Pharynx & Larynx

• What does the frequency of the oscillating air also determine?

  The pitch, which varies to allow intonation & expression
• What happens after the vocal folds are adducted?

  - Pressure then builds up from below until it forces the folds apart, allowing the air to escape.

  - Cycle repeats & converts the air into a series of puffs at a frequency determined by the sub-glottal pressure & the mass and tension on the vocal ligaments
• How do the vocal folds help achieve phonation?

  They're adducted, obstructing air flow
• What does phonation consist of?

  Converting an even flow of expired air passing through the larynx into an oscillating flow with a frequency of 16-20,000 Hz (which is within range of human hearing)
• When does phonation normally take place?

  Normally during expiration. It's possible during inspiration but it's not efficient and can't be maintained for long
• what is phonation?

  producing sound
• Where does Sensory nerve supply to the larynx come from?

  via the internal laryngeal nerves from the mucous membrane above the vocal folds, and the recurrent laryngeal nerve from the area below the vocal folds
• What is the submucosal lymphatic plexus of the larynx drained by?

  Deep cervical lymph nodes

  
  

  - above the vocal folds lymph vessels pierce the thyrohyoid membrane to reach the upper deep cervical lymph nodes

  - below these join the lower deep cervical lymph nodes
• Where does motor nerve supply to the larynx come from?

  all of the intrinsic muscles of the larynx are supplied by the external laryngeal nerves, that targets the cricothyroid, and the recurrent laryngeal nerve that targets the remainder
• What is the larynx innervated by?

  Laryngeal nerves, branching from the vagus nerve
• What performs venous drainage in the larynx?

  Laryngeal veins, which will then drain onto superior & inferior thyroid veins
• Where does the blood supply to the larynx come from?

  Mainly by the superior thyroid artery & the inferior thyroid artery which then branch out to form Laryngeal arteries

  
• Where does the nerve supply to the larynx come from?

  - Superior laryngeal nerve for upper parts e.g. epiglottis & crichoid

  - Recurrent laryngeal nerve for lower parts
• What are the 3 separate functions of the intrinsic muscles of the larynx?


  1. Open the rima glottidis to allow the passage of air in and out

  2. Close the vestibule and rima during swallowing to prevent aspiration of food

  3. Control the tension in the vocal folds for phonation

  
• Why are intrinsic muscles (of the larynx) named as such?

  They are so called because they originate & insert into laryngeal cartilages e.g. cricothyroid

  
• Why are extrinsic muscles (of the larynx) named as such and where do they insert?


  Because they have a remote origin but they insert into the larynx or hyoid bone. These supra & infrahyoid muscles act to move the larynx up or down

  
• ligaments of the larynx.

  
  

  describe the Cricothyroid Membrane


  A fibroelastic sheet filling the space between the vocal folds and the cricoid cartilage (conus elasticus)
• ligaments of the larynx.

  
  

  describe the Quadrangular Membrane

  A thin fibroelastic sheet filling the space between the aryepiglottic ligament and ventricular ligament
• ligaments of the larynx.

  
  

  describe the aryepiglottic Ligaments

  These pass upwards from the apices of the arytenoid cartilages to the lateral border of the epiglottis
• ligaments of the larynx.

  
  

  describe the Ventricular Ligaments


  These two bands of fibres run from the lateral borders of the arytenoid cartilages to the internal lamina of the thyroid cartilage. These folds, which run above the vocal ligaments are also covered by mucous membrane and are the ventricular folds (false vocal folds)
• ligaments of the larynx.

  
  

  describe the Vocal ligaments

  These are thick bands of elastic fibres running from the vocal processes of the arytenoid to the thyroid cartilage and are covered by mucous membrane, the vocal folds
• ligaments of the larynx.

  
  

  describe the Thyrohyoid Membrane


  A fibroelastic sheet joining the inferior surface of the hyoid bone to the superior aspect of the thyroid cartilage. The lateral borders are free and thickened
• Name and describe all the different ligaments of the larynx.

  
• paired cartilages of the larynx:

  
  

  Where are the cuneiform cartilages located?

  Within the aryepiglottic folds

  
• paired cartilages of the larynx:

  
  

  Where do the corniculate cartilages sit?

  Atop the apices of the arytenoid cartilages, extending their length

  
• paired cartilages of the larynx:

  
  

  what are the corniculate cartilages?

  tiny elastic cartilages
• paired cartilages of the larynx:

  
  

  What does the arytenoid cartilage provide attachment for?

  The vocal process as well as several muscles
• paired cartilages of the larynx:

  
  

  Where are the arytenoid cartilages located?

  These 2 pyramid-shaped cartilages lie on the posterior lamina of the cricoid cartilage and articulate via a synovial joint

  
• unpaired cartilages of the larynx:

  
  

  how is the epiglottis positioned?

  The broad leaf is orientated upwards & backwards lying behind the hyoid bone and reaching to the posterior part of the tongue

  
• unpaired cartilages of the larynx:

  
  

  What is the epiglottis?

  A fibroelastic cartilage shaped like a leaf with the stem anchored into the angle of the thyroid laminae.

  
• unpaired cartilages of the larynx:

  
  

  What is the only cartilage to completely encircle the larynx?

  Cricoid cartilage
• unpaired cartilages of the larynx:

  
  

  What is the cricoid cartilage shaped like?

  A signet ring i.e. a thin band with a quadrilateral plate

  
• unpaired cartilages of the larynx:

  
  

  Where does the cricoid cartilage sit?

  Sits immediately below the thyroid cartilage at the level of C6 & faces posteriorly
• unpaired cartilages of the larynx:

  
  

  Describe the appearance of the thyroid cartilage.

  The largest & consists of 2 plates joined anteriorly in the midline. In males, the union gives an acute angle & the cartilage is usually a more prominent feature of the neck (Adam's apple). In females, the union is much more obtuse

  
• What are the walls of the larynx supported by?

  A series of cartilages------>

  
  

  3 large cartilages- thyroid, cricoid & epiglottis (unpaired)

  
  

  3 small paired cartilages- arytenoid, cuneiform & corniculate
• Where does the inlet (the entrance of the cavity of the larynx) lie?

  Immediately behind the posterior third of the tongue
• Where does the larynx extend from & go to?

  Base of tongue (C3) to the trachea (C6).
• Where does the larynx lie?

  Anterior to the laryngeal part of the pharynx

  
• What is the larynx?

  A complex unit responsible for voice production as well as an air passageway linking the pharynx with the trachea. It also acts as a sphincter to prevent food from entering the trachea

  
• Describe the lymphatic drainage of the pharynx.

  Lymph from this region drains mostly into the deep cervical nodes but some posterior ones enter the retropharyngeal nodes, which lie between the prevertebral & buccopharyngeal fascia