Larynx

• • Larynx aka voice box, has a cartilaginous skeleton composed of several structures
  • These principal cartilages form framework of larynx and play crutial role in breathing, phonation and protect trachea against food aspiration.

  Cartilages of larynx can be classified into pair and unpaired

  1. Paired: Arytenoid, Corniculate, cuneiform
  2. Unpaired: Thyroid, cricoid and epiglottis.

  
• Thyroid cartilage


  Largest and most prominent cartilage in larynx
• Thyroid cartilage

  • V-shape in cross-section
  • Consist of right and left lamina that meet in midline at an angle, forming laryngeal prominence
  • Each lamina is roughly quadrilateral, lower part of anterior border form laryngeal prominence
  • Upper part of anterior border do not fuse and are separated by thyroid notch
  • Posterior borders are free, they are prolonged upwards and downwards as superior and inferior horns
  • Superior horn connects with hyoid bone via thyrohyoid membrane
  • Inferior horn articulate with cricoid cartilate forming cricothyroid joint
• Thyroid cartilage

  • Outer surface of each lamina is marked by an oblique line which provides attachment for thyrohyoid, sternothyroid and thyropharyngeus partbof inferior constrictor of pharynx.

  
• Cricoid cartilage

  • Ring shape: complete cartilage
  • Encircles larynx bellow thyroid cartilage and forms foundation stone of larynx
  • Thicker and stronger and thyroid cartilage
  • The ring has narrow anterior part called arch and broad posterior part called lamina
  • Anterior arch gives origin point for cricothyroid m.
  • Anterolateral aspect of anterior arch gived origin to lateral cricoarytenoid muscle
  • Posterior lamina provides attachment sites posterior cricoarytenoid muscles

  
• Epiglottic cartilage

  • Leaf-shaped cartilage positioned at roof of tongur above glottis.
  • Structure: upper end is broad and free and projects upwards and backwards behing tongue and hyoid bone. Lowercend (thyroepiglottic lig.) is anchor to inner aspect of thyroid cartilage
  • Attached to thyroid cartilage via thyroepiglottic lig and hyoid bone via hyoepiglottic lig.
  • Thyroepiglottic muscle is attached btw thyroid cartilage and margins og epiglottis. Keeps inlet of larynx patent for breathing
  • Aryepiglotic muscle closes inlet during swallowing

  
• During swallowing epiglottis acts as a flap that folfs back over glottis, which is the openinh between the vocal cords. This action prevents food and liquids from entering trachea and directs them towards esophagus.