SLHS 303 - Exam 4

what is the larynx?

cartilaginous structure that serves as an organ for sound production; provides passage for air; protects the airway; phonation or voice production

what view of the larnyx?

frontal (ventral) view

A

epiglottis

B

hyoid bone

C

thyroid cartilage

D

cricoid cartilage

where is the larnyx located?

below the hyoid bone and above the trachea

what is the frame of the larynx made of?

cartilage

what is the interior of the larynx made of?

soft tissue (epithelium)

true vocal folds

soft (bilateral) folds of tissue located inside the larynx that are involved in airway protection and vibration (osscilation) for speech production; aka vocal folds

false vocal folds

bilateral fatty tissue located inside the larynx and above the true vocal folds that do not vibrate during speech

what are the true vocal fold configurations?

open (abduction) and closed (adduction)

open

abduction

closed

adduction

when are the vocal folds abducted?

during respiration

when are vocal folds adducted?

to protect airway from food and water or during heavy lifting

hyoid bone

the superior border or the larynx; suspended in the neck and held in place with muscles; consists of a body, greater cornu (horn) and lesser cornu; horseshoe-shaped

trachea

inferior border of the larynx; cartilaginous structure made of c-shaped rings; anterior to the esophagus

laryngeal cartilages

9 principle cartilages of the larynx; 3 single (epiglottis, thyroid, cricoid) and 3 paired (arytenoid, cuneiform, corniculate)

epiglottis

single cartilage that is thin and leaf-shaped; anterior to the laryngeal inlet (opening of the larynx); attached to the thyroid cartilage via the thyroepiglottic ligament and attached to the hyoid bone via the hyoepiglottic ligament

thyroid cartilage

single cartilage; largest of the laryngeal cartilage; attached to the hyoid bone by the thyrohyid membrane

cricoid cartilage

single cartilage that is shaped like a signet ring; attached to the trachea via cricotracheal ligament

A

lesser cornu

B

greater cornu (horn)

C

body

what part of the larnyx is this?

hyoid bone

what is this?

the first tracheal ring

what is this?

epiglottis

A

epiglottis

B

hyoid

C

hyoepiglottic ligament

D

thyroepiglottic ligament

what is this?

thyroid cartilage

A

superior horn

B

laryngeal prominence

C

thyroid lamina

D

inferior horn

A

hyoid bone

B

thyrohyoid membrane

C

thyroid cartilage

A

cricoid lamina

B

cricoid arch

C

Inferior horn of thyroid attaches here to form cricothyroid joint

A

thyroid cartilage

B

cricoid cartilage

C

tracheal cartilage

single (unpaired) cartilages

epiglottis, thyroid, cricoid

paired carilages

arytenoid, cuneiform, corniculate

arytenoid cartilages

paired, shaped like pyramids; features include apex, base and 2 processes (vocal and muscular)

corniculate cartilages

located at apex of arytenoid cartilages; described as cone-shaped; function: structural support

cuneiform cartilages

smallest laryngeal cartilage; found lateral to the corniculate cartilages; function: unknown, likely also provide structural support

cricothyroid

joint between cricoid and thyroid cartilages; the inferior thyroid horns articulate with facets on the cricoid arch; cricothyroid ligament holds the joint together

cricoarytenoid

joint between cricoid and arytenoid cartilages; the base of the arytenoids articulate with facets on the cricoid lamina; cricoarytenoid ligament holds the joint together

what cartilage is this?

arytenoid cartilages

A

apex of arytenoid cartilage

B

muscular process

C

base of arytenoid cartilage

A

cuneiform cartilage

B

corniculate cartilage

C

arytenoid cartilage

A

inferior horn of thyroid cartilage

B

cricothyroid ligament at the cricothyroid joint

C

cricoid cartilage

D

cricotracheal ligament

A

arytenoid cartilage

B

cricoarytenoid ligament

C

cricoid cartilage

innervation

nerve supply

laryngeal innervation

Cranial Nerve X (Vagus)

where are the cell bodies for motor neurons of the Vagus located?

in the nucleus ambigous

what two branches of the Vagus are important to vocal fold physiology

superior laryngeal nerve and recurrent laryngeal nerve

external branch of superior laryngeal nerve

motor branch that innervates the cricothyroid muscle; when the muscle contracts, the vocal fold gets tense and pitch increases

internal branch of superior laryngeal nerve

sensory branch brings back sensations from the area rostral to the true vocal folds

recurrent laryngeal nerve

provides both motor and sensory innervation to the larynx; sensory information from region below the true vocal folds; motor branch innervates all intrinsic muscles (except the cricothyroid); longer on the left side of the body

other cranial nerves that innervate muscles of the larnyx

CN V (trigeminal), CN VII (facial), CN XII (hypoglossal)

extrinsic laryngeal muscles

muscles which have one point of attachment in the larynx and the other outside of the larynx; work to move larynx up or down

suprahyoid muscles

move the larynx up (elevators)

infrahyoid muscles

move the larynx down (depressors)

suprahyoid muscles

aka laryngeal elevators; above the hyoid bone; important role in swallowing; may help with increasing singing pitch, but role not understood completely

digastric muscle

two bellies: anterior digastric and posterior digastric

anterior digastric

origin: mandible (jaw bone); insertion: hyoid bone; innervation: CN V

posterior digastric

origin: mastoid process on temporal bone; insertion: hyoid bone; innervation: CN 7

functions of digastric muscle

elevate hyoid bone (and larynx) (both bellies) & move hyoid bone (and larynx) forward (anterior belly)

stylohyoid muscle

origin: styloid process of temporal bone; insertion: body of hyoid bone; innervation: CN 7

stylohyoid muscle function

elevates and retracts the hyoid bone (and larynx)

mylohyoid muscle

a thin sheet of muscle which forms the floor of the mouth; origin: inside edges or the mandible; insertion: midline raphe, hyoid bone, and tongue; innervation: CN V

function of mylohyoid muscle

moves hyoid bone (and larynx) anterosuperiorly

geniohyoid muscle

located superior to the mylohyoid (closer to tongue); origin: center of mandible, insertion: hyoid bone; innervation: CN I

geniohyoid muscle function

moves hyoid bone (and larynx) anterosuperiorly

A

mandible (jaw bone)

B

anterior digastric belly

C

posterior digastric belly

A

stylohyoid muscle

B

body of hyoid bone

C

larynx

A

mylohyoid muscle

B

mandible

C

midline raphe

D

hyoid bone

A

geniohyoid muscle