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A&P Chapter 4

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Leia Neft

on 25 October 2017

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Transcript of A&P Chapter 4

Thyroid cartilage

Supra-and infrahyoid muscles
Raise and lower larynx
Change length of vocal folds
Intrinsic laryngeal muscles
Responsible for fine adjustments associated with
control of phonation

The Larynx
Suspended for a broad string of muscles
Muscles work together
Muscles achieve complex motions required for speech and non-

Interaction of Musculature

Intrinsic laryngeal muscles (cont’d)
Major types of Intrinsic muscles
Auxillary musculature

Intrinsic laryngeal muscles
Muscles that have both origin and insertion on
laryngeal cartilages
Innervation is by vagus nerve
Vagus nerve responsible for sensation and motor
function in the thorax, neck, and abdomen

Muscles of the Larynx

Larynx is surgically removed
Voicing source for speech is lost
Difficult to expectorate phlegm


First locate the Adam’s apple or thyroid
Place index finger on the notch
Use thumb and second finger on either side
Bring index finger slightly down
Feel the prominent thyroid angle

Palpation of the Larynx

Comprised of three unpaired cartilages
Cricoid cartilage
Thyroid cartilage
Epiglottis cartilage
Refer to Figure 4-1: Various views and
components of the larynx.

Other structures:
Hyoid bone

Average length of larynx
Adult males: 44 mm
Adult females: 36 mm

Musculo-cartilaginous structure
Located at the top of the last ring of the
Adjacent to cervical vertebrae 4 through 6

Structure of the Larynx

Produces phonation
Clamps airway in response to possible
intrusion by foreign objects
Food or liquids
Rapidly expels foreign matter away from
opening of airway

Biological Functions of Larynx

Source of voice for speech
Respiration provides energy that allows phonaiton


Also known as voicing
phonation is the voice for speech.
Product of vibrating vocal folds
Occurs within the larynx


Anatomy of Phonation

Chapter 4

Make a model larynx
Vocal folds
False vocal folds
intrinsic muscles
Larynx Project

Sits atop the arytenoids

Corniculate cartilages

Cricoid Cartilage

Elevation of the tongue
Elevates the larynx
Increases the tension of the cricothyroid
Keeps articulatory system from driving phonatory

Interaction of Musculature (Cont’d)

Laryngeal muscular system works as a
Laryngeal elevation
Laryngeal depression
Counters laryngeal elevation with controlled antagonistic

Extrinsic laryngeal muscles (cont’d)
Major types of Extrinsic muscles
Hyoid elevators
Laryngeal elevators
Hyoid depressors
Taryngeak depressors

Muscles of the Larynx (Cont’d)

Extrinsic laryngeal muscles
Muscles that have one attachment on a
nonlaryngeal structure
Elevate or depress the larynx
Make fine adjustments in the vocal mechanism
Important in swallowing

Muscles of the Larynx (Cont’d)

Intrinsic laryngeal muscles (cont’d)
Major functions
Open the vocal folds
Close the vocal folds
Tense the vocal folds
Relax the vocal folds

Cessation of activities such as swimming
Patient undergoes a tracheostomy
(removal of trachea)
Must breathe through a tracheostoma

Bring finger up to the top of the thyroid
Feel the corpus of the hyoid bone
Feel articulation of the hyoid and thyroid
Feel the lower margin of the thyroid
Place thumb at junction of thyroid and cricoid
Palpate the entire larynx

Vocal folds permit a person to hold their
Plays role in swimming
Assists in lifting
Important in childbirth
Plays role in defecation

Biologic Functions of Larynx (Cont’d)

Sensitive to external environment
Cigarette smoke and other pollutants
Sensitive to internal environment
Dry tissue harmful to vocal folds
Causes contact ulcers and vocal nodules
Therapy involves humidification, fluids, and

Vocal Fold Treatment

Area below vocal folds

Five layers of tissue
Space between the folds
Most important laryngeal space for speech
Defined by the variable sphincter that allows

Vocal Folds

Uses voiceless and voiced sounds
Voiceless sounds
Produced without use of vocal folds
Voiced sounds
Produced by action of vocal folds

Spoken Communication

Hyoid Bone

Arytenoid cartilages

Composed of three paired cartilages
Arytenoid cartilage
Corniculate cartilage
Cuneiform cartilage

Structure of the Larynx (Cont’d)

Embedded within the aryepiglottic folds

Cuniform cartilages

Is an extension of the trachea; also known as the voice box
Function: To protect the lungs
Secondary function: Phonation
Rests just avove the trachea in the front (anterior) portion of the neck
Is a muscular, membranous, and cartilaginous structure
Is suspended by muscles and ligaments attached to a V-shaped bone called the hyoid bone

A small flap of tissue that covers the entrance to the larynx
It automatically closes when swallowing, thus preventing food and drink from entering the airways
Vocal Folds:

A pair of thin muscles in the larynx
The vibrations of the vocal folds are the sources of voice
Muscles that separate
Vocal folds are open
There IS speech
With the vocal folds in an abducted position, the air supplied by the respiratory mechanism travel past the level of the vocal folds in an unvibrated manner
This is essential for the production of unvoiced consonants
Muscles that move inward
Vocal folds are closed
There is NO speech
When the vocal folds are closed (adducted), the flow of air supplied by the respiratory mechanism is stopped
Adductors (close the vocal folds)
Lateral cricoarytenoid - rock arytenoid in and down
Transverse arytenoid- medial compression to close vocal folds
Oblique arytenoid - adductor, medial compression
Abductors (open the vocal folds)
Posterior cricoarytenoid - only abductor of vocal folds
Cricothyroid - pars recta and pars oblique - 2 heads
Thyrovocalis - medial muscle of vocal folds

Intrinsic laryngeal muscles
Thyromuscularis - muscle mass lateral to thyrovocalis- muscular portion of vocal folds
Auxillary musculature
Thyroepliglottic – dilates the laryngeal opening
Superior thyroartyenoid
Aryepiglottic muscle - deflects epiglottis over airway opening to help protect the airway during swallowing

Hyoid and laryngeal elevators
Digastricus anterior and posterior (two muscle bellies)- anterior pulls hyoid up and forward, posterior up and back
Stylohyoid- elevate and retracts hyoid bone
Mylohyoid- floor of the oral cavity
Geniohyoid- elevate and draw hyoid forward
Genioglossus- tongue muscle and hyoid elevator
Hyoglossus- also lingual depressor
Thyropharyngeus- part of inferior pharyngeal constrictor- elevates larynx

Hyoid and laryngeal depressors
Sternohyoid - depresses hyoid or if suprahyoid muscles are contracted, fixes the hyoid & larynx
Omohyoid – two bellies - inferior and superior- depresses hyoid bone and larynx
Sternothyroid - depresses thyroid cartilage
Thyrohyoid - depresses hyoid or raises larynx
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