Functional Anatomy Of The Larynx

Question 1

What are the functions of the larynx?

Answer 1

Airway protection preventing food/fluid

Ventilation (movement of air etc entering airways into/out of lungs)

Important role in cough reflex rapidly expel anything inadvertently entering airway

Role in production of - sound (phonation)

Question 2

What is the larynx and where is it located

Answer 2

• ‘Tube’ created by series of ligaments/membranes, cartilages and muscles
• Lies below the hyoid bone - Hangs down behind hypoxic Bon e- attached behind membrane
• Part of the respiratory system (transmits air into/out of lower resp tract)
– Begins at laryngeal inlet
– Continues as the trachea (at C6/lower border of cricoid cartilage)

Question 3

What is the path of food and the path of inspired air

Answer 3

Inspired air via oral cavity/or nasopharynx  oropharynx  larynx  trachea
BUT
Food via oral cavity  oropharynx  laryngopharynx  oesophagus

Oropharynx is shared by food fluids dn air - only air should go into larynx

Question 4

What are the cartilages of the larynx

Answer 4

• Three single cartilages
• Thyroid, cricoid and epiglottis
• Three paired cartilages
• Arytenoid cartilages
 • Corniculate cartilage 
• Cuneiform cartilage
Last 2 unimportant

Thyroid cartilage has superior and inferior horn. Prominence at the root is aaalaryngeal prominence - “Adams apple”
Cricoid cartilage underdeath. The only cartilage in the resp tract that is a complete ring. Wider at the back.
The is a joint where thyroid sits on top of cricoid - allows for movement of thyroid cartilage on top of cricoid
Sitting at the back on top of cricoid - arytenoid cartilages

• Numerous membranes and ligaments connecting cartilages (and to hyoid), help give shape to the larynx

Question 5

What are teh membranes land ligamentsl

Answer 5

Ss
Numerous membranes and ligaments connecting cartilages (and to hyoid), help
give shape to the larynx
• Thyrohyoid membrane • Cricothyroid membrane • Cricotracheal membrane • Quandrangular membrane

Question 6

What is a cricothyroidotomy

Answer 6

Ss

Question 7

What is the quadrangular membrane and aryepiglotic folds

Answer 7

Attactches edges of epiglottis to arytenoid cartilage 
Aryepiglottic folds (2) Form margins Tracheal rings of oval inlet of the larynx

Question 8

What are the vestibule ligament and vocal ligament

Answer 8

Free lower border of quadrangular membrane forms vestibular ligament (false vocal cords)
Upper free border of cricothyroid ligament-thickened edge forming the vocal ligament

Question 9

What are the 3 parts of teh larynx

Answer 9

Mucosal folds divide larynx into 3 regions Supraglottis - top - up to and including false vocal cords - laryngeal vestibule
Glottis - where vocal folds are 0 narrowest part
Infraglottis (below)

Between vestibular and vocal folds is a small recess which leads laterally and upwards into the saccule (or sinus); contains mucous glands that keep vocal folds moist

Question 10

What is intubation

Answer 10

View vocal cords to allow for intubation: placement of a tube into subglottic region (i.e. below vocal cords)

Question 11

What is felxible nasoendoscopy

Answer 11

Flexible nasoendoscopy: insert flexible endoscope via nasal cavity and pharynx to then visualise larynx

Question 12

Whar are the fucntions of the laryngeal muscles

Answer 12

• Broadly have two main actions
– Alter the size and shape of the inlet
– Alter size/position of vocal cords
• Close the laryngeal inlet and vocal cords during swallowing, protecting respiratory tract
• Open vocal cords and allow movement of air during inspiration and expiration
• But also use movements of vocal cords in phonation and in cough reflex
• Glottis is narrowest part of larynx
• Position of arytenoids on cricoid cartilage determine position of true vocal cords and therefore size of aperture (rima glottidis/glottis)
• Intrinsic muscles play key role in the movement of vocal cords

Question 13

What is the only muscle to open the vocal cords (abduct)

Answer 13

Posterior cricoaryteoid

Question 14

Which nevre supplies the msucles of the larynx

Answer 14

• All supplied by recurrent laryngeal nerve of
vagus (CN X)
– Except cricothyroid muscle (external branch of
superior laryngeal nerve)

Question 15

When are vocal cordss adducted and abduct

Answer 15

• During inspiration and expiration the vocal cords aBduct
– Glottis wide open (vocal cords abduct to greater extent during deep breathing
• During phonation vocal cords aDduct
– Expired air is forced through closely adducted vocal cords to vibrate a column of air
• During a cough (explosion of compressed air) vocal cords powerfully aDducted, intrathoracic pressure builds, then cords suddenly aBducted

Question 16

What alters the pitch of vocal sound

Answer 16

• Pitch of vocal sound can be altered by tension and length of
vocal folds
– High-pitched sounds  vocal folds taut – Low-pitched sounds  folds are relaxed

Question 17

What does the cricothryoud muscle do and what is its innervation

Answer 17

• Bilateral contraction of cricothyroid muscle increases length and tension in vocal folds
– Only intrinsic muscle of larynx found on outside of larynx
– Innervated by external branch of superior laryngeal nerve (branch of CN X)

Cricothyroid muscle is innervated by external laryngeal nerve (external branch of superior laryngeal nerve)
Injury to nerve (closely related to superior thyroid artery) leads to hoarseness of voice especially when attempting higher pitched sounds

Question 18

What does the larynx do when swallowing

Answer 18

• Most important function of larynx is to protect airways from food/fluid during swallowing
• Contraction of aryepiglottic muscles acts to narrow laryngeal inlet and pull down epiglottis
• Assisted by elevation of larynx (pharyngeal muscles & supra hyoid muscles pull larynx up and forward)
• Closure of vocal cords (glottis)

• Suprahyoids and longitudinal pharyngeal muscles play an important role
• Act to elevate and anteriorly displace the larynx
• Helps ensure patency of pharynx so
food/fluid can be directed into it

Question 19

What is the nevre supply to the larynx

Answer 19

• Superior laryngeal nerve is a branch of the vagus
• Gives rise to internal and external branch
• Internal: purely sensory (above vocal
cords)
• External branch: motor to cricothyroid

Question 20

What is teh route o the RLN and what does it innervate

Answer 20

• Recurrent laryngeal nerve arises distally from vagus, then loops under right SCA and on left, the arch or aorta
• Ascends in tracheo-oesophageal groove
• Close anatomical relationship with thyroid gland and inferior thyroid arteries supplying the gland
• Innervates all intrinsic muscles of larynx (except cricothyroid)
• And provides sensory below vocal cords (infraglottic region)

Question 21

What are teh anatomical relations of the RLN

Answer 21

• Recurrent laryngeal nerves is close relation of inferior thyroid artery
– Potentially injured during thyroid surgery
• Other anatomical relations associated with RLN during its journey (on left and
right side)
– Aortic arch aneurysm (left RLN)
– Cancer involving apex of lung (right RLN)
– Disease or surgery involving larynx, oesophagus or thyroid
• RLN supplies intrinsic muscles of larynx responsible for vocal cord movements

Question 22

Describe unilateral vocal cord palsies

Answer 22

• Paralysed vocal cord assumes a paramedian position
– Between fully abducted and fully adducted
• Unilateral palsy may lead to hoarseness of voice +/-
ineffective cough
– Often contralateral side compensates in time (crosses midline to meet vocal cord on affected side)

Paralysed - somewhere between adduct or abduct.
Overtime, unaffected cords can overcompensate and come across the midlife
Cough will be effect. But no significant impact on breathing a

Question 23

Describe bilateral vocal cord palsies

Answer 23

• Bilateral lesions
– Both vocal cords paralysed and in paramedian postion
– Narrow glottis
– Significant airway obstruction…emergency surgical airway

Breathing effected. Bc narrow rema. Cant speak, cant cough.

Question 24

Whar are conditions ffected the larynx

Answer 24

• Laryngitis (inflammation of the vocal cords)
• Larnyngeal nodules
• Laryngeal cancer Laryngeal cancer
• Croup (read more)
• Epiglottitis (read more)
• Laryngeal oedema e.g. allergic reaction

Certain conditions causing swelling of the larynx can threaten the airway
Patient with a compromised upper airway will present with stridor, raised respiratory rate, distress, hypoxia +/- cyanosis