Anatomy of the Larynx

Question 1

3 main functions of larynx?

Answer 1

voice stimulation
sphincter of respiratory tract
- regulates airflow
- protection of aspirated objects
conduit for air

Question 2

what does the larynx consist of?

Answer 2

series of cartilages joined by connective tissue and moved by muscle
located between the pharynx and trachea

Question 3

where is the larynx located?

Answer 3

in the visceral layer of the pretracheal fascia of the neck

Question 4

what is enclosed in the pretracheal fascia?

Answer 4

strap muscles
thyroid gland
trachea and larynx
oesophagus and pharynx
recurrent laryngeal nerves

Question 5

what are the strap muscles?

Answer 5

very thing muscular layer which lies anteriorly to the visceral layer of the pretracheal fascia
function as accessory muscles of breathing

Question 6

4 layers of fascia in the neck?

Answer 6

investing fascia = encloses everything
prevertebral fascia = surrounds vertebrae and paravertebral muscles
carotid sheaths = surrounds carotid arteries and veins either side of midline
pretracheal fascia = surrounds midline structres

Question 7

what structures lie around the larynx?

Answer 7

anterior to the laryngopharynx
between the carotid sheath structures
between C4 and C6 vertebrae

Question 8

at what level is the hyoid bone found?

Answer 8

C3

Question 9

cricoid cartilage is found at what level?

Answer 9

C6

also beginning of oesophagus

Question 10

at what level is the top of the thyroid palpated?

Answer 10

C4/5

Question 11

how is the larynx involved in aspiration?

Answer 11

raising of the larynx towards the oesophagus reduces the chance of aspiration
if aspiration does occur, then the cough reflex engages

Question 12

what is the function of cartilage in the upper resp tract?

Answer 12

maintains patency

allows movement

Question 13

what does the larynx consist of?

Answer 13

skeleton of cartilages suspended from hyoid bone

Question 14

3 functions of larynx?

Answer 14

maintains patency
cartilage prevents entry of foreign body
vocal cords and cough reflex
produces sound

Question 15

features of laryngeal cartilages?

Answer 15

diagram

Question 16

only 1 area of cartilage in the larynx/trachea is a complete ring, what is this?

Answer 16

cricoid cartilage

Question 17

2 main joints in the movement of the larynx?

Answer 17

cricothyroid joint

cricoarytenoid joint

Question 18

the epiglottis is what type of cartilage and why?

Answer 18

elastic

moves down to cover larynx to allow food to pass into the oesophagus

Question 19

4 important cartilages in the larynx?

Answer 19

epiglottis
thyroid
arytenoid
cricoid

Question 20

how can cricoid pressure be used?

Answer 20

allows blockage of oesophagus in emergency situation to prevent aspiration of gastric contents
press in the cricoid cartilage
lamina of the cricoid cartilage compresses the oesophagus by pressing it against C6 vertebra
oesophagus is closed by the airway is open so ventilation is uninhibited

Question 21

features of larynx?

Answer 21

laryngeal vestibule = most superior
false vocal cord (vestibular fold)
laryngeal ventricle
true vocal fold
infra-glottic cavity

Question 22

what are vocal cords and what 2 pairs are present in the larynx?

Answer 22

free borders of mucosa covered connective tissue in the larynx
true vocal cords
- vocal process of arytenoid cartilage to thyroid cartilage, movement impacts sound
false vocal cords
- arytenoid cartilage to epiglottis

Question 23

during laryngoscopy, where is the laryngoscope inserted?

Answer 23

into the vallecula (space between epiglottis and tongue)

Question 24

what is seen on laryngoscopy?

Answer 24

epiglottis
outer line = false vocal cord
inner line = true vocal cord
space between right/left vocal cords = rima glottidis

Question 25

what is the aryepiglottic fold?

Answer 25

superior border of quadrangular membrane

Question 26

what type of muscle are the intrinsic muscles of the larynx and what do they do?

Answer 26

skeletal muscle
cause movement of vocal cords
- tension = increased pitch
- relaxation = decreased pitch
- adduction = quieter
- abduction = louder

Question 27

what nerve innervates intrinsic muscles of the larynx?

Answer 27

CN X (vagus)

Question 28

which intrinsic larynx muscles are tensors and what do they do?

Answer 28

cricothyroid muscles

• tense vocal ligament causing increased pitch
• nods thyroid cartilage
• attaches between anterolateral cricoid cartilage to inferior horn of thyroid cartilage

Question 29

what are the relaxor muscles of the larynx?

Answer 29

thyroarytenoid muscles

• relax vocal ligament decreasing the pitch
• attaches between posterior thyroid and anterior arytenoid cartilage

Question 30

what are the first adductor muscles of the larynx and what do they do?

Answer 30

lateral crico-arytenoid muscles

• adduct/bring vocal ligaments together making voice quieter
• attaches between muscular process of arytenoid to anterior cricoid cartilage

Question 31

what are the second adductor muscles of the larynx and what do they do?

Answer 31

arytenoid muscles

• adducts/brings vocal ligaments together making voice quieter by closing rima glottidis
• attaches between arytenoid cartilages

Question 32

what are the abductor muscles of the larynx and what do they do?

Answer 32

posterior crico-arytenoid muscles

• abducts vocal cords making voice louder by opening rima glottides
• attaches between posterior cricoid cartilage to muscular process of arytenoid cartilage

Question 33

how does shape of rima glottides relate to type of speech?

Answer 33

laryngeal muscles relaxed = slightly open = normal respiration
contraction of posterior crico-arytenoids = wide open = forced respiration
contraction of arytenoids = completely closed = phonation
contraction of lateral crico-arytenoids = slightly open only at posterior end = whispering

Question 34

how may a supra-glottides tumour spread?

Answer 34

drain to superior deep cervical nodes

Question 35

how may glottic tumours spread?

Answer 35

present on the cords
95% stay on the cords
presents with voice change/airway obstruction

Question 36

how may a sub-glottic tumour spread?

Answer 36

spread to paratracheal nodes

presents with voice/airway obstruction

Question 37

how does controlled expiration occur?

Answer 37

contraction of anterolateral abdominal wall and inspiratory intercostal muscles
this helps build pressure in the respiratory tree inferior to the larynx (subglottal pressure)
pressure required depends on vocal task

Question 38

how does phonation (speech) occur?

Answer 38

once subglottal pressure threshold is reached then air crosses vocal cords causing vibration
length/tension of vocal cords dictates pitch of sound produced by vibration of cords
degree of opening and the shape of the rima glottides also important

Question 39

what gives resonance to the voice?

Answer 39

larynx is insufficient to produce loud sound
laryngeal buzz is amplified by the pharynx, oral and nasal cavities
funnel shaped pathway from larynx to mouth

Question 40

how are oral sounds produced?

Answer 40

soft palate tenses (CN V3) and elevates (CN X) to close off entrance into nasopharynx
directs stream of air through the oral cavity
sound is interrupted by the tongue (CN XII) and the teeth/lips (CN VII) to produce most vowels and consonants in English language

Question 41

how are nasal sounds produced?

Answer 41

soft palate tenses (CN V3) and descends (CN X) to close off entrance into oropharynx
directs stream of air through nasal cavity
produces one of three sounds “m”, “n”, or “ing” depending on position of tonge (CN XII), teeth and lips (CN VII)

Question 42

through what 3 alternative methods can speech be obtained if larynx is removed?

Answer 42

tracheo-oesophageal puncture
oesophageal speech (suck air into oesophagus and belching the sound)
electrolarynx

Question 43

what nerve innervates the intrinsic muscles of the larynx (apart from the cricothyroid muscles)

Answer 43

inferior laryngeal nerve

Question 44

what nerve innervates the cricothyroid muscle

Answer 44

external laryngeal nerve

Question 45

what innervates the mucosa of the larynx?

Answer 45

above the vocal folds = internal laryngeal nerve

below the folds = inferior laryngeal nerve

Question 46

where does the inferior laryngeal nerve arise?

Answer 46

left recurrent laryngeal nerve becomes the inferior laryngeal nerve at the level of the cricothyroid joint

Question 47

what is galen’s anastomosis?

Answer 47

anastomosis between internal and inferior laryngeal nerves

around level of thyroid cartilage