Anatomy of the Phonatory Stystem Flashcards
What is a Larynx?
- The larynx, is a funnel-shaped organ.
- It is located in the throat (pharynx)
It is formed by the hyoid bone and several cartilages, which are connected by muscles and ligaments
List examples of how the larynx is a valve
e.g. “fixing” or stabilizing thorax during weightlifting, giving birth, increasing intra-abdominal pressures to expel metabolic waste
Functions of the Larynx: Biological and Non Biological
Biological :
- Acts as a valve to prevent air from escaping the lungs
- Products from the intestinal tract.
- Prevents foreign substances from entering lungs, trachea and glottis
- Forcefully expels foreign substances which threaten the trachea
Non-Biological:
•The production of sound
Describe the Larynx
- Composed of a series of cartilages, one bone, numerous muscles, ligaments, joints, and all covered by mucous membrane
- Inside, above, and below the larynx are a series of cavities
- Sits atop the trachea and forms a “valve” that can close off the airway
- Immediately posterior to the larynx is opening to the esophagus
- Remember that the esophagus shares a wall with the trachea
Cartilaginous Structure of the Larynx
•Larynx is suspended by one bone and formed by five major cartilages (one is paired) and 3 paired minor cartilages.
LARYNGEAL CARTILAGES
- Thyroid
- Cricoid
- Arytenoids
- Epiglottis
- Corniculates
- Triticial (cartilago triticea)
- Cuneiforms (additional)
Thyroid Cartilage
- Largest, most prominent of the laryngeal cartilages
- Forms V-shaped laryngeal prominence (Adam’s apple) anteriorly
- Anterior end of each vocal fold forms an attachment to internal surface of thyroid cartilage at Adam’s apple
- 2 wings: upper horns & lower horns
Thyrpid cartilage position
- Attached to the hyoid bone by the thyrohyoid membrane
- Forms a joint with the cricoid cartilage: cricothyroid joint
- Rotation about the cricothyroid joint can change vocal fold length by 25%
Cricoid Cartilage
•Ring-shaped cartilage below thyroid cartilage and atop the trachea
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•2 concave facets for inferior horns of the thyroid cartilage (cricothyroid joint articular facets)
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•2 convex facets for the arytenoids (cricoarytenoid facets)
Cricoid Cartilage and Ligament
- Ligaments attach cricoid to thyroid superiorly, and 1st tracheal ring inferiorly
- Anterior attachment: cricothyroid ligament
Cricothyroid Joint Action and Effect on Vocal Fold Length
- Contraction of cricothyroid muscles slides thryoid cartilage anteriorly and rotates anterior thyroid toward the anterior cricoid.
- The result is lengthening of the vocal folds (TA muscles)
Cricothyroid Joint
- Cricoid and inferior cornu of the thyroid
- Permits rotation and gliding
- provides for major adjustment for change in vocal pitch
Arytenoid Cartilages
- 2 small, pyramidal-shaped cartilages articulate with cricoid cartilage posteriorly
- Processes include:
- Apex (top – corniculate cartilages sit here)
- Muscular process: attachment point for adductors/abductor
- Vocal process: attachment for vocal ligament/fold
CRICOARYTENOID
Cricoarytenoid joint = synovial (highly mobile)
- Rocking motion of the arytenoid on the cricoid
- Gliding motion
- Rotating motion
Cricoarytenoid Joint
- Cricoid and arytenoid
- Permits rocking and gliding and perhaps minimal rotation
- Allows the two vocal processes to move toward each other permitting adduction
- Facilitate changes in vocal fold length
Epiglottis Cartilage
- Leaf-shaped cartilage
- Anterior surface of epiglottis attached to body of hyoid bone via hyoepiglottic ligament
- Epiglottis pulls down and covers glottis during swallowing – part of the laryngeal valve
Hyoid Bone
- Only bone in the larynx: all other structural elements are cartilage
- “Floats” – no other bony attachment
- Attachment site for many muscles
- Components:
- Corpus (body),
- Greater Horn (cornu),
- Lesser Horn (cornu)
Extrinsic Muscles of the Larynx
- One attachment on cartilage and other on non laryngeal structures
- Makes major adjustments of the larynx such as elevation and depression
- Works with the tongue and important in swallowing
Extrinsic Muscles of the Larynx
Suprahyoid: above the hypoid
- Digastric
- Stylohyoid
- Mylohyoid
- Geniohyoid
Extrinsic Muscles of the Larynx
Infrahyoid: below the hyoid
- Sternothyroid
- Omohyoid
- Thyrohyoid
- Sternohyoid
Suprahyoid Muscles (above the hyoid): 1. Digastricus (ABD & PBD)
- Deep, two bellied structure composed of two muscles
- ABD - anterior belly digastric
- PBD - posterior belly digastric
- Joined end to end by intermediate tendon
Digastricus (ABD & PBD): Action
- Action: jaw opener (speech muscle) also can elevate hyoid bone
- ABD: elevates & moves hyoid forward
- PBD: elevates & moves hyoid backward; together they elevate the hyoid
Suprahyoid Muscles: 2. Mylohyoid (MH)
- Paired muscle that forms floor of the mouth
- Action: elevates floor of the mouth (affects tongue height), can elevate the hyoid bone
