Anatomy of larynx

larynx• A cartilaginous structure present in front of

C3-C6

• About 5cm in long in adults

• Shorter and higher in women and children

• Moves on deglutition(*)

• Primary function is sphincteric in nature

• Organ of phonation

• The typical male voice develops only at puberty

Skeleton of larynx

• Thyroid cartilage,cricoid cartilage and epiglottis

(unpaired cartilages)

•Arytenoids,corniculates and cuneiforms(paired)

Thyroid cartilage

Front view Side view

Thyroid angle(laryngeal prominence)

• 900 in males

• 1200 in females

Cricoid cartilage

Posterior view Side view

epiglottis

Membranes and ligaments

arytenoids

False vocal cords(vestibular folds)• Lower borders of

quadrangular membrane(vestibular ligament)

• Present above and lateral to the true vocal cords

• Pinkish in appearance• (vascular)

F F

True vocal cords

• Upper borders of conus elasticus

• Involved in phonation• Pearly white in

appearance• Present below and

medial to false vocal cords

Conus elasticus• Crico-thyro-arytenoid

ligament• Its free upper border

is the fibrous ligament of the true vocal cord

Cavity of larynx• Divided into 3 parts

by these vocal cords• 1.vestibule• 2.sinus (ventricle)• 3.infraglottic cavity

Rima glottidis(glottis)• Space between the

two vocal cords(true vocal cords)

• Directly concerned with voice production

• Rima vestibuli is the space between the false vocal cords

Saccule of larynx• Extension from sinus• Secretes mucus to

keep the vocal cords lubricated.

Intrinsic muscles

• These help in

• opening and closing the glottis ,

• altering the length and tension of the vocal cords and

• closing the inlet.

• All are supplied by recurrent laryngeal nerve except cricothyroid(supplied by external laryngeal nerve)

Inlet of larynx• Opens superiorly into

laryngopharynx• Oblique• leads to vestibule of

larynx

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P

Muscles of inlet• oblique arytenoids,

transverse arytenoid and aryepiglottic muscles

• close the inlet during swallowing

Bending of epiglottis(during deglutition)

Tensor of the vocal cord• Cricothyroid muscle is the

“tensor of the vocal cord”• The only intrinsic muscle

placed externally• Tilts “the thyroid cartilage

forwards” and the arytenoids backwards”

• so that vocal cords become longer

Cricothyroid in action

Muscles of the vocal cords• Posterior crico

arytenoid(5 in the pic) is

• The ONLY ABDUCTOR of the vocal cords and keeps the airway open

• (life saving muscle!!)

The abductor in action

Superior view

Muscles closing the glottis(adductors)

Lateral cricoarytenoid muscles

Relaxers of the vocal cords

Main relaxers areThyro arytenoid muscles

A part of this muscle is called“vocalis”

Movements of vocal cords

During speech(adducted)

During breathing(abducted)

stemband[1].avi

Office view

Operating view

Apex should be anterior

Blood supply and nerve supply of larynx

• true Vocal cords are reference points

• Up to the cords supplied by superior laryngeal artery(br.of superior thyroid)

• Below the cords supplied by inferior laryngeal artery

•Up to the cords sensory nerve is

• internal laryngeal nerve(of X) (1in fig)

•Below the cords, sensory nerve is

• the Recurrent laryngeal nerve(of X)(3in fig)

1

2

3

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laryngoscopyA

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Vocal cord paralysis

Injury to recurrent laryngeal nerve causes paralysis of theipsilateral cord(same side)

Usually the left rec.laryngeal.nerve is affected(?)So the left cord is paralyzed

SEMON’S LAW

• In recurrent laryngeal nerve injury the abductor is the first to paralyze and last to recover.

summary

cu

cor

From behind(mucosa intact)Mucosa removed

Trachea

Trachea

• Wide,fibrocartilaginous tube beginning at C6

• Lies anterior to esophagus and in the superior mediastinum inclines to the right side.

• and ends by dividing into right and left principal bronchi at the level of sternal angle.

Tracheal rings(15-20)

carina

The carina is the upwardly directed ridge seen internally at the bifurcation

and is a landmark during bronchoscopy

relations

Right bronchus is directly in line with trachea

Bronchial tree

Applied anatomy• tracheostomy• Tracheo bronchial lymph nodes and carina• (lung’s lymphatic drainage)

1.Can you see the tracheal shadow and principal bronchi?

2.Male or female?

http://anatomy.med.umich.edu/surface/cardinal/cardinal.html

Check for all surface anatomy and eye movements