by:1. Hoarseness of the voice which means rough voice, maybe a

manifestation of any laryngeal disease whether congenital, traumatic, inflammatory, or neoplastic, or as a systemic disease as hypothyroidism , lung cancer.

2. Stridor: this is produced by the turbulence of diminished air flow at the nearly completely or partially obstructed larynx in the form of musical sounds, it’s usually inspiratory at the supraglottic and glottic and by phasic in the subglottic down to the carrina, expiratory stridor (wheez) at the lower air passages.

3. Aspiration: inhalation of the food or saliva due to failure of the protective sphencteric function of the larynx manifested as chocking or coughing during swallowing or chest infection due to saliva soiling in the lungs.

4. Pain: it maybe felt in the larynx or referred to the ear (otalgia) through IX & X CN.

Signs of laryngeal disease1) Voice abnormality (dysphonia): abnormal voice

ranging from aphonia to hoarseness of voice.2) Stridor.3) Mobility: laryngeal mobility due to swallowing

and phonation (which is normally palpable) may be impalpable in laryngeal disease.

4) Neck lump: this is maybe due to lartngeal disease itself or metastasis to the neck lymphnodes.