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:
- Supraglottic
- Glottic
- 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:
- Cartilages
- Joints
- Ligaments
- Membranes
- Muscles
- Mucous membrane
- 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