Anatomy Of Larynx

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

A

• Opens superiorly into laryngopharynx • Oblique • leads to vestibule of larynx

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 are Thyro arytenoid muscles A part of this muscle is called “vocalis”

Movements of vocal cords

During speech(adducted)

During breathing(abducted)

stemband[1].avi

Apex should be anterior

Office view

Operating view

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

laryngoscopy A

P

Vocal cord paralysis

Injury to recurrent laryngeal nerve causes paralysis of the ipsilateral 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