Larynx

Larynx


LARYNX

  • The Larynx is an apparatus made up of cartilage, ligaments, muscles, and mucous membrane.
  • Guards the entrance to the lower respiratory passages  (trachea, bronchi, and lungs) and houses the vocal cords.
DEVELOPMENT OF LARYNX
  • Occur during the 4th week of intra uterine life.
  • The respiratory primordium appears in the floor of the foregut in the 4th  week of gestational life.
  • The larynx begins as a slit like diverticulum (laryngotracheal groove ) in the ventral wall of the  primitive pharynx .
  • The groove gradually deepens and its edges fuse to form a septum,which separates the laryngotracheal tube from the pharynx and oesophagus.
  • The process of this fusion starts caudally and extend cranially
  • Between 5th & 6th weeks, — 3  swellings appear at the laryngeal aditus.
  • An anterior swelling , a derivative of the hypobranchial eminence from 4th arch—forms Epiglottis.
  • 2 lateral arytenoid swellings appear, derived from the 6th  branchial arch, move medially and form a T-shaped aperture
  • Laryngeal  lumen— temporarily occluded  at 8 weeks gestational age as a result of  epithelial proliferation.
  • By the 10th week of gestation, recanalization occurs and consequently pair of  laryngeal ventricles are formed. 
  • The laryngeal ventricles are bound by  mesenchyme tissue that  condense and progress into false and true vocal cords.
  • Laryngeal  cartilages develop from the mesenchyme of the branchial arches.
  • Thyroid  cartilage— from the 4th  arch mesenchyme  as two lateral plates meet in the midline.
  • Arytenoids , Corniculate , Cricoid & Tracheal cartilages–  6th  branchial  arch
  • Epiglottis —  develops  from Hypobranchial eminence
  • Intrinsic  laryngeal muscles develop from the mesoderm of the 4th and 6th  arches
EXTERNAL FEATURES OF LARYNX:
  • Larynx is located anterior to the 3rd, 4th, 5th, and 6th cervical vertebrae.
  • Extends from the base of the tongue to the proximal portion of the trachea.
  • Laryngeal  skeleton is suspended from the hyoid bone by the medial and  lateral thyrohyoid membrane.
  • The 3rd to 6th cervical vertebrae, prevertebral muscles, and fascia lie posterior to the larynx.
  • Laryngofissure is opening of larynx in midline.
INTERNAL FEATURES OF 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:

  1. Supraglottic 
  2. Glottic
  3. Subglottic spaces

DIFFERENCE B/W ADULT & INFANT LARYNX:

  • Size-  smaller in infants
  • Shape–  funnel shaped in infants , cylindrical in  adults
  • Softness– laryngeal cartilages are softer in infants
  • Superiorly placed  in infants helps child to breathe  & suckle at same time
  • Straighter and less oblique than in adults
  • Sensitivity is greater in infants more prone to spasm
  • Sub glottis is very narrow ,even a small swelling can lead to airway obstruction in infants
  • The narrowest part of the infantile larynx is the junction of subglottic larynx with trachea and this is because cricoid cartilage is very small
 LARYNGEAL FRAMEWORK:
  1. Cartilages
  2. Joints
  3. Ligaments
  4. Membranes
  5. Muscles
  6. Mucous membrane
  7. Hyoid Bone
Exam Question
 
  • Superiorly placed larynx  in infants helps child to breathe & suckle at same time.
  • Larynx is funnel shaped in infant
  • Larynx is cylindrical shaped in adults
  • Cricoid Cartilage is the narrowest part of infantile larynx.
  • Laryngofissure is opening of larynx in midline.
Don’t Forget to Solve all the previous Year Question asked on Larynx

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