SHS 300 - Phonatory System (Larynx)

biological functions of the larynx

• prevents air from escaping the lungs when valving is needed (valving = closing the vocal folds)

• prevents foreign substances from entering the lungs

• expels foreign substances that threaten the trachea (through coughing)

non-biological functions of the larynx

sound generation

cartilages that are important for voice production

thyroid, cricoid, and arytenoid

cartilage that is crucial for airway protection during swallowing

epiglottis

movement of the cricothyroid joints - how does this change the vocal folds?

movement: rotation

• thyroid cartilage moves forward and downward

• cricoid cartilage moves backward and upward

result: elongates the vocal folds which increases the pitch of the voice

movement of the cricoarytenoid joints - how does this change the vocal folds?

movement: rocking

• arytenoids move upward and outward (ABDUCTION - opening - of vocal folds)

• arytenoids move downward and inward (ADDUCTION - closing - of vocal folds)

result: abduction or adduction of the vocal folds

thyroid cartilage

cricoid cartilage

arytenoid cartilage

epiglottis cartilage

cuneiform cartilage

label red

corpus/body of hyoid bone

label green

greater horn of hyoid bone

label yellow

lesser horn of hyoid bone

label c

thyroid lamina

label e

angle of thyroid

label a

thyroid notch

label d

laryngeal prominence

label b

superior horn of thyroid cartilage

label f

inferior horn of thyroid cartilage

label g

thyroid facet

label a

anterior arch of cricoid

label b - where does it connect to?

inferior facet of cricoid; connects to thyroid cartilage

label c - where does it connect to?

superior facet of cricoid; connects to arytenoid cartilage

label d

cricoid lamina

label a

corniculate cartilage

label b

vocal process (towards the internal larynx cavity)

label c

muscular process (away from the internal larynx cavity)

label d

apex (top point; excludes corniculate cartilage)

label e - where does it connect to?

facets; connect to cricoid cartilage

label a

body of epiglottis

label b

lingual surface of epiglottis

label c

petiole (base of epiglottis)

label d

laryngeal surface of epiglottis

label b - is it extrinsic or intrinsic?

vocal ligament; intrinsic

label g - is it extrinsic or intrinsic?

quadrangular membrane; intrinsic

label f - is it extrinsic or intrinsic?

ventricular ligament (false VFs); intrinsic

label e - is it extrinsic or intrinsic?

conus elasticus; intrinsic

label d - is it extrinsic or intrinsic?

lateral cricothyroid ligament; intrinsic

label c - is it extrinsic or intrinsic?

medial cricothyroid ligament; intrinsic

label k - is it extrinsic or intrinsic?

lateral thyrohyoid ligament; extrinsic

label h - is it extrinsic or intrinsic?

thyrohyoid membrane; extrinsic

label i - is it extrinsic or intrinsic?

medial thyrohyoid ligament; extrinsic

label j - is it extrinsic or intrinsic?

cricotracheal ligament; extrinsic

label connection between epiglottis and hyoid bone - is it extrinsic or intrinsic?

hyoepiglottic ligament; extrinsic

label a

thyrohyoid

label b

sternothyroid

label a

digastric (anterior and posterior bellies)

label b

sternohyoid

label c

omohyoid

label d

mylohyoid

label a

thyroarytenoid

label b

lateral cricoarytenoid

label c

transverse arytenoid

label d

posterior cricoarytenoid

label e

oblique arytenoid

label f

cricothyroid

intrinsic vs extrinsic laryngeal muscles

extrinsic - one attachment to structures outside the larynx

intrinsic - both attachments are within the larynx

label a

thyromuscularis

label b

thyrovocalis

label c

vocal ligament

part that makes up the anterior 2/3rds of the vocal folds

membranous portion

part that makes up the posterior 1/3rd of the vocal folds

cartilaginous portion

muscle that rocks the arytenoid cartilages away from the midline (abduction)

posterior cricoarytenoid (function)

muscle that rocks the arytenoid cartilages toward the midline (adduction)

lateral cricoarytenoid (function)

muscles that pull the arytenoid cartilages toward each other to close the posterior glottis

interarytenoids (function)

thyroarytenoid - function and motor innervation; intrinsic or extrinsic?

function: decrease the distance between the thyroid and arytenoid cartilages, which will shorten the VFs and decrease the pitch of the voice (***secondary: adduction***)

motor innervation: CNX (vagus), recurrent laryngeal nerve

intrinsic or extrinsic: intrinsic

posterior cricoarytenoid - function and motor innervation; intrinsic or extrinsic?

function: rock the arytenoid cartilages upward and outward (abduction)

motor innervation: CNX (vagus), recurrent laryngeal nerve

intrinsic or extrinsic: intrinsic

lateral cricoarytenoid - function and motor innervation; intrinsic or extrinsic?

function: rock the arytenoid cartilages downward and inward (adduction of the membranous portion of the VFs)

motor innervation: CNX (vagus), recurrent laryngeal nerve

intrinsic or extrinsic: intrinsic

interarytenoids - function and motor innervation; intrinsic or extrinsic?

function: adduction of the cartilaginous portion of the VFs and approximation of the arytenoid cartilages

motor innervation: CNX (vagus), recurrent laryngeal nerve

intrinsic or extrinsic: intrinsic

cricothyroid - function and motor innervation; intrinsic or extrinsic?

function: increase the distance between the thyroid cartilage and the vocal process of the arytenoid cartilage, which will increase the pitch of the voice

motor innervation: CNX (vagus), superior laryngeal nerve

intrinsic or extrinsic: intrinsic

sternothyroid - function and motor innervation; intrinsic or extrinsic?

function: depress the larynx

motor innervation: CNXII (hypoglossal) via C1-C3

intrinsic or extrinsic: extrinsic

point of attachment: sternum

thyrohyoid - function and motor innervation; intrinsic or extrinsic?

function: elevate the larynx

motor innervation: CNXII (hypoglossal) via C1

intrinsic or extrinsic: extrinsic

sternohyoid - function and motor innervation; intrinsic or extrinsic?

function: depress the larynx (by depressing the hyoid bone)

motor innervation: CNXII (hypoglossal) via C1-C3

intrinsic or extrinsic: extrinsic

point of attachment: hyoid bone + sternum

omohyoid - function and motor innervation; intrinsic or extrinsic?

function: depress the larynx (by depressing the hyoid bone)

motor innervation: CNXII (hypoglossal) via C1-C3

intrinsic or extrinsic: extrinsic

point of attachment: shoulder

anterior belly of digastric - function and motor innervation; intrinsic or extrinsic?

function: moves the hyoid bone upward and forward

motor innervation: CNV (trigeminal)

intrinsic or extrinsic: extrinsic

point of attachment: mandible + intermediate tendon

posterior belly of digastric - function and motor innervation; intrinsic or extrinsic?

function: moves the hyoid bone upward and backward

motor innervation: CNVII (facial)

intrinsic or extrinsic: extrinsic

point of attachment: mastoid process

stylohyoid - function and motor innervation; intrinsic or extrinsic?

function: move the hyoid bone upward and backward

motor innervation: CNVII (facial)

intrinsic or extrinsic: extrinsic

point of attachment: styloid process

mylohyoid - function and motor innervation; intrinsic or extrinsic?

function: move the hyoid bone upward and forward

motor innervation: CNV (trigeminal)

intrinsic or extrinsic: extrinsic

point of attachment: mandible

geniohyoid - function and motor innervation; intrinsic or extrinsic?

function: move the hyoid bone upward and forward

motor innervation: CNXII (hypoglossal) via C1

intrinsic or extrinsic: extrinsic

cranial nerve that transmits sensory information from the laryngeal mucosa

CNX (vagus)

steps involved in the opening phase of the vibratory cycle

1. contraction of the lateral cricoarytenoid muscle = adduction of the VFs

2. build-up of subglottal pressure

3. opening force develops; when the force exceeds the resistance provided by the adducted VFs, the VFs will be forced apart in the vertical direction in a bottom-up fashion***

4. lateral excursion of VFs (VFs separate in the lateral direction in a bottom-up fashion)***

5. complete abduction of VFs; flow of air dissipates

***occurs simultaneously

steps involved in the closing phase of the vibratory cycle

1. elastic recoil of VFs will return them to the position of equilibrium, but not full adduction

2. inertia will keep the VFs moving closer together

3. aerodynamic forces + biomechanical properties

   1. Bernoulli effect

      1. constriction due to VF configuration will cause the air molecules to speed up

      2. as the air molecules speed up, the pressure will drop to keep the total energy constant

      3. a drop in pressure creates a suction force, which will bring the VFs together

   2. pressure differential due to VF configuration (divergent shape - bring VFs together)

convergent glottal configuration

• separation at the bottom of the VFs

• glottal pressure is high

• push VFs AWAY from the midline

divergent glottal configuration

• NO separation at the bottom of the VFs

• glottal pressure is low

• push VFs TOWARD the midline (“suction” force)

vertical phase - abduction and adduction

abduction - bottom-up

adduction - bottom-up

longitudinal phase - abduction and adduction

abduction - bottom-up

adduction - up-bottom (like a zipper)

glottic space/glottis

space between the true vocal folds

supraglottic space

above the vocal folds

laryngeal vestibule

cavity from the entrance of the larynx to the ventricular ligaments (false VFs)

laryngeal additus

opening to the larynx

subglottic space

below the vocal folds

laryngeal ventricle (and function)

space between the false and true VFs

contains mucous glands that secrete mucus to lubricate the true VF (smooths the contact between one VF and the other to prevent damage/lesions)

mucosa of VF - layers that make up it and function

squamous epithelium

superficial layer of lamina propria

function: the part that primarily vibrates

vocal ligament of VF - layers that make up it and function

intermediate layer of lamina propria

deep layer of lamina propria

function: provides structure

5 layers of VF

squamous epithelium - outer shape; most external

superficial layer of lamina propria

intermediate layer of lamina propria

deep layer of lamina propria

vocalis muscle - main body of VFs

***increase in pliability from internal to external layers (example: deep layer is less pliable than the superficial layer)

label a

supraglottic space (and laryngeal vestibule)

label b

quadrangular membrane (internal laryngeal view)

label c

ventricular ligament (internal laryngeal view)

label d

vocal ligament (internal laryngeal view)