Larynx

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Larynx
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• Dr. Hassan Shaibah

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The pharynx

• a musculofascial half-cylinder that links oral
  nasal cavities in the head to the larynx
  esophagus in the neck.
• The pharyngeal cavity is a common pathway for air
  and 'food'.

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• pharynx is subdivided into three regions,
• nasopharynx,
• oropharynx,
• laryngopharynx

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Nasopharynx

• is behind the choanae of the nasal cavities and
  above the level of the soft palate.
• There is a large collection of lymphoid tissue
  (the pharyngeal tonsil) in the mucosa covering
  the roof of the nasopharynx.
• Enlargement of this tonsil, known then as
  adenoids, can occlude the nasopharynx so that
  breathing is only possible through the oral
  cavity
• in the pharynx that the air and food pathways
• the soft palate serves as a flap-valve which
  shuts off the mouth from the oropharynx

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The larynx

• hollow musculoligamentous structure with a
  cartilaginous framework that caps the lower
  respiratory tract.
• The cavity is continuous below with the trachea,
  above opens into pharynx immediately posterior
  inferior to the tongue

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• The larynx is both a valve (or sphincter) to
  close the lower respiratory tract, and an
  instrument to produce sound.
• It is composed of
• 3 large unpaired cartilages (cricoid, thyroid,
  and epiglottis).
• 3 pairs of smaller paied cartilages (arytenoid,
  corniculate, and cuneiform).
• a fibroelastic membrane and numerous intrinsic
  muscles.

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The thyroid cartilage

• the largest one
• formed by right left lamina, which are widely
  separated posteriorly, but converge and join
  anteriorly.
• They meet at laryngeal prominence ('Adam's
  apple').
• more apparent in men than women.

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The cricoid cartilage

• most inferior one
• completely encircles the airway
• It is shaped like a 'signet ring'
• Landmark for tracheostomy.

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The cricoid cartilage

• has two articular facets on each side for
  articulation with other laryngeal cartilages.
• one facet posteriorly articulation with arytenoid
  cartilage
• Lateraly facet articulation with the thyroid
  cartilage.

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Epiglottis

• a 'leaf-shaped' cartilage attached to the thyroid
  cartilage.
• The upper margin of the epiglottis is behind the
  pharyngeal part of the tongue.
• The sides are attached to the arytenoid
  cartilages by aryepiglottic folds

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Arytenoid cartilages

• are pyramid-shaped cartilages with three
  surfaces, a base of arytenoid cartilage, an apex
  of arytenoid cartilage, vocal process, and
  muscular process
• Articulate with cricoid cartilage

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• Corniculate articulate with arytenoid cartilages
  attach to aryepiglottic folds
• Cuneiform found the fold to give strength to it

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• The ligaments of the Larynx

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Thyrohyoid membrane

• Connect thyroid cartilages with hyoid bone.
• Opening on in the lateral part of on each side
  for superior laryngeal arteries, nerves,
• Posteriorly thickened lateral thyrohyoid
  ligaments.
• thickened anteriorly form the median thyrohyoid
  ligament.
• Cricotracheal ligament connect cricoid to 1st
  ring to trachea

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Quadrangular membrane

• extends between epiglottis arytenoid cartilages
  
• its inferior margin forms the vestibular ligament
  covered by vestibular fold (false vocal cord)

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Cricothyroid ligament

• its lower margin is attached to cricoid cartilage
  
• Extend superiorly as a free margin within the
  thyroid cartilage
• It forms the important vocal ligament on each
  side.
• This ligament is covered by vocal folds (true
  vocal cords)
• The anterior end of each vocal ligament is
  attached to the thyroid cartilage, and the
  posterior end is attached to vocal process of the
  arytenoid cartilage.

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Division into three major regions

• Two pairs of mucosal folds, the vestibular (pink)
  and vocal folds (white), which project medially
  from the lateral walls of the laryngeal cavity
  constrict it and divide it into three major
  regions
• the vestibule,
• a middle chamber
• the infraglottic cavity

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Inlet of the Larynx

• opening is wider in front than behind
• Bounded by
• in front by epiglottis
• laterally by the aryepiglottic fold
• posteriorly by arytenoid, corniculate and
  cuneiform cartilages.

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The Piriform Fossa

• is a recess on either side of the fold inlet
• It is bounded medially by aryepiglottic fold
  laterally by thyroid cartilage thyrohyoid
  membrane

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laryngoscope

• 2 triangularshaped opening
• rima vestibuli between two adjacent vestibular
  folds
• rima glottidis between the two adjacent vocal
  folds).

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muscles of the larynx

• cricothyroid muscles
• Vocalis
• Posterior cricoarytenoid
• Lateral cricoarytenoid
• Transverse arytenoid
• Thyro-arytenoid
• Oblique arytenoid

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Actions on the vocal folds
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LARYNGEAL MUSCLES
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Cricothyroid muscles

• The fan-shaped cricothyroid muscles
• arch of the cricoid cartilage to the thyroid
  cartilage
• External branch of superior laryngeal nerve from
  the vagus nerve X
• Stretch the vocal cords

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Thyro-arytenoid muscle

• Posterior cricoarytenoid
• Lateral cricoarytenoid
• Transverse arytenoid
• Oblique arytenoid
• Thyro-arytenoid
• Vocalis

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Nerves

• Sensory Nerves
• Above the vocal cords internal laryngeal branch
  of the superior laryngeal branch of the vagus
• ?Below level of the vocal cords The recurrent
  laryngeal nerve

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Motor Nerves

• All the intrinsic muscles of the larynx except
  the cricothyroid muscle are supplied by the
  recurrent laryngeal nerve.
• The cricothyroid muscle is supplied by external
  laryngeal branch of the superior laryngeal branch
  of the vagus.

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Superior laryngeal nerves

• The superior laryngeal nerves originate from the
  inferior vagal ganglia
• descend and divide into internal and external
  branches just above the level of the superior
  horn of the hyoid bone
• the external branch (external laryngeal nerve)
  supplying the cricothyroid muscle
• the internal branch (internal laryngeal nerve)
  penetrate the thyrohyoid membrane it is mainly
  sensory and supplies the laryngeal cavity down to
  the level of the vocal folds.

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The recurrent laryngeal nerve

• sensation to the inferior half of the larynx
• Motor to intrinsic laryngeal musculature. (not CT)

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BLOOD SUPPLY

• The superior laryngeal artery is a branch of the
  superior thyroid artery, derived from the
  external carotid artery
• The inferior laryngeal artery derived from the
  inferior thyroid artery, which originates from
  the thyrocervical trunk of the subclavian artery.