Download MBBS Anatomy PPT 25 Ent Larynx Notes

STRIDOR

Harsh, high-pitched musical

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sound

Produced by turbulence of airflow

through a partial obstruction in

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the airway passage

ANATOMY OF LARYNX

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Situated in midline of neck from the level

of C-3 to C-6 vertebrae lying in front of

laryngopharynx.

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LARYNX

? Musculocartilagenous structure,

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? Lined with mucous membrane

? Connected to pharynx and superior part of

trachea

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? Acts as essential sphincter guarding entrance

into trachea

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? Secondarily function as organ of voice

? Formed of nine cartilages connected by ligaments

and muscles

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Topography of the extrinsic musculature of the

larynx

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ADAM'S APPLE

At puberty male larynx increases in size

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rapidly, and the thyroid cartilage projects

to form the Adam's apple.

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CACARTILARTILAGEGESS OFOF LA

RYR

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CAVITY OF LARYNX

EXTENT- from laryngeal inlet above to

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lower border of cricoid cartilage.

Inlet of larynx communicates with

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laryngopharynx.

CAVITY OF LARYNX

Divided into three parts by 2 folds of

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mucus membrane: False cords and True

vocal cords

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Parts are Vestibule, ventricle and

subglottic space

Glottis is the opening between vocal

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folds


MUSCLES OF LARYNX- INTRINSIC

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HISTOLOGY OF LARYNX

Mucous membrane lines the entire larynx.

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Stratified squamous epithelium lines true

vocal cords and upper parts of vestibule.

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Pseudostratified Columnar ciliated

epithelium lines rest of the cavity.

Mucous glands preset in all parts except

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on free edges of vocal cords

LYMPHATIC DRAINAGE

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SUPRAGLOTTIS-pre-epiglottic and upper

deep cervical nodes.

GLOTTIS-Lymphatics are practically

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absent

SUBGLOTTIS-prelaryngeal and

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pretracheal nodes also lower deep

cervical nodes

LARYNX OF AN INFANT DIFFERENT FROM ADULT

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Infant's larynx is positioned high in the neck opposite C3 or

C4 (vocal cord level ) at rest and reaches C1 or C2 during

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swal owing.
This high position al ows the epiglottis to meet soft palate

and make a nasopharyngeal channel for nasal breathing

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during suckling.
The milk feed passes separately over the dorsum of

tongue and the side of epiglottis, thus al owing breathing

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and feeding to go on simultaneously.

LARYNX OF AN INFANT
LARYNX OF AN INFANT DIFFERENT FROM ADULT

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Laryngeal cartilages are soft and col apse easily.

Epiglottis is omega-shaped and arytenoids

relatively large covering significant portion of

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the posterior glottis .

LARYNX OF AN INFANT DIFFERENT FROM ADULT

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Thyroid cartilage in an infant is flat.

It also overlaps the cricoid cartilage and is in turn

overlapped by the hyoid bone.

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Thus cricothyroid and thyrohyoid spaces are narrow and not

easily discernible as landmarks when performing

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tracheostomy.

LARYNX OF AN INFANT DIFFERENT FROM ADULT

Infant's larynx is smal and conical. The diameter of cricoid

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cartilage is smal er than the size of glottis, making

subglottis the narrowest part.

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It has a bearing in the selection of paediatric endotracheal

tube.

In adults, subglottic-glottic dimensions are approximately

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same and larynx is cylindrical.

LARYNX OF AN INFANT DIFFERENT FROM ADULT

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Submucosal tissues of infant's larynx are comparatively
loose and easily undergo oedematous change
with trauma or inflammation leading to obstruction.

Infant's larynx shows two spurts in growth. In the first

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three years of life larynx grows in width and length, and
thus obviates the need for any airway surgery in certain
congenital anomalies.
LARYNX OF AN INFANT DIFFERENT FROM ADULT

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The second spurt in growth occurs
during adolescence when the thyroid angle

develops. The length of vocal cords then

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increases leading to voice
changes associated with puberty.
With growth of the neck, larynx gradual y

descends to adult

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position opposite Cs (vocal cord level).

LARYNX OF AN INFANT DIFFERENT FROM ADULT

In childhood, vocal cord is 6 mm in

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females and 8 mm in males.
It increases to 15-19 mm in adult females

and

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17-23 in adult male.
Adult male voices are usual y lower-pitched

and have larger folds.

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INFANT AIRWAY

The subglottic diameter measures

approximately 4.5

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A diameter of less then 3.5 mm suggests a

marginal subglottic airway and is consistent

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with subglottic stenosis

INFANT AIRWAY

?Circumferential mucosal edema of 1 mm within the larynx

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of an infant causes a glottis to narrow by over 60% to

75%.

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LOCATION OF OBSTRUCTION

Stridor can be localized to discrete areas of the

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airway according to the nature of the sound

in relationship to the phase of breathing

LOCATION OF OBSTRUCTION

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These discrete regions can be divided into three

zones

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Supraglottic and supralaryngeal zone which includes the

pharynx

Extrathoracic tracheal zone including both glottis

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subglottis and cervical trachea

Intrathoracic tracheal

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zone which includes

primary and secondary bronchi

LOCATION OF OBSTRUCTION

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Supraglottis or Pharynx - Inspiratory and high- pitched-

Glottis and Subglottis (extrathoracic tracheal zone)-

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Biphasic of intermediate pitch

Intrathoracic tracheal/bronchial zone- Expiratory often

confused with wheezing

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ANATOMY OF TRACHEA

Tube made up of cartilage and membrane

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and measures approx 10-11cm in adult

Extends from C-6 to T-5
There are 16-20 incomplete cartilaginous

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rings. In neck 6-7 rings are present.


BLOOD SUPPLY

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The inferior thyroid vessels and their

tracheoesophageal branches provide blood

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supply to the proximal trachea while the

bronchial arteries vascularize the distal

trachea, carina, and main bronchi

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The trachea is also supplied by smal branches

originating from the subclavian artery, internal

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mammary artery, and innominate artery.

VENOUS AND LYMPHATIC DRAINAGE

Venous drainage is through the azygos and

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hemi azygos systems while lymphatic

drainage is through the low and high

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paratracheal nodal chains eventual y

reaching the deep cervical nodes.

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NERVE SUPPLY

Vagus, recurrent laryngeal nerve and

sympathetic trunk

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LYMPHATICS

Pretracheal and paratracheal lymph nodes