Larynx

Larynx

1. Joints

   • cricoarytenoid
     • saddle joint that permits rocking motion and limited gliding
     • cricoid articular facet
       • elliptical, convex, directed downward 25 degrees located on superior border of the cricoid lamina
     • arytenoid articular facet
       • circular, sharply concave located on the under surface of muscle process
   • cricothyroid
     • one of 3 ligaments responsible for gliding motion, vf tension, and increase of pitch

2. hyoid bone

   • larynx is suspended form
   • U Shaped
     • horns
       • greater cornua
       • lesser cornua
   • suprahyoid
     • widen the pharynx and close off the trachea during swallowing
     • digastric
       • origin: mastoid process insertion: hyoid bone
     • stylohyoid
       • origin: styloid process insertion: hyoid bone
     • mylohyoid
     • geniohyoid
       • origin: thyroid cartilage insertion: hyoid bone
   • infrahyoid
     • draw hyoid bone downward and larynx
     • omohyoid
       • origin: superior border of scapula insertion: hyoid bone
     • sternohyoid
       • origin: mabubrium of sternum insertion: hyoid bone
     • sternothyroid
       • origin: manubrium insertion: thyroid cartilage
     • thyrohyoid
       • origin: thyroid cartilage insertion: hyoid bone

3. Cartilage

   • 9 total, 3 unpaired and 3 paired
   • paired
     • arytenoid
       • hyaline muscular process is point of attachment
       • base
         • vocal process
           • vocal ligament
       • apex
       • 3 surfaces
         • posterior surface
         • anterolateral
         • medial
     • corniculate
       • elastic
     • cuneiform
       • elasticfolds of mucous membrane encloses ligaments and muscle fibers entrance to the larynx wedge shaped rods
       • aryepiglottis folds
       • cuneiform tubercules
         • lend support to aryepiglottis folds
         • connective tissue
         • fat
         • mucous membrane
   • unpaired
     • thyroid
       • hyaline largest, shield like
       • 2 thyroid laminae
         • fused together thyroid notch allows for incomplete fusion
         • thyroid notch
           • adams apple 80 degrees in males 90 in females
       • superior horns
         • directed upward and back medially
       • inferior horns
         • shorter, thicker directed downward
     • cricoid
       • hyaline located above first tracheal ringdiathrodial pivot joint- allows for rotation which is important for pitch changing attaches by cricotracheal membrane
       • anterior arch
       • posterior quadrate lamina
     • epiglottis
       • elastic flexible, leaf life   trap door prevents food from entering larynx
       • petiolus
         • small straw like structure attached to thyroid cartilage at thyroid notch
       • hypoepiglottic ligament
         • broad part where it attaches to hyoid bone
       • glossoepiglottic ligaments
         • two lateral fold attaching to the root of the tongue
         • valleculae
           • 2 pits seen between epiglottis and the root of the tongue one either side of the median
       • fat pad
         • separates epiglottis and hyoid bone form thyroid cartilage

4. Muscles

   • intrisnic
     • lateral cricoarytenoid muscle ( LCA)
       • relaxer closes the glottis shapes it for a whisper fan shaped
     • interarytenoids
       • oblique, transverse approximate the arytenoid cartilages and regulate medial compression
       • transverse
         • approximates arytenoid cartilages by sliding along axis toward midline horizontal direction
     • cricothyroid muscle
       • tensor elongate vf fan shpaed
       • par oblique
         • lower course upward
       • par recta
         • upper course vertical
   • extrinsic
     • sternothyroid
       • draws thyroid cartilage downward
     • thyrohyoid
       • contraction decreases distance between thyroid cartilage and hyoid bone
     • pharyngeal contstrictor
       • parynx
   • Supra hyoid mucles
     • influence larynx indirectly
     • diagastic
       • two bellies joined by intermediate tendon tendon is attached by greater horn of the hyoid bone
       • anterior belly
         • lower madible
       • posterior belly
         • mastoid process
     • stylohyoid
       • long slender styloid process contraction draws hyoid bone up and backward
     • mylohyoid
       • inner surface ridge mandible elevates floor of mouth, hyoid bone, and tongue
     • geniohyoid
       • pair of cylindrical muscles above the mylohyoid indirect contact with one another when mandile is fixed it pulls it up and forward mental symphasis
   • infra hyoid muscles
     • sternohyoid
     • omohyoid

5. membranes

   • extrinsic
     • bounds larynx to hyoid bone and trachea
     • hyothyroid
       • space between inferior border of hyoid bone and superior thyroid cartilage bridges cornu
     • hyoepiglottic
       • elastic, unpaired, midline connects corpus or epiglottis to upper posterior surface of corpus hyoid bone
     • cricotracheal ring
       • binds cricoid cartilage to 1st tracheal ring
   • intinsic
     • not as distinct same continuous layer entire interior of the larynx
     • elastic membrane
       • conus elasticus
         • cricoid liagments
           • medial
             • well defined band of yellow elastic tissue midline cricoid arch to thyroid cartilage
           • lateral
             • 2 begin at lateral margins
         • vocal ligament
           • anchor for vf
       • quandrangular
         • upper paired membrane, around thyroid cartilage thickens ventricular ligaments superior portion is the aryepiglottic folds
         • vernticular ligaments
           • got to the arytenoid cartilage from the triangular fovea two ligaments that come together at interior thyroid (approximate) help true vf
         • epiglottic folds